View source for 5f22

==C-terminal domain of SARS-CoV nsp8 complex with nsp7==
<StructureSection load='5f22' size='340' side='right' caption='[[5f22]], [[Resolution|resolution]] 2.15&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5f22]] is a 2 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5F22 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5F22 FirstGlance]. <br>
</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5f22 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5f22 OCA], [http://pdbe.org/5f22 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5f22 RCSB], [http://www.ebi.ac.uk/pdbsum/5f22 PDBsum]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/R1A_CVHSA R1A_CVHSA]] The papain-like proteinase (PL-PRO) is responsible for the cleavages located at the N-terminus of replicase polyprotein. In addition, PL-PRO possesses a deubiquitinating/deISGylating activity and processes both 'Lys-48'- and 'Lys-63'-linked polyubiquitin chains from cellular substrates. Antagonizes innate immune induction of type I interferon by blocking the phosphorylation, dimerization and subsequent nuclear translocation of host IRF-3.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>   The main proteinase 3CL-PRO is responsible for the majority of cleavages as it cleaves the C-terminus of replicase polyprotein at 11 sites. Recognizes substrates containing the core sequence [ILMVF]-Q-|-[SGACN]. Inhibited by the substrate-analog Cbz-Val-Asn-Ser-Thr-Leu-Gln-CMK (By similarity). Also contains an ADP-ribose-1''-phosphate (ADRP)-binding function.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>   Nsp7-nsp8 hexadecamer may possibly confer processivity to the polymerase, maybe by binding to dsRNA or by producing primers utilized by the latter.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>   Nsp9 is a ssRNA-binding protein.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>  [[http://www.uniprot.org/uniprot/R1AB_CVHSA R1AB_CVHSA]] The replicase polyprotein of coronaviruses is a multifunctional protein: it contains the activities necessary for the transcription of negative stranded RNA, leader RNA, subgenomic mRNAs and progeny virion RNA as well as proteinases responsible for the cleavage of the polyprotein into functional products (By similarity).<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>   The papain-like proteinase (PL-PRO) is responsible for the cleavages located at the N-terminus of replicase polyprotein. In addition, PL-PRO possesses a deubiquitinating/deISGylating activity and processes both 'Lys-48'- and 'Lys-63'-linked polyubiquitin chains from cellular substrates. Antagonizes innate immune induction of type I interferon by blocking the phosphorylation, dimerization and subsequent nuclear translocation of host IRF-3.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>   The main proteinase 3CL-PRO is responsible for the majority of cleavages as it cleaves the C-terminus of replicase polyprotein at 11 sites. Recognizes substrates containing the core sequence [ILMVF]-Q-|-[SGACN]. Inhibited by the substrate-analog Cbz-Val-Asn-Ser-Thr-Leu-Gln-CMK (By similarity). Also contains an ADP-ribose-1''-phosphate (ADRP)-binding function.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>   The helicase which contains a zinc finger structure displays RNA and DNA duplex-unwinding activities with 5' to 3' polarity. Its ATPase activity is strongly stimulated by poly(U), poly(dT), poly(C), poly(dA), but not by poly(G). Activity of helicase is dependent on magnesium.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>   The exoribonuclease acts on both ssRNA and dsRNA in a 3' to 5' direction.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>   Nsp7-nsp8 hexadecamer may possibly confer processivity to the polymerase, maybe by binding to dsRNA or by producing primers utilized by the latter.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>   Nsp9 is a ssRNA-binding protein.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>   NendoU is a Mn(2+)-dependent, uridylate-specific enzyme, which leaves 2'-3'-cyclic phosphates 5' to the cleaved bond.<ref>PMID:17024178</ref> <ref>PMID:17692280</ref> <ref>PMID:19369340</ref>  
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
During severe acute respiratory syndrome coronavirus (SARS-CoV) infection, the activity of the replication/transcription complexes (RTC) quickly peaks at 6 hours post infection (h.p.i) and then diminishes significantly in the late post-infection stages. This "down-up-down" regulation of RNA synthesis distinguishes different viral stages: primary translation, genome replication, and finally viron assembly. Regarding the nsp8 as the primase in RNA synthesis, we confirmed that the proteolysis product of the primase (nsp8) contains the globular domain (nsp8C), and indentified the resectioning site that is notably conserved in all the three groups of coronavirus. We subsequently crystallized the complex of SARS-CoV nsp8C and nsp7, and the 3-D structure of this domain revealed its capability to interfuse into the hexadecamer super-complex. This specific proteolysis may indicate one possible mechanism by which coronaviruses to switch from viral infection to genome replication and viral assembly stages.

New nsp8 isoform suggests mechanism for tuning viral RNA synthesis.,Li S, Zhao Q, Zhang Y, Zhang Y, Bartlam M, Li X, Rao Z Protein Cell. 2010 Feb;1(2):198-204. doi: 10.1007/s13238-010-0028-8. Epub 2010, Feb 6. PMID:21203988<ref>PMID:21203988</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5f22" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Li, S]]
[[Category: Complex]]
[[Category: Hydrolase]]
[[Category: Primase]]