FIELD OF THE INVENTION:
The invention related to isolated peptides including a binding domain of the viral phosphoprotein (P) subunit to the viral RNA free nucleoprotein (N0
) which has the property to inhibit the replication of viruses from the subfamily Paramyxovirinae
(like Henipavirus, Rubulavirus or Morbillivirus). These isolated peptides may be used for the prevention or the treatment of Paramyxovirinae
BACKGROUND OF THE INVENTION:
are a large family of non-segmented negative-strand RNA viruses (NNV) associated with human respiratory illnesses (e.g. respiratory syncytial virus (RSV), human parainfluenza viruses) and with common childhood diseases such as measles and mumps. Owing to phylogenetic relationships, Paramyxoviridae
are divided in two subfamilies, the Paramyxovirinae
and the Pneumovirinae,
and are classified in the order Mononegavirales
with the families Rhabdoviridae, Bornaviridae
Nipah virus (NiV) is emblematic of emerging viruses; spilling over from its natural bat hosts in South East Asia, this virus causes outbreaks of respiratory and encephalic diseases in various mammals including humans1
. Its mortality rate that can exceed 70% in humans, its potential for human-to-human transmission and the absence of vaccine or specific antiviral treatment classify NiV among biosafety level-4 (BSL-4) pathogens.
The genomic RNA of NiV, like that of all NNV, is condensed by a homopolymer of nucleoprotein (N), forming long helical nucleocapsids (NCs). These ribonucleoprotein complexes are the biologically active templates used for RNA synthesis by the viral RNA-dependent RNA polymerase2,3
, and thus the replication of these viruses requires the continuous supply of unassembled N molecules to encapsidate the positive-sense and negative-sense progeny RNA molecules4
Consistent with the ability of the NNV NCs to protect genomic RNA against nucleases, the N proteins comprise two globular domains, N-terminal (NNTD
) and C-terminal (NCTD
) that completely enwrap the RNA molecule5-8
(Fig. 1a). The N homopolymer is stabilized by lateral contacts and by the exchange of N-terminal (NTARM
) and C-terminal subdomains (CTARM
) between adjacent protomers5-8
. The N of Paramyxovirinae
has an additional long disordered C-terminal tail (NTAIL
) that extends outside the NC and binds the C-terminal domain of P (PXD
. The tight packaging of the RNA raises the hypothesis that N must open and close to accommodate RNA inside the binding groove upon the NC assembly process and to transiently release the RNA template upon passage of the RNA polymerase, but until now, there is no evidence of a conversion between open and closed N forms.
In the absence of other viral proteins, N has a strong tendency to polymerize and assemble on cellular RNAs. In Paramyxoviridae,
but also in Rhabdoviridae
and perhaps in all NNVs, a viral protein acts as a specific chaperone of nascent N and keeps it in an assembly-competent form (N0
), by preventing both its polymerization and its interaction with cellular RNAs9,14
P proteins are modular multifunctional proteins, which comprise a long intrinsically disordered N-terminal region (PNTR) and a C-terminal region (PCTR) with a multimerization domain (PMD) connected by a flexible linker to an NC binding domain (PXD)11,15,16 (Fig. 1a) and are therefore highly flexible in solution 17. In both families, a short N-terminal region of P is sufficient to fulfill both chaperone roles9,18
. Here inventors study the soluble NiV N0
-P core complex to understand the mechanism of NC assembly.
When expressed in human cells, this P N0
-binding domain, comprising the first 40 aa of NiV P, is able to inhibit the replication of Nipah virus. Structure-based mutagenesis validates the N0
-P complex as the target for the inhibitory activity of the P peptide and for drug development against highly pathogenic members of the subfamily Paramyxovirinae
including NiV. Sequence conservation in the binding interface between N and P among various members of the Paramyxovirinae
subfamily raises the possibility of developing a broad spectrum drug against several viruses.
The polypeptide sequence of viral proteins, or nucleic acids encoding a phosphoprotein-derived polypeptide, such as the phosphoprotein of measles, have been reported in the Art, and in referenced databases such as the UniProtKB database (E7DWI2).
reports polypeptides which may bind to the nucleoprotein.
There remains a need for inhibiting the viral replication of Paramyxovirinae.
There also remains a need for treating or preventing a Paramyxovirinae infection.
The invention provides an isolated peptide of at most 100 amino-acid, which has the capacity of inhibiting the viral replication of Paramvxovirinae, comprising an amino acid sequence of formula (I):
Valine-Xaa1-Xaa2-Glycine-Leucine-Xaa3-Xaa4-Xaa5-Xaa6-Xaa7-Xaa8, wherein :
Xaa1 is glutamine (Q), serine (S) or asparagine (N), lysine (K), or an equivalent polar amino acid;
Xaa2 is glutamic acid (E), aspartic acid (D), asparagine (N), lysine (K), or an equivalent negatively charged (or acid) amino acid;
Xaa3 is glutamic acid (E), aspartic acid (D), lysine (K), glutamine (Q), serine (S) or asparagine (N);
Xaa4 is cysteine (C), isoleucine (I);
Xaa5 is isoleucine (I), leucine (L) or valine (V) or an equivalent apolar aliphatic amino acid;
Xaa6 is glutamine (Q), lysine (K), arginine (R) or aspartic acid (D);
Xaa7 is alanine (A), or phenylalanine (F) or an equivalent apolar amino acid;
Xaa8 is isoleucine (I), leucine (L) or valine (V) or an equivalent apolar aliphatic amino acid.
In preferred embodiments, Xaa5 is isoleucine (I), and Xaa8 is isoleucine (I). In preferred embodiments, Xaa1 is asparagine (N) or glutamine (Q), Xaa2 is aspartic acid (D) or glutamic acid (E), Xaa3 is asparagine (N) or glutamic acid (E), Xaa4 is isoleucine (I) or cysteine (C), Xaa5 is isoleucine (I), Xaa6 is aspartic acid (D) or glutamine (Q), Xaa7 is phenylalanine (F) or alanine (A), and Xaa8 is isoleucine (I).
The invention also provides an isolated peptide of at most 100 amino-acid, which has the capacity of inhibiting the viral replication of Paramyxovirinae, comprising the amino acid sequence of formula (II):
Xaa1- Xaa2 Xaa3-Xaa4- Xaa5-Xaa6-Xaa7-Xaa8 are defined above
Yaa1 is aspartic acid (D), glutamic acid (E), or an equivalent acidic amino acid,.
Yaa2 is glutamine (Q) or lysine (K),
Yaa3 is alanine (A), leucine (L) or tyrosine (Y),
Yaa4 is glutamic acid (E), tyrosine (Y) or arginine (R),
Yaa5 is asparagine (N), histidine (H) or leucine (L),
Yaa6 is glutamine (Q), lysine (K), or arginine (R),
Yaa7 is lysine (K), alanine (A) or glutamic acid (E),
Yaa8 is asparagines (N), glutamic acid (E) or serine (S).
In preferred embodiments, Yaa1 is aspartic acid (D). In preferred embodiments, Yaa1 is aspartic acid (D), Yaa2 is lysine (K) or glutamine (Q), Yaa3 is leucine (L) or alanine (A), Yaa4 is glutamic acid (E), Yaa5 is leucine (L) or asparagine (N), Yaa6 is glutamine (Q), Yaa7 is lysine (K), and Yaa8 is asparagines (N).
In a preferred embodiment, the isolated peptide comprises or consists of the sequence SEQ ID NO: 3) or the amino acid sequence ranging from the valine residue at position 7 to the isoleucine residue at position 17 in SEQ ID N0:1 P7-17 of SEQ ID N0:1
In some embodiments, the isolated peptide is linked with at least one cell penetrating peptide,
Also encompasses are polynucleotides comprising or consisting of a nucleotidic sequence encoding a peptide according to the invention,
The invention further relates to methods for preparing or generating the peptides of the invention.
The invention further relates to a pharmaceutical composition comprising a peptide of the invention, together with a pharmaceutically acceptable carrier, and to the use of the peptides or the pharmaceutical composition according to the invention for treating or preventing Paramyxovirinae infection.
The invention further relates to an isolated peptide of at most 100 amino-acid, for use in a method for preventing and/or treating a Paramyxovirinae infection ; the said isolated peptide comprising an amino acid sequence of formula (I).
The inventors have identified sequence from the viral Phophoprotein P subunit in the N-terminal region which interacts with its partner the unassembled RNA-free viral nucleoprotein (N0
) (SEQ ID NO.1: MDKLELVNDGLNIIDFIQKNQKEIQKTYGRSSIQQPSIKD, positions 1-40 of viral Nipah Phosphoprotein P sequence deposited in Swiss-Prot database under accession number Q9IK91). This N0
binding domain corresponds to amino acid positions 1-40. This P N0
-binding domain, when expressed in cells, is able to inhibit the replication of Nipah virus. The inventors have identified the molecular protein partner of this peptide (the viral unassembled nucleoprotein N0
) and solve the crystal structure of the complex. The inventors have obtained evidence that the peptide competes with the native phosphoprotein P for binding to this protein partner. The interface between the phosphoprotein P and the nucleoprotein N0
is conserved among several members of the viral subfamily Paramyxovirinae
(including measles and mumps viruses).
The inventors have also generated shorter isolated peptides from this 1-40 Nipah phosphoprotein P subunit with different lengths: between 11 and 37 amino acids (P6-40, P11-40; P1-20; P20-35 and P7-17) which have the ability to inhibit the phosphoprotein P / nucleoprotein N0
interaction and consecutively to inhibit viral replication.
The inventors have further generated isolated peptides from CDV phosphoprotein P subunit, consisting of residues 1 to 40 (SEQ ID NO.2 : MAEEQAYHVSKGLECLKALRENPPDIEEIQEVSSLRDQTC, positions 1-40 of viral CDV phosphoprotein P sequence (NCBI Reference strain NC_001921.1)) and shorter peptides P1-22, P9-19, which exhibits a similar activity as the 1-40 Nipah virus phosphoprotein P subunit.
The inventors have further generated, based on this conserved sequence of the phosphoprotein P subunit among the members of the viral subfamily Paramyxovirinae,
a consensus peptide that includes the conserved (in bold) and the best residues at the other positions (SEQ ID NO.3 : DQAENVQEGLECIQAIQKN).
