View source for 8ye9


==Cryo-EM structure of Cas9-sgRNA-A25 complex==
<StructureSection load='8ye9' size='340' side='right'caption='[[8ye9]], [[Resolution|resolution]] 3.43&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8ye9]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Streptococcus_pyogenes Streptococcus pyogenes], [https://en.wikipedia.org/wiki/Streptococcus_pyogenes_serotype_M1 Streptococcus pyogenes serotype M1] and [https://en.wikipedia.org/wiki/Streptococcus_sp._F0441 Streptococcus sp. F0441]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8YE9 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8YE9 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.43&#8491;</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=8ye9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8ye9 OCA], [https://pdbe.org/8ye9 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8ye9 RCSB], [https://www.ebi.ac.uk/pdbsum/8ye9 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8ye9 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CAS9_STRP1 CAS9_STRP1] CRISPR (clustered regularly interspaced short palindromic repeat) is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain spacers, sequences complementary to antecedent mobile elements, and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA) (Probable). In type II CRISPR systems correct processing of pre-crRNA requires a trans-encoded small RNA (tracrRNA), endogenous ribonuclease 3 (rnc) and this protein. The tracrRNA serves as a guide for ribonuclease 3-aided processing of pre-crRNA. Subsequently Cas9/crRNA/tracrRNA endonucleolytically cleaves linear or circular dsDNA target complementary to the spacer. The target strand not complementary to crRNA is first cut endonucleolytically, then trimmed by 3'-5' exonucleolytically. DNA-binding requires protein and both RNA species. Cas9 probably recognizes a short motif in the CRISPR repeat sequences (the PAM or protospacer adjacent motif) to help distinguish self versus nonself.<ref>PMID:21455174</ref> <ref>PMID:22745249</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
In the ongoing arms race between bacteria and bacteriophages, bacteriophages have evolved anti-CRISPR proteins to counteract bacterial CRISPR-Cas systems. Recently, AcrIIA25.1 and AcrIIA32 have been found to effectively inhibit the activity of SpyCas9 both in bacterial and human cells. However, their molecular mechanisms remain elusive. Here, we report the cryo-electron microscopy structures of ternary complexes formed by AcrIIA25.1 and AcrIIA32 bound to SpyCas9-sgRNA. Using structural analysis and biochemical experiments, we revealed that AcrIIA25.1 and AcrIIA32 recognize a novel, previously-unidentified anti-CRISPR binding site on SpyCas9. We found that both AcrIIA25.1 and AcrIIA32 directly interact with the WED domain, where they spatially obstruct conformational changes of the WED and PI domains, thereby inhibiting SpyCas9 from recognizing protospacer adjacent motif (PAM) and unwinding double-stranded DNA. In addition, they may inhibit nuclease activity by blocking the dynamic conformational changes of the SpyCas9 surveillance complex. In summary, our data elucidate the inhibition mechanisms of two new anti-CRISPR proteins, provide new strategies for the modulation of SpyCas9 activity, and expand our understanding of the diversity of anti-CRISPR protein inhibition mechanisms.

Inhibition mechanisms of CRISPR-Cas9 by AcrIIA25.1 and AcrIIA32.,Zheng J, Zhu Y, Huang T, Gao W, He J, Huang Z Sci China Life Sci. 2024 Sep;67(9):1781-1791. doi: 10.1007/s11427-024-2607-8. , Epub 2024 Jun 4. PMID:38842649<ref>PMID:38842649</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 8ye9" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Streptococcus pyogenes]]
[[Category: Streptococcus pyogenes serotype M1]]
[[Category: Streptococcus sp. F0441]]
[[Category: Huang Z]]
[[Category: Zheng J]]
[[Category: Zhu Y]]