View source for 3zdp


==R416A Monomeric nucleoprotein of influenza A virus==
<StructureSection load='3zdp' size='340' side='right'caption='[[3zdp]], [[Resolution|resolution]] 2.69&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3zdp]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Influenza_A_virus Influenza A virus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ZDP OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3ZDP FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.69&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=K:POTASSIUM+ION'>K</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3zdp FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3zdp OCA], [https://pdbe.org/3zdp PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3zdp RCSB], [https://www.ebi.ac.uk/pdbsum/3zdp PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3zdp ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/NCAP_I33A0 NCAP_I33A0] Encapsidates the negative strand viral RNA, protecting it from nucleases. The encapsidated genomic RNA is termed the ribonucleoprotein (RNP) and serves as template for transcription and replication. The RNP needs to be localized in the nucleus to start an infectious cycle, but is too large to diffuse through the nuclear pore complex. NP comprises at least 2 nuclear localization signals and is responsible of the active RNP import into the nucleus through the cellular importin alpha/beta pathway. Later in the infection, nucleus export of RNP are mediated through viral proteins NEP interacting with M1 which binds nucleoproteins. It is possible that the nucleoprotein binds directly exportin-1 (XPO1) and plays an active role in RNP nuclear export. M1 interaction with RNP seems to hide nucleoprotein's nuclear localization signals. Soon after a virion infects a new cell, M1 dissociates from the RNP under acidification of the virion driven by M2 protein. Dissociation of M1 from RNP unmask nucleoprotein's nuclear localization signals, targeting the RNP to the nucleus (By similarity).
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== Publication Abstract from PubMed ==
Isolated influenza A virus nucleoprotein exists in an equilibrium between monomers and trimers. Samples containing only monomers or only trimers can be stabilized by respectively low and high salt. The trimers bind RNA with high affinity but remain trimmers, whereas the monomers polymerise onto RNA forming nucleoprotein-RNA complexes. When wild type (wt) nucleoprotein is crystallized, it forms trimers, whether one starts with monomers or trimers. We therefore crystallized the obligate monomeric R416A mutant nucleoprotein and observed how the domain exchange loop that leads over to a neighbouring protomer in the trimer structure interacts with equivalent sites on the mutant monomer surface, avoiding polymerisation. The C-terminus of the monomer is bound to the side of the RNA binding surface, lowering its positive charge. Biophysical characterization of the mutant and wild type monomeric proteins gives the same results, suggesting that the exchange domain is folded in the same way for the wild type protein. In a search for how monomeric wt nucleoprotein may be stabilized in the infected cell we determined the phosphorylation sites on nucleoprotein isolated from virus particles. We found that serine 165 was phosphorylated and conserved in all influenza A and B viruses. The S165D mutant that mimics phosphorylation is monomeric and displays a lowered affinity for RNA compared with wt monomeric NP. This suggests that phosphorylation may regulate the polymerisation state and RNA binding of nucleoprotein in the infected cell. The monomer structure could be used for finding new anti influenza drugs because compounds that stabilize the monomer may slow down viral infection.

Monomeric nucleoprotein of influenza a virus.,Chenavas S, Estrozi LF, Slama-Schwok A, Delmas B, Di Primo C, Baudin F, Li X, Crepin T, Ruigrok RW PLoS Pathog. 2013 Mar;9(3):e1003275. doi: 10.1371/journal.ppat.1003275. Epub 2013, Mar 28. PMID:23555270<ref>PMID:23555270</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 3zdp" style="background-color:#fffaf0;"></div>

==See Also==
*[[Nucleoprotein 3D structures|Nucleoprotein 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Influenza A virus]]
[[Category: Large Structures]]
[[Category: Chenavas S]]
[[Category: Crepin T]]
[[Category: Ruigrok RWH]]