The inventors have further generated isolated peptides from Measles virus phosphoprotein P subunit, consisting of residues 1 to 40 (SEQ ID NO.4 : MAEEQARHVKNGLECIRALKAEPIGSLAIEEAMAAWSEIS, positions 1-40 of viral MeV phosphoprotein P sequence deposited in Swiss-Prot database under accession number (Q76VZ7_MEASE) and shorter peptide P9-19, which exhibits a similar activity as the 1-40 Nipah virus phosphoprotein P subunit.
The inventors have thus found a new targeted therapy for treating viral infection by members of the Paramyxovirinae
subfamily with no available targeted therapy. Said invention is particularly advantageous for treating infections by Rubulaviruses, Henipaviruses, Morbilliviruses.
Throughout the specification, several terms are employed and are defined in the following paragraphs.
As used herein, the term "Paramyxovirinae"
denotes a subfamily of the Paramyxoviridae.
Members of this subfamily are enveloped viruses with a non-segmented, negative, single-stranded RNA genome encapsidated by a virally encoded nucleoprotein (N) within a helical nucleocapsid. Transcription and replication of this (N:RNA) template are carried out by a viral RNA-dependent RNA polymerase complex, made of the phosphoprotein (P) and the large protein (L) (reviewed by Lamb & Kolakofsky, 2001). Association of P with the soluble, monomeric form of N (N0
) prevents its illegitimate self-assembly onto cellular RNA. "Paramyxovirinae"
include major human pathogens such as parainfluenza virus and measles virus (MV),
The different "Paramyxovirinae"
genera are :
Genus Aquaparamyxovirus (type species Atlantic salmon paramyxovirus: others include Pacific salmon paramyxovirus)
Genus Avulavirus (type species Newcastle disease virus)
Genus Ferlavirus (Fer-de-Lance virus)
Genus Henipavirus (type species Hendravirus; others include Nipah virus)
Genus Morbillivirus (type species Measles virus; others include Rinderpest virus, Canine distemper virus, phocine distemper virus, Ovine rinderpest)
Genus Respirovirus (type species Sendai virus; others include Human parainfluenza viruses 1 and 3, as well some of the viruses of the common cold)
Genus Rubulavirus (type species Mumps virus; others include Achimota virus 1 and 2, Human parainfluenza viruses 2 and 4, Simian parainfluenza virus 5, Menangle virus, Tioman virus, Tuhokovirus 1, 2 and 3)
Genus TPMV-like viruses (type species Tupaia paramyxovirus: other species Mossman virus, Nariva virus and Salem virus)
As used herein, the term "amino acid" refers to natural or unnatural amino acids in their D and L stereoisomers for chiral amino acids. It is understood to refer to both amino acids and the corresponding amino acid residues, such as are present, for example, in peptidyl structure. Natural and unnatural amino acids are well known in the art. Common natural amino acids include, without limitation, alanine (Ala), arginine (Arg), asparagine (Asn), aspartic acid (Asp), cysteine (Cys), glutamine (Gln), glutamic acid (Glu), glycine (Gly), histidine (His), isoleucine (Ile), leucine (Leu), Lysine (Lys), methionine (Met), phenylalanine (Phe), proline (Pro), serine (Ser), threonine (Thr), tryptophan (Trp), tyrosine (Tyr), and valine (Val). Uncommon and unnatural amino acids include, without limitation, allyl glycine (AllylGly), norleucine, norvaline, biphenylalanine (Bip), citrulline (Cit), 4-guanidinophenylalanine (Phe(Gu)), homoarginine (hArg), homolysine (hLys), 2-naphtylalanine (2-Nal), ornithine (Orn) and pentafluorophenylalanine.
Amino acids are typically classified in one or more categories, including polar, hydrophobic, acidic, basic and aromatic, according to their side chains. Examples of polar amino acids include those having side chain functional groups such as hydroxyl, sulfhydryl, and amide, as well as the acidic and basic amino acids. Polar amino acids include, without limitation, asparagine, cysteine, glutamine, histidine, selenocysteine, serine, threonine, tryptophan and tyrosine. Examples of hydrophobic or non-polar amino acids include those residues having nonpolar aliphatic side chains, such as, without limitation, leucine, isoleucine, valine, glycine, alanine, proline, methionine and phenylalanine. Examples of basic amino acid residues include those having a basic side chain, such as an amino or guanidino group. Basic amino acid residues include, without limitation, arginine, homolysine and lysine. Examples of acidic amino acid residues include those having an acidic side chain functional group, such as a carboxy group. Acidic amino acid residues include, without limitation aspartic acid and glutamic acid. Aromatic amino acids include those having an aromatic side chain group. Examples of aromatic amino acids include, without limitation, biphenylalanine, histidine, 2-napthylalananine, pentafluorophenylalanine, phenylalanine, tryptophan and tyrosine. It is noted that some amino acids are classified in more than one group, for example, histidine, tryptophan and tyrosine are classified as both polar and aromatic amino acids. Amino acids may further be classified as non-charged, or charged (positively or negatively) amino acids. Examples of positively charged amino acids include without limitation lysine, arginine and histidine. Examples of negatively charged amino acids include without limitation glutamic acid and aspartic acid. Additional amino acids that are classified in each of the above groups are known to those of ordinary skill in the art.
"Equivalent amino acid" means an amino acid which may be substituted for another amino acid in the peptide compounds according to the invention without any appreciable loss of function. Equivalent amino acids will be recognized by those of ordinary skill in the art. Substitution of like amino acids is made on the basis of relative similarity of side chain substituents, for example regarding size, charge, hydrophilicity and hydrophobicity as described herein. The phrase "or an equivalent amino acid thereof" when used following a list of individual amino acids means an equivalent of one or more of the individual amino acids included in the list.
The N- and C-termini of the peptides described herein may be protected against proteolysis. For instance, the N-terminus may be in the form of an acetyl group, and/or the C-terminus may be in the form of an amide group. Internal modifications of the peptides to be resistant to proteolysis are also envisioned, e.g. wherein at least a -CONH peptide bond is modified and replaced by a (CH2NH) reduced bond, a (NHCO) retro-inverso bond, a (CH2-O) methylene-oxy bond, a (CH2-S) thiomethylene bond, a (CH2CH2) carba bond, a (CO-CH2) cetomethylene bond, a (CHOH-CH2) hydroxyethylene bond), a (N-N) bound, a E-alcene bond or also a -CH=CH-bond. The peptides described herein may also be protected against proteolysis by the technique of stapled peptides as described by Walensky et al. Science. 2004, 305, 1466-70
In another aspect of the invention, peptides are covalently bound to a polyethylene glycol (PEG) molecule by their C terminus or a lysine residue, notably a PEG of 1500 or 4000 MW, for a decrease in urinary clearance and in therapeutic doses used and for an increase of the half-life in blood plasma. In yet another embodiment, peptide half-life is increased by including the peptide in a biodegradable and biocompatible polymer material for drug delivery system forming microspheres. Polymers and copolymers are, for instance, poly (D, L-lactide-co-glycol ide) (PLGA) (as illustrated in US2007/0184015
, SoonKap Hahn et al).
The terms "cell penetrating peptide" or "CPP" are used interchangeably and refer to cationic cell penetrating peptides, also called transport peptides, carrier peptides, or peptide transduction domains. The CPP, as shown herein, have the capability of inducing cell penetration of a peptide fused to the CPP within 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of cells of a given cell culture population, including all integers in between, and allow macromolecular translocation within multiple tissues in vivo upon systemic administration. A cell-penetrating peptide may also refer to a peptide which, when brought into contact with a cell under appropriate conditions, passes from the external environment in the intracellular environment, including the cytoplasm, organelles such as mitochondria, or the nucleus of the cell, in conditions significantly greater than passive diffusion. Such penetrating peptides may be those described in Fonseca S.B. et al., Advanced Drug Delivery Reviews, 2009, 61: 953-964
, Johansson et al., Methods in Molecular Biology, 2011, Vol. 683, Chapter 17
, Bechara and Sagan, (2013) FEBS letters 587, 1693-1702
.; Jones and Sayers (2012), Journal of controlled release : official journal of the Controlled Release Society 161, 582-591
; Khafagy el and Morishita, (2012) Advanced drug delivery reviews 64, 531-539
; Malhi and Murthy, (2012) Expert opinion on drug delivery 9, 909-935
, in WO2004/011595
and in WO2003/011898
. All that CPP are incorporated by reference.
By "stringent conditions", it is meant conditions of temperature and ionic strength allowing specific hybridization between two complementary nucleic acid fragments and limiting non-specific binding (Sambrook et al. Molecular Cloning, Second Edition (1989), 9.47-9.62). The temperature conditions are generally comprised between (Tm - 5°C) and (Tm - 10°C), Tm being the theoretical fusion temperature, which is defined as the temperature at which 50 % of the paired strands separate. For sequences comprising more than 30 bases, Tm is defined by the formula: Tm = 81.5 + 0.41 (% G+C) + 16.6Log (cations concentration) - 0.63 (% formamide) - (600/bases number). For sequences comprising less than 30 bases, Tm is defined by the formula: Tm = 4 (G+C) + 2 (A+T).
As used herein, the term "pharmaceutically acceptable" and grammatical variations thereof, as they refer to compositions, carriers, diluents and reagents, are used interchangeably and represent that the materials are capable of administration to or upon a mammal without the production of undesirable physiological effects such as nausea, dizziness, gastric upset and the like.
The term "patient" or "subject" refers to a human or non human mammal, preferably a mouse, cat, dog, monkey, horse, cattle (i.e. cow, sheep, goat, buffalo), including male, female, adults and children.
As used herein, the term "treatment" or "therapy" includes curative and/or prophylactic treatment. More particularly, curative treatment refers to any of the alleviation, amelioration and/or elimination, reduction and/or stabilization (e.g., failure to progress to more advanced stages) of a symptom, as well as delay in progression of a symptom of a particular disorder. Prophylactic treatment refers to any of: halting the onset, reducing the risk of development, reducing the incidence, delaying the onset, reducing the development, as well as increasing the time to onset of symptoms of a particular disorder.
The present description reports novel isolated peptides derived from N terminal phosphoprotein P of Paramyxovirinae virus, which have capacity to inhibit the phosphoprotein P / nucleoprotein N0
interaction of Paramyxovirinae virus; and/or to inhibit the viral replication of Paramyxovirinae.
In one aspect, the invention provides an isolated peptide of at most 100 amino-acid, which has the capacity of inhibiting the viral replication of Paramyxovirinae,, comprising an amino acid sequence of formula (I):
Xaa1 is glutamine (Q), serine (S), asparagine (N), lysine (K) or an equivalent polar amino acid.
Xaa2 is glutamic acid (E), aspartic acid (D), asparagine (N), lysine (K), or an equivalent negatively charged (or acid) amino acid,
Yaa1 is aspartic acid (D), glutamic acid (E) or an equivalent acidic amino acid,
Yaa2 is glutamine (Q) or lysine (K),
Yaa3 is alanine (A), leucine (L) or tyrosine (Y),
Yaa4 is glutamic acid (E), or tyrosine (Y) or arginine (R),
Yaa5 is asparagine (N), histidine (H) or leucine (L),
Yaa6 is glutamine (Q), lysine (K) or arginine (R),
Yaa7 is lysine (K), alanine (A) or glutamic acid (E),
Yaa8 is asparagines (N), glutamic acid (E) or serine (S).
In preferred embodiments, Yaa1 is aspartic acid (D). In preferred embodiments, Yaa1 is aspartic acid (D), Yaa2 is lysine (K) or glutamine (Q), Yaa3 is leucine (L) or alanine (A), Yaa4 is glutamic acid (E), Yaa5 is leucine (L) or asparagine (N), Yaa6 is glutamine (Q), Yaa7 is lysine (K), and Yaa8 is asparagine (N).
In a preferred embodiment, the peptide comprises or consists of the sequence SEQ ID NO: 3 DQAENVQEGLECIQAIQKN) or the amino acid sequence ranging from the valine residue at position 7 to the isoleucine residue at position 17 in SEQ ID NO:1 P7-17 of SEQ ID N01.
Preferably, an isolated peptide according to the invention has the capacity (i) to inhibit the phosphoprotein P / nucleoprotein N0
interaction of Paramyxovirinae
virus; and/or (ii) to inhibit the viral replication of Paramyxovirinae.
The skilled in the art can easily determine whether isolated peptide is biologically active. For example, the capacity to inhibit the phosphosprotein P / nucleoprotein N° interaction can for example be determined by assessing N0
-P fragment complex formation leading to the solubilization of N through inhibition of oligomerisation as shown by changes in cellular localisation and absence of punctuate appearance of N as evidenced by immunofluorescence studies (e.g. as described in Example 2 and Fig. 1d). The capacity of associating with nucleoprotein N0
can be determined by analyzing co-localization with nucleoprotein N0
in immunofluorescence studies and/or assessing nucleoprotein N0
binding in cell extract, e.g. using the co-sedimentation protocol described in Rodrigues-Ferreira et al. (2009, PLoS One. 4(10):e7239 2009
The capacity to inhibit viral replication can for example be determined measuring viral growth titers for virus cultivated in the presence of inhibitors and/or by assessing abolition of syncytia formation through experiments (e.g. as described in Example + Figures 3b,c). The syncytia formation, which is a hallmark of Paramyxoviruses infection, can be determined using the luciferase-based syncytium quantitative assay described in Barbeau B et al. (J Virol. 1998 Sep;72(9):7125-36
As used herein, a "biologically active" fragment refers to a fragment exhibiting at least one, preferably all, of the biological activities of a peptide of SEQ ID NO: 1, provided the biologically active fragment retains the capacity of inhibiting viral replication. The biologically active fragment may for example be characterized in that it is capable of inhibiting the phophosprotein P / nucleoprotein N° interaction when assessed through co-localization experiments (see Example 2 and Fig. 1d) and/or inhibiting viral replication when assessed through measurement of viral replication titers and/or syncytia formation experiments and/or qPCR quantification of viral genomic RNA or mRNA (see Example and Figures 3b,c).
In particular embodiment, the invention provide an isolated peptide selected from the group consisting of :
- i) the amino acids sequence consisting of MDKLELVNDGLNIIDFIQKNQKEIQKTYGRSSIQQPSIKD (SEQ ID NO: 1);
- ii) an amino acid sequence ranging from the leucine residue at position 6 to the aspartic acid residue at position 40 in SEQ ID NO:1 P6-40 of SEQ ID N01;
- iii) an amino acid sequence ranging from the leucine residue at position 11 to the aspartic acid residue at position 40 in SEQ ID NO:1 P11-40 of SEQ ID N01;
- iv) an amino acid sequence ranging from the methionine residue at position 1 to the asparagine residue at position 20 in SEQ ID NO:1 P1-20 of SEQ ID N01;
- v) an amino acid sequence ranging from asparagine residue at position 20 to the glutamine residue at position 35 in SEQ ID NO:1 P20-35 of SEQ ID N01;
- vi) the amino acids sequence consisting of MAEEQAYHVSKGLECLKALRENPPDIEEIQEVSSLRDQTC (SEQ ID NO: 2);
- vii) an amino acid sequence ranging from the methionine residue at position 1 to the asparagine residue at position 22 in SEQ ID NO:2 P1-22 of SEQ ID N02;
- viii) the amino acids sequence consisting of DQAENVQEGLECIQAIQKN (SEQ ID NO: 3)
- ix) the amino acids sequence consisting of MAEEQARHVKNGLECIRALKAEPIGSLAIEEAMAAWSEIS (SEQ ID NO: 4) P40 MeV
- x) an amino acid sequence ranging from the valine residue at position 9 to the leucine residue at position 19 in SEQ ID NO:4 P9-19 of SEQ ID N04.
- xi) an amino acid sequence substantially homologous to the sequence of (i) to (x) preferably an amino acid a sequence at least 80% identical to the sequence of (i) to (x).
A peptide "substantially homologous" to a reference peptide may derive from the reference sequence by one or more conservative substitutions. Preferably, these homologous peptides do not include two cysteine residues, so that cyclization is prevented. Two amino acid sequences are "substantially homologous" or "substantially similar" when one or more amino acid residue are replaced by a biologically similar residue or when greater than 80 % of the amino acids are identical, or greater than about 90 %, preferably greater than about 95%, are similar (functionally identical). Preferably, the similar, identical or homologous sequences are identified by alignment using, for example, the GCG (Genetics Computer Group, Program Manual for the GCG Package, Version 7, Madison, Wisconsin) pileup program, or any of the programs known in the art (BLAST, FASTA, etc.). The percentage of identity may be calculated by performing a pairwise global alignment based on the Needleman-Wunsch alignment algorithm to find the optimum alignment (including gaps) of two sequences along their entire length, for instance using Needle, and using the BLOSUM62 matrix with a gap opening penalty of 10 and a gap extension penalty of 0.5.
The term "conservative substitution" as used herein denotes the replacement of an amino acid residue by another, without altering the overall conformation and function of the peptide, including, but not limited to, replacement of an amino acid with one having similar properties (such as, for example, polarity, hydrogen bonding potential, acidic, basic, shape, hydrophobic, aromatic, and the like). Amino acids with similar properties are well known in the art. For example, arginine, histidine and lysine are hydrophilic-basic amino acids and may be interchangeable. Similarly, isoleucine, a hydrophobic amino acid, may be replaced with leucine, methionine or valine. Neutral hydrophilic amino acids, which can be substituted for one another, include asparagine, glutamine, serine and threonine.
By "substituted" or "modified" the present invention includes those amino acids that have been altered or modified from naturally occurring amino acids.
As such, it should be understood that in the context of the present invention, a conservative substitution is recognized in the art as a substitution of one amino acid for another amino acid that has similar properties.
According to the invention a first amino acid sequence having at least 80% of identity with a second amino acid sequence means that the first sequence has 80; 81; 82; 83; 84; 85; 86; 87; 88; 89; 90; 91; 92; 93; 94; 95; 96; 97; 98; or 99% of identity with the second amino acid sequence. Amino acid sequence identity is preferably determined using a suitable sequence alignment algorithm and default parameters, such as BLAST P (Karlin and Altschul, 1990).
In some embodiments, the isolated peptide of the invention comprises at most 100 aminoacid (and at least 9). In some embodiments, the polypeptide of the invention comprises 100; 99; 98; 97; 96; 95; 94; 93; 92; 91; 90; 89; 88; 87; 86; 85; 84; 83; 82; 81; 80; 79; 78; 77; 76; 75; 74; 73; 72; 71; 70; 69; 68; 67; 66; 65; 64; 63; 62; 61; 60; 59; 58; 57; 56; 55; 54; 53; 52; 51; 50; 49; 48; 47; 46; 45; 44; 43; 42; 41; 40; 39; 38; 37; 36; 35; 34; 33; 32; 31; 30; 29; 28; 27; 26; 25; 24; 23; 22; 21; 20; 19; 18; 17; 16; 15; 14; 13; 12; 11; 10 or 9 amino acids. In some embodiments, the polypeptide of the invention comprises less than 50 amino acids In some embodiments, the polypeptide of the invention comprises less than 30 amino acids. In some embodiments, the polypeptide of the invention comprises less than 25 amino acids. In some embodiments, the polypeptide of the invention comprises less than 20 amino acids. In some embodiments, the polypeptide of the invention comprises less than 15 amino acids.
In some embodiments, the isolated phosphoprotein P peptide is linked with at least one cell penetrating peptide (CPP), forming a chimeric peptide.
In a preferred embodiment, the cell penetrating peptide comprises or consists of:
Tat peptide, polyarginines peptide, HA2-R9 peptide, Penetratin peptide, Transportan peptide, Vectocell® peptide, maurocalcine peptide, decalysine peptide, HIV-Tat derived PTD4 peptide, Hepatitis B virus Translocation Motif (PTM) peptide, mPrP1-28 peptide, POD, pVEC, EB1, Rath, CADY, Histatin 5, Antp peptide, Cyt86-101 peptide, DPT peptide.
By "Tat peptide", it is meant a peptide having the sequence RKKRRQRRR (SEQ ID NO: 5 Tat peptide 2) or YGRKKRRQRRR, (SEQ ID NO: 6).
By "polyarginines peptide", it is meant a peptide consisting of at least 9 arginines. Preferably, a polyarginine peptide is a peptide having the sequence R9
(SEQ ID NO: 7) or R11
(SEQ ID NO: 8).
peptide", it is meant a peptide having the sequence GLFEAIEGFIENGWEGMIDGWYG-R9
(SEQ ID NO: 9).
By "Penetratin peptide", it is meant a peptide having the sequence RQIKIWFQNRRMKWKK (SEQ ID NO: 10).
By "Transportan peptide", it is meant a peptide having the sequence GWTLNSAGYLLGKINLKALAALAKKIL (SEQ ID NO: 11).
By "Vectocell® peptide", it is meant a peptide originating from human heparin binding proteins and/or anti-DNA antibodies.
By "Maurocalcine peptide", it is meant a peptide having the sequence GDCLPHLKLCKENKDCCSKKCKRRGTNIEKRCR (SEQ ID NO: 12).
By "decalysine peptide", it is meant a peptide having the sequence KKKKKKKKKK (K10
) (SEQ ID NO: 13).
By "HIV-Tat derived PTD4 peptide", it is meant a peptide having the sequence YARAAARQARA (SEQ ID NO: 14).
By "Hepatitis B virus Translocation Motif (PTM) peptide", it is meant a peptide having the sequence PLSSIFSRIGDP (SEQ ID NO: 15).
By "mPrP1-28 peptide", it is meant a peptide having the sequence MANLGYWLLALFVTMWTDVGLCKKRPKP (SEQ ID NO: 16).
By "POD peptide", it is meant a peptide having the sequence GGG(ARKKAAKA)4
(SEQ ID NO: 17).
By "pVEC peptide", it is meant a peptide having the sequence LLIILRRRRIRKQAHAHSK (SEQ ID NO: 18).
By "EB1 peptide", it is meant a peptide having the sequence LIRLWSHLIHIWFQNRRLKWKKK (SEQ ID NO: 19).
By "Rath peptide", it is meant a peptide having the sequence TPWWRLWTKWHHKRRDLPRKPE (SEQ ID NO: 20).
By "CADY peptide", it is meant a peptide having the sequence GLWRALWRLLRSLWRLLWRA (SEQ ID NO: 21).
By "Histatin 5 peptide", it is meant a peptide having the sequence DSHAKRHHGYKRKFHEKHHSHRGY (SEQ ID NO: 22).
By "Antp peptide", it is meant a peptide having the sequence RQIKIWFQNRRMKWKK (SEQ ID NO: 23).
By "Cyt86-101 peptide", it is meant a peptide having the sequence KKKEERADLIAYLKKA (SEQ ID NO: 24).
By "DPT peptide", it is meant a peptide having the sequence VKKKKIKREIKI (SEQ ID NO: 25)
In another preferred embodiment, the phosphoprotein P peptide is linked to two, three or more penetrating peptides.
As isolated peptide the chimeric peptide according to the invention has the capacity to inhibit the phosphoprotein P / nucleoprotein N0
interaction of Paramyxovirinae virus; and/or to inhibit the viral replication of Paramyxovirinae.
The invention also relates to a polynucleotide comprising or consisting of a nucleotidic sequence encoding an isolated peptide according to the invention.
In an embodiment, the polynucleotide comprises or consists of a nucleotidic sequence selected from:
- SEQ ID NO : 26 (5'-ATGGATAAATTGGAACTAGTCAATGATGGCCTCAATATTATTGACTTTATTCAGA AGAACCAAAAAGAAATACAGAAGACATACGGACGATCAAGTATTCAACAACCCA GCATCAAAGAT -3') ; P40 Nipah
- SEQ ID NO : 27 (5'-ATGGCAGAGGAACAGGCCTACCATGTCAGCAAAGGGCTGGAATGCCTCAAAGCC CTCAGAGAGAATCCTCCTGACATTGAGGAGATTCAAGAGGTCAGCAGCCTCAGA GACCAAACCTGC -3') ;P40 CDV
- SEQ ID NO : 28 (5'-ATGGCAGAAGAGCAGGCACGCCATGTCAAAAACGGACTGGAATGCATCCGGGCT CTCAAGGCCGAGCCCATCGGCTCACTGGCCATCGAGGAAGCTATGGCAGCATGGT CAGAAATATCA -3') ; P40 MeV
respectively coding the peptide of sequences SEQ ID NO: 1, 2, 4.
The invention also relates to polynucleotides with nucleotidic sequences complementary to one of the sequence as described above and to sequences hybridizing to said polynucleotides under stringent conditions.
The invention further relates to a genetic construct consisting of or comprising a polynucleotide as defined herein, and regulatory sequences (such as a suitable promoter(s), enhancer(s), terminator(s), etc.) allowing the expression (e.g. transcription and translation) of a peptide according to the invention in a host cell.
The genetic constructs of the invention may be DNA or RNA, and are preferably double-stranded DNA. The genetic constructs of the invention may also be in a form suitable for transformation of the intended host cell or host organism, in a form suitable for integration into the genomic DNA of the intended host cell or in a form suitable for independent replication, maintenance and/or inheritance in the intended host organism. For instance, the genetic constructs of the invention may be in the form of a vector, such as for example a plasmid, cosmid, YAC, a viral vector or transposon. In particular, the vector may be an expression vector, i.e. a vector that can provide for expression in vitro and/or in vivo (e.g. in a suitable host cell, host organism and/or expression system).
In a preferred but non-limiting aspect, a genetic construct of the invention comprises i) at least one nucleic acid of the invention; operably connected to ii) one or more regulatory elements, such as a promoter and optionally a suitable terminator; and optionally also iii) one or more further elements of genetic constructs known per se; in which the terms "regulatory element", "promoter", "terminator" and "operably connected" have their usual meaning in the art (as further described herein); and in which said "further elements" present in the genetic constructs may for example be 3'- or 5'-UTR sequences, leader sequences, selection markers, expression markers/reporter genes, and/or elements that may facilitate or increase (the efficiency of) transformation or integration. These and other suitable elements for such genetic constructs will be clear to the skilled person, and may for instance depend upon the type of construct used, the intended host cell or host organism; the manner in which the nucleotide sequences of the invention of interest are to be expressed (e.g. via constitutive, transient or inducible expression); and/or the transformation technique to be used. For example, regulatory requences, promoters and terminators known per se for the expression and production of antibodies and antibody fragments (including but not limited to (single) domain antibodies and ScFv fragments) may be used in an essentially analogous manner.
Preferably, in the genetic constructs of the invention, said at least one nucleic acid of the invention and said regulatory elements, and optionally said one or more further elements, are "operably linked" to each other, by which is generally meant that they are in a functional relationship with each other. For instance, a promoter is considered "operably linked" to a coding sequence if said promoter is able to initiate or otherwise control/regulate the transcription and/or the expression of a coding sequence (in which said coding sequence should be understood as being "under the control of" said promotor). Generally, when two nucleotide sequences are operably linked, they will be in the same orientation and usually also in the same reading frame. They will usually also be essentially contiguous, although this may also not be required.
Preferably, the regulatory and further elements of the genetic constructs of the invention are such that they are capable of providing their intended biological function in the intended host cell or host organism.
For instance, a promoter, enhancer or terminator should be "operable" in the intended host cell or host organism, by which is meant that (for example) said promoter should be capable of initiating or otherwise controlling/regulating the transcription and/or the expression of a nucleotide sequence as defined herein, e.g. a coding sequence, to which it is operably linked.
Some particularly preferred promoters include, but are not limited to, promoters known per se for the expression in the host cells mentioned herein; and in particular promoters for the expression in the bacterial cells.
A selection marker should be such that it allows, i.e. under appropriate selection conditions, host cells and/or host organisms that have been (successfully) transformed with the nucleotide sequence of the invention to be distinguished from host cells/organisms that have not been (successfully) transformed. Some preferred, but non-limiting examples of such markers are genes that provide resistance against antibiotics (such as kanamycin or ampicillin), genes that provide for temperature resistance, or genes that allow the host cell or host organism to be maintained in the absence of certain factors, compounds and/or (food) components in the medium that are essential for survival of the non-transformed cells or organisms.
A leader sequence should be such that in the intended host cell or host organism--it allows for the desired post-translational modifications and/or such that it directs the transcribed mRNA to a desired part or organelle of a cell. A leader sequence may also allow for secretion of the expression product from said cell. As such, the leader sequence may be any pro-, pre-, or prepro-sequence operable in the host cell or host organism.
An expression marker or reporter gene should be such that--in the host cell or host organism--it allows for detection of the expression of a gene or nucleotide sequence present on the genetic construct. An expression marker may optionally also allow for the localisation of the expressed product, e.g. in a specific part or organelle of a cell and/or in (a) specific cell(s), tissue(s), organ(s) or part(s) of a multicellular organism. Such reporter genes may also be expressed as a protein fusion with the amino acid sequence of the invention. Some preferred, but non-limiting examples include fluorescent proteins such as GFP.
Some preferred, but non-limiting examples of suitable promoters, terminator and further elements include those that can be used for the expression in the host cells mentioned herein; and in particular those that are suitable for expression in bacterial cells, such as those mentioned herein. For some (further) non-limiting examples of the promoters, selection markers, leader sequences, expression markers and further elements that may be present/used in the genetic constructs of the invention, such as terminators, transcriptional and/or translational enhancers and/or integration factors, reference is made to the general handbooks such as Sambrook et al. Other examples will be clear to the skilled person.
The genetic constructs of the invention may generally be provided by suitably linking the nucleotide sequence(s) of the invention to the one or more further elements described above, for example using the techniques described in the general handbooks such as Sambrook et al.
Often, the genetic constructs of the invention will be obtained by inserting a nucleotide sequence of the invention in a suitable (expression) vector known per se.
The nucleic acids of the invention and/or the genetic constructs of the invention may be used to transform a host cell or host organism, i.e. for expression and/or production of the peptides of the invention.
Thus, in another aspect, the invention relates to a host or host cell that expresses (or that under suitable circumstances is capable of expressing) a peptide of the invention; and/or that contains a polynucleotide of the invention or genetic construct of the invention. Suitable hosts or host cells will be clear to the skilled person, and may for example be any suitable fungal, prokaryotic or eukaryotic cell or cell line or any suitable fungal, prokaryotic or eukaryotic organism, for example: a bacterial strain, including but not limited to gram-negative strains such as strains of Escherichia coli; of Proteus, for example of Proteus mirabilis; of Pseudomonas, for example of Pseudomonas fluorescens; and gram-positive strains such as strains of Bacillus, for example of Bacillus subtilis or of Bacillus brevis; of Streptomyces, for example of Streptomyces lividans; of Staphylococcus, for example of Staphylococcus carnosus; and of Lactococcus, for example of Lactococcus lactis; a fungal cell, including but not limited to cells from species of Trichoderma, for example from Trichoderma reesei; of Neurospora, for example from Neurospora crassa; of Sordaria, for example from Sordaria macrospore; of Aspergillus, for example from Aspergillus niger or from Aspergillus sojae; or from other filamentous fungi; a yeast cell, including but not limited to cells from species of Saccharomyces, for example of Saccharomyces cerevisiae; of Schizosaccharomyces, for example of Schizosaccharomyces pombe; of Pichia, for example of Pichia pastoris or of Pichia methanolica; of Hansenula, for example of Hansenula polymorpha; of Kluyveromyces, for example of Kluyveromyces lactis; of Arxula, for example of Arxula adeninivorans; of Yarrowia, for example of Yarrowia lipolytica; an amphibian cell or cell line, such as Xenopus oocytes; an insect-derived cell or cell line, such as cells/cell lines derived from lepidoptera, including but not limited to Spodoptera SF9 and Sf21 cells or cells/cell lines derived from Drosophila, such as Schneider and Kc cells; a plant or plant cell, for example in tobacco plants; and/or a mammalian cell or cell line, for example a cell or cell line derived from a human, a cell or a cell line from mammals including but not limited to CHO-cells, BHK-cells (for example BHK-21 cells) and human cells or cell lines such as HeLa, COS (for example COS-7) and PER.C6 cells.
Method of preparing peptides
The invention further relates to methods for preparing or generating the peptides of the invention.
The peptides of the invention may be produced by any well-known procedure in the art, including chemical synthesis technologies and recombinant technologies.
Examples of chemical synthesis technologies are solid phase synthesis and liquid phase synthesis. As a solid phase synthesis, for example, the amino acid corresponding to the C-terminus of the peptide to be synthesized is bound to a support which is insoluble in organic solvents, and by alternate repetition of reactions, one wherein amino acids with their amino groups and side chain functional groups protected with appropriate protective groups are condensed one by one in order from the C-terminus to the N- terminus, and one where the amino acids bound to the resin or the protective group of the amino groups of the peptides are released, the peptide chain is thus extended in this manner. Solid phase synthesis methods are largely classified by the tBoc method and the Fmoc method, depending on the type of protective group used. Typically used protective groups include tBoe (t-butoxycarbonyl), Cl-Z (2-chlorobenzyloxycarbonyl), Br-Z (2-bromobenzyloyycarbonyl), Bzl (benzyl), Fmoc (9-fluorenylmcthoxycarbonyl), Mbh (4, 4'-dimethoxydibenzhydryl), Mtr (4-methoxy-2, 3, 6-trimethylbenzenesulphonyl), Trt (trityl), Tos (tosyl), Z (benzyloxycarbonyl) and Clz-Bzl (2, 6-dichlorobenzyl) for the amino groups; NO2 (nitro) and Pmc (2,2, 5,7, 8-pentamethylchromane-6-sulphonyl) for the guanidino groups); and tBu (t-butyl) for the hydroxyl groups). After synthesis of the desired peptide, it is subjected to the de-protection reaction and cut out from the solid support. Such peptide cutting reaction may be carried with hydrogen fluoride or tri-fluoromethane sulfonic acid for the Boc method, and with TFA for the Fmoc method.
Alternatively, the peptide may be synthesized using recombinant techniques. In this case, a nucleic acid and/or a genetic construct according to the invention as described above is/are used.
The method of producing the peptide may optionally comprise the steps of purifying said peptide, chemically modifying said peptide, and/or formulating said peptide into a pharmaceutical composition.
The invention further relates to a pharmaceutical composition comprising a peptide of the invention, together with a pharmaceutically acceptable carrier.
More particularly, the invention relates to a pharmaceutical composition comprising an isolated peptide of the invention or a chimeric peptide of the invention, together with a pharmaceutically acceptable carrier.
The peptide is formulated in association with a pharmaceutically acceptable carrier.
The preparation of a pharmacological composition that contains active ingredients dissolved or dispersed therein is well understood in the art and need not be limited based on formulation. Typically such compositions are prepared as injectables either as liquid solutions or suspensions; however, solid forms suitable for solution, or suspensions, in liquid prior to use can also be prepared. The preparation can also be emulsified. In particular, the pharmaceutical compositions may be formulated in solid dosage form, for example capsules, tablets, pills, powders, dragees or granules.
The choice of vehicle and the content of active substance in the vehicle are generally determined in accordance with the solubility and chemical properties of the active compound, the particular mode of administration and the provisions to be observed in pharmaceutical practice. For example, excipients such as lactose, sodium citrate, calcium carbonate, dicalcium phosphate and disintegrating agents such as starch, alginic acids and certain complex silicates combined with lubricants such as magnesium stearate, sodium lauryl sulphate and talc may be used for preparing tablets. To prepare a capsule, it is advantageous to use lactose and high molecular weight polyethylene glycols. When aqueous suspensions are used they can contain emulsifying agents or agents which facilitate suspension. Diluents such as sucrose, ethanol, polyethylene glycol, propylene glycol, glycerol and chloroform or mixtures thereof may also be used.
The dosing is selected by the skilled person so that a anti-infectious effect is achieved, and depends on the route of administration and the dosage form that is used. Total daily dose of a peptide administered to a subject in single or divided doses may be in amounts, for example, of from about 0.001 to about 100 mg/kg body weight daily and preferably 0.01 to 10 mg/kg/day. Dosage unit compositions may contain such amounts of such submultiples thereof as may be used to make up the daily dose. It will be understood, however, that the specific dose level for any particular patient will depend upon a variety of factors including the body weight, general health, sex, diet, time and route of administration, rates of absorption and excretion, combination with other drugs and the severity of the particular disease being treated.
The isolated peptide and the chimeric peptide as defined above, the pharmaceutical composition of the invention may be used for treating Paramyxovirinae infection.
The invention thus also relates to a peptide, or a chimeric peptide of the invention for use for treating Paramyxovirinae infection.
In particular, the isolated peptide, or a chimeric peptide of the invention may have the ability to decrease the virus load in a subject of at least 50%, 60%, 70%, 80%, 90% or 100%.
The invention also provides a method of treatment of a Paramyxovirinae infection in a patient in need thereof, which method comprises administering said patient with an isolated peptide, or a chimeric peptide of the invention.
The Parmyxovirinae infection is due to a virus that belongs to the genus selected between Rubulavirus infection, Avulavivirus infection, Henipavirus infection, Henipavirus-like infection, Morbillivirus infection, Morbillivirus-like (TPMV-like viruses) infection or Ferlavirus infection
The Henipavirus infection is in particular but not limited to an infection with the Nipah virus (NiV) or with the Hendra virus (HeV).
The Morbillivirus infection is in particular but not limited to, an infection with the Measles virus (MeV) or Rinderpest virus.
The Rubulavirus infection is in particular but not limited to, an infection with the Mumps virus and parainfluenza type 2, 4 viruses.
The invention will be further illustrated by the following figures and examples. However, these examples and figures should not be interpreted in any way as limiting the scope of the present invention.
Figure 1: Structure of reconstituted NiV N0-P complex in solution and in crystal. (a) Schematic architecture of NiV N and P proteins. NNTD, N-terminal domain of N core; NCTD, C-terminal domain of N core; NTARM, N-terminal arm of N; CTARM, C-terminal arm of N; PNTR, N-terminal region of P; PCTR, C-terminal region of P; PMD, multimerization domain of P; PXD, C-terminal X domain of P. Boxes and lines show structured domains and intrinsically disordered regions, respectively. Arrows show the recombinant constructs used in this work. (b) Size exclusion chromatography (SEC) combined with on-line detection by multi-angle laser light scattering (MALLS) and refractometry (RI). The inset shows a Coomassie blue stained SDS-PAGE. The theoretical molecular mass calculated for a heterodimeric complex is 45,613 Da. (c) Difference intensity profile of 1H-15N HSQC spectra of 15N-labeled P100 in isolation and in complex with N0. (d) Fluoresence images of 293T transfected cells expressing NiV N, P40-wt peptide in fusion with GFP, or both proteins (bottom panels). Images are representative of one of three independent experiments. Scale bars (left panels) represent 10µm. (e) View of the crystal structure of NiV N32-3830-P50 complex with cartoon representation. N32-383 is shown together with P50. The location of some secondary structure elements and of the N-terminal arm and C-terminal arm and tail are indicated. The C- and N-terminal residues of the P fragment are indicated.
Figure 2: Comparison of NiV and RSV N proteins reveals an open-to-closed conformational change. (a) View of the structures of NiV N and RSV N (PDB code 2WJ8; ref 5) aligned in similar orientations. (b) Structural comparisons of NiV N32-383 in its crystal structure (left panel) and in a hypothetical closed conformation (right panel) with RSV N taken from the NC-like complex (PDB code 2WJ8; ref 5). NiV N32-383, RSV N and the RNA bound to RSV N are shown. The lines in the left panel show the direction of αN9 axis in each protein. The hypothetical closed form of NiV N was obtained by independently aligning NiV NNTD and NCTD on the corresponding domains of RSV N. (c) Front view of the RNA binding site in RSV N with a cartoon representation. Residues interacting with RNA and conserved in several members of the Paramyxovirinae (K170, R184, R185, R338 and Y337) are shown in stick representation. (d) Front view of the putative RNA binding groove of NiV N in its open and hypothetical closed conformations. The residues corresponding to those shown in Figure 2c are shown with stick representation (K178, R192, R193, R352 and Y354). (e) Side view of the RNA binding site in RSV N with a cartoon representation. Two glycine residues (G241 and G245) forming a flat surface on helix αN9 and interacting with base 1 of the six-nucleotide bound to each N protomer are shown in yellow. (f) Multiple sequence alignment among several members of the subfamily Paramyxovirinae: MeV, measles virus (Morbillivirus); MuV, mumps virus (Rubulavirus); NDV, Newcastle disease virus (Avulavirus). (g) Side view of the putative RNA binding groove of NiV N in its open and hypothetical closed conformations. The RNA molecule (shown) is docked against NiV NCTD as in RSV NC.
Figure 3: Conservation of the N0-P interface and inhibition of NiV replication by a N0-binding peptide of P. (a) View of the NiV N32-3830-P50 complex with surface and conservation representations for N32-383 and with cartoon and stick representations for P50. The conservation in N derived from multiple sequence alignment is displayed on the surface of NiV N. The sidechains of conserved residues in P N-terminal region are shown in stick representation. (b) Quantification of the effect of peptide expression on viral replication. Viral titer measured 48h after infection with NiV (MOI 0.01) in culture supernatant of 293T cells transfected with varying amounts (2 µg to 0.125 µg; bars 1 to 5) of plasmids coding for GFP alone (Control), P40-wt, P40-G10R or P40-I17R. Shown are means from three independent experiments. Error bars represent s.d. (n=6; ANOVA test: * indicates values for which P < 0.05). Ø indicates absence of plasmid. (c) Visual analysis of syncytia formation in NiV-infected cells expressing GFP (Control) or GFP-P40-w.t. or -P40-G10R. Arrows show examples of typical syncytia formation. Images are representative of those obtained in one of three independent experiments. Scale bars (left panels) represent 50µm.
Figure 4: Chaperone activities of NiV P. (a) Top view of one RSV N protomer within the N-RNA complex, shown with surface representation for NCORE aligned with NCTD of NiV N32-3830-P50 complex (PDB codes 2WJ8 and 4BKK; ref 5). The NTARM of the Ni-1 RSV N protomer and the CTARM of the Ni+1 RSV N protomer are shown with cartoon representation. Only P50 of the NiV complex is shown with cartoon representation. The inset shows the localization of RSV N protomer within the NC. (b) Front view of the same structural overlay. The inset shows the localization of RSV N protomer within the NC. (c) View of NiV P50 bound to NCTD in the N32-3830-P50 complex with cartoon representation. The latch in NCTD is shown. The Cα of residues making contacts between P50 and NCTD are shown for P50 or N32-3830 as spheres. Arrows indicate the connections between P50 and the helices αC1, ηC1, αC2 and αC4 of NCTD. (d) Multiple sequence alignment among several members of the subfamily Paramyxovirinae. (e) Structural overlay of RSV N-RNA complex and NiV N32-383 with cartoon representation. Residues Y258 and G305 of NiV N and residues Y251 and G295 of RSV N are shown with stick representation. The arrow indicates the hypothetical rotation of Y258 upon P release.
Figure 5: Inhibition of NiV or CDV replication by a N0-binding peptide of P. A. Peptides derived from the N0-binding region of P (P40) from NiV inhibit viral growth of both NiV and CDV. 293T cells were transfected with 1 µg of plasmid encoding either w.t. P40-CDV in fusion with GFP (P40-CDV), w.t. P40-NiV either in fusion with GFP (P40-NIV) or separately (pCG P40-NIV), GFP alone (MOCK) or no plasmid (NT). 24h later cells were infected with either NiV (black bars) or CDV (white bars) (MOI 0.01). Virus titers in culture supernatants were measured 48h after infection. B. Inhibition of CDV replication by both NiV- and CDV-derived peptides is dose-dependant. Cells were transfected as above with decreasing amounts of "P" plasmids ranging from 1 µg to 0.5 µg as indicated, or 1 µg of either GFP-encoding plasmid (MOCK) or empty plasmid (NT). 24h post-transfection cells were infected with CDV (MOI 0.01). Virus titers in culture supernatants were measured 72h after infection.
Material & Methods
 Reconstitution of the N0-P core complex.
Constructs comprising residues 1-50 (P50
) of P and residues 32-383 (N32-383
) or 32-402 of N (N32-402
) from the Malaysian isolate UMMC1 of Nipah virus (Uniprot numbers Q9IK91 and Q9IK92) were cloned in pETM40 vector in fusion with an N-terminal maltose binding protein (MBP) tag. All proteins were expressed in E. coli
BL21 (DE3) Rosetta cells. Cells were grown at 37 °C in LB medium until O.D. reached 0.6, and protein expression was induced overnight at 20°C by addition of isopropyl-β-D-thiogalactoside (IPTG) to a final concentration of 1 mM. Cells were harvested and the pellet was suspended in buffer A for P construct (20 mM Tris-HCl buffer at pH 7.5 containing 150 mM NaCl, 50 mM arginine, 50 mM glutamate and 0.5 mM tris(2-carboxyethyl)phosphine (TCEP)) and in buffer B for N constructs (Tris-HCl buffer at pH 7.5 containing 150 mM NaCl). All buffers were supplemented with Complete protease inhibitor cocktail (Roche). Cells were disrupted by sonication, and the crude extract was cleared by centrifugation at 45,000 g at 4°C for 20 min. The supernatant was loaded onto an amylose resin column (New England Biolabs) equilibrated in buffer A or B. The column was washed with 10 volumes of buffer A or B containing 500 mM NaCl and the protein was eluted with 50 mM maltose (Sigma) in buffer A or B.
The P-MBP fusion protein was cleaved with TEV protease to remove the MBP tag. The protease was added at an approximate weight ratio of 100:1 (fusion protein:TEV) and digest was performed in buffer A overnight at 4 °C. After concentration using Vivaspin concentrators (GE Healthcare) with a 3 kDa cut-off, the protein solution was loaded onto a S75 Superdex (GE Healthcare) column equilibrated in buffer A at 4°C. The purified P peptide was mixed with purified N-MBP, and the mixture was incubated overnight at 4 °C. After concentration, the solution was loaded onto a S75 Superdex column equilibrated in buffer A. The fractions containing the N0
-MBP-P complex were pooled, and the MBP tag was cleaved by incubation overnight at 4°C in the presence of TEV protease at a weight ratio of 100:1. The solution was concentrated and loaded onto a S75 Superdex (GE Healthcare) column coupled to a short amylose resin (NEB) column equilibrated in buffer B to completely remove cleaved MBP. The fractions containing the N0
-P complex were pooled and concentrated using Amicon concentrators (Millipore) with a 10 kDa cut-off. During the purification process, protein purity was checked by SDS-PAGE.
A construct comprising residues 1-100 (P100
) of P was cloned in pET28 vector with a C-terminal His-tag and expressed in E. coli
BL21 (DE3) Rosetta cells. To produce unlabeled P100
, cells were grown at 37 °C in LB medium until O.D. reached 0.6, and protein expression was induced overnight at 20°C by addition of isopropyl-β-D-thiogalactoside (IPTG) to a final concentration of 1 mM. For the 13
N labeled P100
, cells were grown in M9 minimal medium supplemented with MEM vitamins (Gibco), with 1.0 g.L-1
Cl and 4.0 g.L-1
C glucose as previously described24
. Cells were harvested and the pellet was suspended in buffer A supplemented with Complete protease inhibitor cocktail (Roche). Cells were disrupted by sonication, and the crude extract was cleared by centrifugation at 45,000 g at 4°C for 20 min. The supernatant was loaded onto His Select resin (Sigma) column pre-equilibrated in buffer A. The column was washed with 10 volumes of buffer A containing 500 mM NaCl and 10 mM imidazole (Sigma) and the protein was eluted in buffer A containing 300 mM imidazole. The fractions containing the peptide were pooled and concentrated using Vivaspin concentrators (GE Healthcare) with a 5 kDa cut-off. The solution was loaded onto a S200 Superdex column equilibrated in buffer A at 4°C. Fractions containing the peptide were pooled and concentrated. For NMR experiments, the N32-4020
complex was reconstituted as described above, and buffer A was exchanged with 20 mM Bis-Tris buffer at pH 6.0 containing 150 mM NaCl, 50 mM arginine, 50 mM glutamate and 0.5 mM TCEP.
To produce a selenomethionine substituted of N32-383
, cells were grown at 37°C in M9 minimal medium supplemented with MEM vitamins (Gibco), with 1.0 g.L-1
Cl and 2.0 g.L-1
of glucose until O.D. reached 0.6. Then, the temperature was lowered to 20°C and the culture was supplemented with a mix of amino acids containing 100 mg Lys, 100 mg Phe, 100 mg Thr, 50 mg Ile, 50 mg Leu, 50 mg Val and 50 mg SelenoMet per liter of medium and incubated for 45 minutes. Protein expression was induced overnight at 20°C by addition of isopropyl-β-D-thiogalactoside (IPTG) to a final concentration of 1 mM. The selenomethionine derivative was purified as described above.
 SEC-MALLS experiments.
Size exclusion chromatography (SEC) combined with on-line detection by multi-angle laser light scattering (MALLS) and refractometry (RI) is a method for measuring the absolute molecular mass of a particle in solution that is independent of its dimensions and shape25
. SEC was performed with a S200 Superdex column (GE Healthcare) equilibrated with 20 mM Tris-HCl buffer containing 150 mM NaCl. The column was calibrated with globular standard proteins. Separations were performed at 20°C with a flow rate of 0.5 mL.min-1
. On-line multiangle laser light scattering (MALLS) detection was performed with a DAWN-HELEOS II detector (Wyatt Technology Corp.) using a laser emitting at 690 nm, and protein concentration was measured on-line by the use of differential refractive index measurements using an Optilab T-rEX detector (Wyatt Technology Corp.) and a refractive index increment, dn
of 0.185 mL.g-1
. Weight-averaged molar masses (Mw) were calculated using the ASTRA software (Wyatt Technology Corp.). For size determination, the column was calibrated with proteins of known Stokes radius (Rs
 Small angle X-ray scattering experiments.
Small angle X-ray scattering (SAXS) data were collected at the BioSAXS beamline (BM29) of the ESRF (http:// www.esrf.eu/UsersAndScience/Experiments/MX/About_our_beamlines/BM29. The scattering from the buffer alone was measured before and after each sample measurement and was used for background subtraction using the program PRIMUS from the ATSAS package 27
. Scattering data were collected at different concentration ranging from 0.3 mg.mL-1
to 0.6 mg.mL-1
and from 0.55 mg.mL-1
to 2.4 mg.mL-1
-P complex. No concentration-dependent inter-particle effect was observed. Rg
was estimated at low Q values using the Guinier approximation. Ab initio
low-resolution bead models of the N0
-P complex were computed from the distance distribution function P(r) (Dmax
= 10 nm) using the program DAMMIN 28
. 20 low-resolution models, obtained from independent reconstructions, were aligned, averaged and filtered with the program DAMAVER29
. The crystal structure was docked within the envelop using the program SUPCOMB29
 NMR spectroscopy.
The spectral assignment of P100
of NiV P protein was obtained at 25°C in 20 mM Bis-Tris buffer at pH 6.0 containing 150 mM NaCl, 50 mM arginine, 50 mM glutamate and 0.5 mM TCEP using a set of BEST-type triple resonance experiments30
. The NMR experiments were acquired at a 1
H frequency of 800 MHz. A total of six experiments were acquired: HNCO, intra-residue HN(CA)CO, HN(CO)CA and intra-residue HNCA, HN(COCA)CB and intra-residue HN(CA)CB. All spectra were processed in NMRPipe31
, analyzed in Sparky32
and automatic assignment of spin systems was done using MARS33
followed by manual verification. The 1
N HSQC spectrum of P100
was compared to the spectrum of purified N32-3830
complex. The intensity ratio of the resonances in the two spectra was used for mapping the binding site of N° on P100
. Chemical shifts depend on the backbone φ and ψ dihedral angles, and in disordered systems, they are highly sensitive to the presence of transient secondary structure, commonly expressed in terms of a secondary structure propensity (SSP)34,35
. The SSP score for isolated P100
revealed the presence of several fluctuating α-helices.
We used different constructs of N and P to reconstitute N0
-P analogs, but only the N32-3830
complex crystallized. Initial crystallization conditions for the N32-3830
complex were identified at the High Throughput Crystallization Laboratory of the EMBL Grenoble Outstation (https://htxlab.embl.fr). Plate clusters obtained in 22% PEG 3350, 0.2M KBr were used to grow crystal of selenomethionine derivative of the N32-3830
complex by the microseeding method. A plate cluster of native protein was crushed in 50µl of stabilization solution (20 mM Tris HCl at pH 8 containing 22% PEG 3350, 0.2 M KBr and 0.2 M NaCl,) using the Seed Bead kit (Hampton Research). The seed stock was serially diluted (5, 25, 100, 1000 times), and the drops were set by mixing 0.5µl of the resulting seed stock, 1µl of protein solution and 1µl of precipitant solution. The crystals used for data collection were obtained with protein concentrations of 10 to 20 mg.mL-1
in the presence of 16-18% PEG 3350 and 0.2 M KBr and were frozen with 15% glycerol as cryo-protectant. X-ray diffraction data were collected at the ID29 beamline of the ESRF at a wavelength of 0.9793 Å and at a temperature of 100 K and were processed with the XDS package36
. Initial phases were obtained using the anomalous scattering from selenium atoms by the SAD method with the program HKL2MAP37
. A model was initially constructed with the Autobuild program38
from the phenix suite39
and subsequently refined with the phenix.refine program40
. The geometry of the final model was checked with MolProbity42
. In the model, 97.0% of residues have backbone dihedral angles in the favored region of the Ramachandran plot, 2.77% fall in the allowed regions and 0.23 % are outliers. Part of the αN5
loop is not visible in the crystal electron density. Figures have been generated with PyMol43
. Low frequency normal modes of N0
were computed with the Elastic Network Model45
. Multiple sequence alignments were performed with MAFFT46
 Plasmid construction.
Sequences corresponding to residues of NiV P, CDV P or MeV P were cloned in-frame with GFP into the pEGFP-C2 vector (CLONTECH Laboratories) to produce the construct pEGFP-P40 and derivatives (P6-40, P11-40; P1-20; P12-35 and P7-17 of NiV P and P1-22, P9-19 of CDV P and P9-19 of MeV P). NiV P variants P40-G10R and P40-I17R were obtained by site-directed mutagenesis using the QuickChange XL kit (Stratagene). The consensus peptide was produced by PCR cloning into the same pEGFP-C2 vector.
 Intracellular localization of N and P40
. HEK 293T cells were obtained from ATCC (HEK 293T/17 - ATCC CRL-11268). Cell lines were routinely assayed for mycoplasma contamination. 293T cells were cultured in Dulbecco's modified Eagle's medium (DMEM, PAA laboratories) supplemented with 10% fetal calf serum (FCS) (PerbioHyclone). For transfection, cells were grown for 24h to a confluence of ∼50% and were transfected with 0.5 µg of plasmid encoding N, GFP-P40-wt
or both (or empty plasmid as control) using Turbofect transfection reagent (Thermoscientific) at 4:1 ratios of reagent:DNA as recommended. After 48 hours, cells were fixed in 3.7% paraformaldehyde (PFA) in phosphate-buffered saline (PBS) for 45 min, then treated for 30 min with 50 mmol.L-1
Cl, and finally, for another 40 min in 0.1% Triton X100-PBS. Immunofluorescence of N was performed with an in-house henipavirus specific rabbit anti-N antibody (at a 1/1000 dilution, antibody specificity was determined by immunofluoresence as shown and by Western blot and Alexa Fluor 555 secondary antibody (Life Technologies) at a 1/1000 dilution. 4,6-diamindino-2-phenylindole
) diluted in PBS containing 1% bovine serum albumin (BSA) was used for nuclear staining. After several washing steps, pictures were taken using a Zeiss 200M fluorescent microscope. Images were analyzed by Axiovision Software (Zeiss) and ImageJ software47
 Inhibition of viral replication.
All experiments with the Nipah virus were performed at INSERM "Laboratoire Jean Merieux" (Lyon, France) in a biosafety level 4 (BSL-4) containment laboratory. HEK 293T cells were grown as described above for 24h to a confluence of ∼40%. Initially, the cells were transfected with plasmids encoding w.t. P40
in fusion with GFP, variants of P40
) in fusion with GFP or pEGFP alone as a control using Turbofect reagent as described above. In each case, the amount of plasmid was varied from 2 µg to 0.125 µg. 24h after transfection, cells were infected with NiV (Malaysian isolate UMMC1) at a multiplicity of infection (MOI) of 0.01. 1h post-infection (p.i.) virus inoculum was removed and replaced with DMEM media containing 3% FCS. Culture supernatants and cell lysates were collected at 48h p.i. for TCID50 titration and virus growth was assessed visually by inspecting for syncytial formation. Images of GFP fluorescence were taken using a Zeiss 200M fluorescent microscope. Images were analyzed by Axiovision Software (Zeiss). For Kärber TCID50 determination, serial ten-fold dilutions of viral culture supernatants were used to infect Vero E6 cells in the same way as described above and read 48h p.i. Significant differences were calculated using an ANOVA test where applicable, n=6.
Reconstitution of a functional NiV N0-P core complex
The inventors reconstituted several structural variants of NiV N0
-P complex using peptides encompassing the N0
-binding region of P and recombinant N molecules, truncated at the NTARM
and the CTARM
. By size exclusion chromatography (SEC) combined with multi-angle laser light scattering (MALLS) (Fig. 1b
) and by small-angle X-ray scattering (SAXS), we found that these reconstituted N0
-P core complexes are compact heterodimers with an overall bean-shape typical of other NNV N proteins18
The inventors mapped the region of P that directly interacts with N0
by nuclear magnetic resonance (NMR) spectroscopy. To this purpose, we expressed and purified a peptide of 100 amino acids corresponding to the N-terminal region of P (P100
) and characterized its structural properties. By SEC-MALLS, we showed that the peptide is monomeric in solution and that both its hydrodynamic radius measured by SEC and its radius of gyration measured by SAXS were larger than expected for a globular protein of this molecular mass. In addition, the poor chemical shift dispersion of amide resonances in the heteronuclear single quantum coherence (HSQC) NMR spectrum was typical of disordered protein, but after assigning the NMR spectrum, the secondary structure propensity (SSP) parameter calculated from Cα and Cβ secondary chemical shifts, indicated the presence of five fluctuating α-helices. We then analyzed the HSQC spectrum of P100 bound to N32-383
. In a complex of this size (∼50 kDa), NMR signals are strongly broadened in protonated samples, precluding their detection, but in the HSQC spectrum we observed resonances corresponding to residues 50 to 100, indicating that this region remains flexible in the complex and that the N0
-binding region is comprised within the first fifty N-terminal amino acids of P (Fig. lc).
Accordingly, The inventors demonstrated that a peptide corresponding to the first forty residues of P (P40
) is sufficient to maintain N in a soluble form in vitro (Fig. Id).
In human cells expressing NiV N alone, we observed a punctuate distribution that can be attributed to the inherent self-assembly properties of the protein. In cells co-expressing both N and GFP-fused P40
-GFP) in a 1:1 ratio, we observed a notably homogenous distribution of N in the cell and the colocalization of N with P40
, suggesting that the N0
complex forms in the intracellular environment and leads to the solubilization of N (Fig. Id).
Crystal structure of NiV N0-P core complex
The NiV N32-3830
complex crystallized in space group P21
with three heterodimers in the asymmetric unit. We determined the structure at 2.5 Å resolution by the SAD method (Fig. 1e).
NiV N exhibited the two-domain structure characteristic of NNV N5-8
, defining a basic groove that can bind RNA. Despite the overall low sequence conservation, the N core could be divided into four different parts, NNTD1
, of which three appear to have a conserved fold among different NNV families (Fig. 2a)5-7,19
. On the basis of their localization in the structure, we defined ten motifs conserved among most members of the Paramyxovirinae
and assigned them structural or functional roles.
The N-terminal chaperone region of P is stabilized upon binding to its N0
partner, but only the first 35 residues of P, corresponding to the first fluctuating helix observed in solution (helix αP1
), were visible in the crystal structure of the N32-3830
complex. In the complex, this region formed a 2.9 nm-long helix (helix αP1a
: aa 1-19) with a 90° kink at residue N20 leading to a short helix (helix αP1b
: aa 21-28) (Fig. 1e.
The long helix αP1a
docked to a shallow hydrophobic groove of NCTD
formed by helices αC1
of conserved motif 6 (aa 265-305), and the short helix docks to the top of NCTD
(motif 10) (Fig. 1e.
The complex involves multiple hydrophobic contacts and eight hydrogen bonds for a total surface area buried in the interaction of 1,440 Å2
NiV N is in an open conformation in N0-P complex
By comparing the structure of NiV N32-3830
with that of RSV N in complex with RNA5
, we found that the fold of N is conserved (Fig. 2a
but that the putative RNA binding groove of NiV N0
is open, with NNTD
bowing down by about 30° from NCTD (Fig. 2b).
We observed that a Tyr residue (Y337) and four out of the five basic residues (K170, R184, R185, R338 and R342) interacting with RNA in RSV N (Fig. 2c)
are present at equivalent positions (Y354 and K178, R192, R193, R352, respectively) in the helix αN5
, the αN5
loop, the helix αN6
and the αC3
loop of NiV N (Fig. 2D)
and are conserved among Paramyxovirinae.
However, they are too far apart in NiV N0
to concurrently interact with a RNA molecule. Independent 3D alignments of NiV NNTD
with RSV N brought these residues into similar positions in both proteins (Fig. 2b and 2d),
suggesting a common mechanism of conformational switching between open and closed conformations that involves a hinge motion between NCTD
, in agreement with normal mode simulations .
RNA binding and the rule of six
In RSV NCs, each N interacts with seven nucleotides (nt) and base 1 packs on the flat surface of helix αN9
formed by two glycine residues (G241 and G245) (Fig. 2e)5
. However, in the Paramyxovirinae
sub-family, N binds to only six nt and the genome obeys a rule of six, i.e.
a strict requirement for their genome to consist of a multiple of six nt20,21
. In the putative closed form of NiV N, we found that several residues in helix αN6
(conserved motif 3) (Fig. 2f)
and D254 in helix αN9
(conserved motif 5) hinder a similar packing of base 1 (Fig. 2g).
The presence of motif 3, which is strictly conserved in the Paramyxovirinae
sub-family, but is absent in the Pneumovirinae
subfamily, might thus explain why the N protein of the Paramyxovirinae
binds only six nt and why these viruses obey the rule of six.
Conservation of the N0-P binding interface
NNV phosphoproteins vary greatly in length and amino acid sequence22
, with sequence conservation generally becoming undetectable beyond the family level. However, a recent study identified residues in the N-terminal region of P that are conserved among most members of the Paramyxoviridae
in spite of an overall distant evolutionary relationship23
. Most of these conserved residues appeared to be key residues for the interaction with N0 (Fig. 3a),
whereas mapping residue conservation among Paramyxovirinae
onto the surface of NiV N reveals a strong conservation of the binding site for P (Fig. 3a).
These results thus suggest a conserved structural architecture of the N0
-P complex among different genera of the subfamily, and broaden the scope of our NiV N0
-P core structure.
Inhibition of NiV replication
The inventors found that expression of GFP-fused P40
peptide in human cells (HEK293T) prior to infection significantly inhibits viral growth in a dose-dependent manner and abolishes syncytia formation, the latter being a hallmark of NiV infection (Fig. 3b-c).
We used the N32-3830
crystal structure to design peptide variants that destabilize the interface between N0
, and found that the variants in which conserved residues G10 or 117 are mutated to arginine (G10R, I17R) were less efficient in inhibiting viral replication. These results thus supported the specificity of the interaction observed in the crystal (Fig. 3b-c).
Because the reconstituted N0
-P core complex lacks a large part of the P molecule, notably the tetramerization domain and both polymerase and NC binding regions, we hypothesized that P40
might inhibit viral growth by trapping N0
in a non-productive complex.
The chaperone functions of P
To understand the chaperone functions of PNTR
, we used RSV N-RNA complex as a model for NiV N-RNA complex (Fig. 4a, 4b).
When we aligned NCTD
of NiV N32-3830
with the NCTD
of one N protomer of the RSV N-RNA complex, we discovered that helix αP1b
competes with the CTARM
of the Ni+1
protomer for the same binding site on N surface (Fig. 4a),
whereas helix αP1a
competes with the NTARM
of the Ni-1
protomer (Fig. 4b).
A first role of P is thus to prevent the polymerization of N by interfering with the binding of exchanged subdomains. The structure of NiV N32-3830
complex also suggested that bound P prevents NC assembly and RNA binding by trapping N0
in an open conformation without directly interfering with RNA (Fig. 2g).
The closure of the molecule requires that helices αN5
rotate around pivots near the NNTD
junction (Fig. 2b)
and thereby that the latch formed by helices αC2
move away from the NCTD
core. We propose that by bridging helices αC1
and αC4 (Fig. 4c),
P rigidifies the entire NCTD
domain and prevents global conformational changes in N. In addition, the bulky side chain of Y258, a highly conserved residue among Paramyxoviridae (Fig. 4d),
points inside the RNA binding groove preventing the RNA from coming into close contact with the surface of the protein (Fig. 4e).
In the RSV N-RNA complex, Y251, similarly located at the end of helix αN9
, points in the opposite direction and docks against the backbone of a glycine residue in helix αC2
. A glycine is also conserved at this position in NiV N suggesting that the tyrosine side chain flips away upon RNA binding (Fig. 4e),
but in the N0
-P complex, motion of Y258 is hindered by the presence of the N-terminal end of P. Alternatively, Y258 might interact with one of the RNA bases.
The inventors present the structure of the N0
-P core complex of Nipah virus, revealing that unassembled N0
is maintained in an open conformation and providing experimental evidence that NNV N switches between open and closed conformations during NC assembly. In the N0
-P complex, the N-terminal N0
-binding region of P prevents N polymerization by occupying the binding sites for the exchanged subdomains of adjacent N and prevents RNA encapsidation by bridging NCTD
and hindering closure of the molecule. We propose a possible scenario for the assembly of N° molecules along newly synthesized viral RNA by a concerted mechanism of transfer of N° from the N0
-P complex to the nascent RNA molecule, which involves the release of P and the closure of the RNA binding groove. In a first step, we assume that encounter complex forms with the RNA molecule loosely inserted in the open cavity. In a second concerted step, P is released and N grasps the RNA molecule. The release of P from the RNA-bound N liberates the binding site for the NT-arm of the next incoming N molecule. Upon formation of the encounter complex with the next N0
-P complex, the NTARM
of the incoming N can bind to the previously bound N. The CTARM
of bound N can bind to the incoming N and help in displacing the P peptide. In a second or concomitant process, P is released and N closes on the RNA. The NTARM
of the first bound N molecule locks the second N in its closed conformation by bridging NNTD
The inventors confirmed that the short N0
-binding region of P is sufficient to chaperone N0
and to keep it in a soluble form, but P40
inhibited viral replication, indicating that the N-terminal region of P is not sufficient to enable NC assembly and suggesting the involvement of other regions of P in this process. P is a multifunctional, highly flexible molecule, which also possesses binding sites for L or for NCs, and it is thus plausible that interactions with these other viral proteins are necessary to correctly positionthe N0
-P complex at the site of viral RNA synthesis. The attachment of N0
-P to the NC, as suggested in Figure 5c would raise the local concentration around the site of RNA synthesis and thereby favor the encapsidation of the viral RNA.
The successful inhibition of NiV infection by the N0
-binding peptide of P suggests that the P binding cavity in N can be specifically targeted for designing inhibitors of NiV replication. The structure of the N0
-P core complex provides the structural basis for designing small molecules that could prevent the formation of the complex. The strong conservation of the binding interface suggests that NiV N32-3830
structure is a good structural model for the N0
-P complex of other medically-relevant paramyxoviruses and that possibly a broad spectrum drug might be developed against several viruses.
Materials and Methods:
 Plasmid construction.
Sequences corresponding to residues of NiV P or CDV P (reference strain, Genbank NC_001921.1) were either cloned in-frame with GFP into the pEGFP-C2 vector (CLONTECH Laboratories) to produce the constructs pEGFP-P40-NIV and pEGFP-P40-CDV, or into the vector pCG (ref -Differential transcriptional activation by Oct-1 and Oct-2: interdependent activation domains induce Oct-2 phosphorylation. Tanaka M, Herr W. Cell. 1990 Feb 9;60(3):375-86
. 10.1016/0092-8674(90)90589-7) containing a GFP-IRES-multicloning site. This vector allows the simultaneous expression of both GFP and p40 peptide separately but from the same bi-cistronic RNA transcript after transfection into mammalian cells.
 Inhibition of viral replication with NIV and CDV.
293T cells were cultured in Dulbecco's modified Eagle's medium (DMEM, PAA laboratories) supplemented with 10% fetal calf serum (FCS) (PerbioHyclone). All experiments with the Nipah virus were performed at INSERM "Laboratoire Jean Mérieux" (Lyon, France) in a biosafety level 4 (BSL4) containment laboratory. All experiments with the canine distemper virus were performed at under biosafety level 2 confinement in a cell culture biosafety cabinet reserved for work with infectious material. Cells were grown as described above for 24h to a confluence of ∼40%. Initially, the cells were transfected with plasmids encoding w.t. P40
-NIV in fusion with GFP (pEGFP vector) or expressed separately (from the pCG bi-cistronic IRES vector, described above), or w.t. P40
-CDV in fusion with GFP (pEGFP vector) or either pEGFP/pCG alone as control, using Turbofect following manufacturer's recommendations. 24h after transfection, cells were infected with either NiV (Malaysian isolate UMMC1) or CDV at a multiplicity of infection (MOI) of 0.01. 1h post-infection (p.i.) virus inoculum was removed and replaced with DMEM media containing 3% FCS. Culture supernatants and cell lysates were collected at 48h p.i. for TCID50 titration and virus growth was assessed visually by inspecting for syncytial formation. Pictures of GFP fluorescence were taken using a Zeiss 200M fluorescent microscope. Images were analyzed by Axiovision Software (Zeiss). For Kärber TCID50 determination, serial ten-fold dilutions of viral culture supernatants were used to infect Vero E6 cells in the same way as described above and read 48-72h p.i.
Inhibition of NiV or CDV replication by a N0-binding peptide of P.
The inventors demonstrated that peptides derived from the N0
-binding region of P (P40
) from NiV inhibit viral growth of both NiV and CDV (Figure 5A). The inventors also demonstrated that the inhibition of CDV replication by both NiV- and CDV-derived peptides is dose-dependant (Figures 5B).
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<120> PEPTIDES INCLUDING A BINDING DOMAIN OF THE VIRAL PHOSPHOPROTEIN (P) SUBUNIT TO THE VIRAL NUCLEOPROTEIN (N0)
<130> BIO14104 VOLCHKOV
<170> PatentIn version 3.3
<223> Pl-40 Nipah
<223> Pl-40 CDV
<223> consensus peptide
<223> Pl-40 MeV
<223> TAT peptide 2
<223> Tat peptide
<223> Polyarginine peptide R9
<223> Polyarginine peptide R11
<223> HA2-R9 peptide
<223> Penetratin peptide
<223> Transportan peptide
<223> Maurocalcine peptide
<223> decalysine peptide
<223> HIV-Tat derived PTD4 peptide
<223> Hepatitis B virus Translocation Motif (PTM) peptide
<223> mPrPl-28 peptide
<223> POD peptide
<223> pVEC peptide
<223> EB1 peptide
<223> Rath peptide
<223> CADY peptide
<223> Histatin 5 peptide
<223> Antp peptide
<223> Cyt86-101 peptide
<223> DPT peptide
<223> P40 Nipah nucleotidic sequence
<223> P40 CDV nucleotidic sequence
<223> P40 MeV nucleotidic sequence
<223> N189-205 Nipah
<223> N191-207 Mev
<223> N191-207 Muv
<223> N189-205 NDV
<223> N253-273 Nipah
<223> N253-273 Mev
<223> N253-273 Muv
<223> N251-271 NDV