View source for 6ifo


==Crystal structure of AcrIIA2-SpyCas9-sgRNA ternary complex==
<StructureSection load='6ifo' size='340' side='right'caption='[[6ifo]], [[Resolution|resolution]] 3.31&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6ifo]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Listeria_monocytogenes Listeria monocytogenes], [https://en.wikipedia.org/wiki/Streptococcus_pyogenes_M1_GAS Streptococcus pyogenes M1 GAS] and [https://en.wikipedia.org/wiki/Streptococcus_pyogenes_serotype_M1 Streptococcus pyogenes serotype M1]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6IFO OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6IFO 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]] 3.313&#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=6ifo FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6ifo OCA], [https://pdbe.org/6ifo PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6ifo RCSB], [https://www.ebi.ac.uk/pdbsum/6ifo PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6ifo 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> 
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== Publication Abstract from PubMed ==
CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated proteins) systems provide prokaryotic cells with adaptive immunity against invading bacteriophages. Bacteriophages counteract bacterial responses by encoding anti-CRISPR inhibitor proteins (Acr). However, the structural basis for their inhibitory actions remains largely unknown. Here, we report the crystal structure of the AcrIIA2-SpyCas9-sgRNA (single-guide RNA) complex at 3.3 A resolution. We show that AcrIIA2 binds SpyCas9 at a position similar to the target DNA binding region. More specifically, AcrIIA2 interacts with the protospacer adjacent motif (PAM) recognition residues of Cas9, preventing target double-stranded DNA (dsDNA) detection. Thus, phage-encoded AcrIIA2 appears to act as a DNA mimic that blocks subsequent dsDNA binding by virtue of its highly acidic residues, disabling bacterial Cas9 by competing with target dsDNA binding with a binding motif distinct from AcrIIA4. Our study provides a more detailed mechanistic understanding of AcrIIA2-mediated inhibition of SpyCas9, the most widely used genome-editing tool, opening new avenues for improved regulatory precision during genome editing.

Phage AcrIIA2 DNA Mimicry: Structural Basis of the CRISPR and Anti-CRISPR Arms Race.,Liu L, Yin M, Wang M, Wang Y Mol Cell. 2019 Feb 7;73(3):611-620.e3. doi: 10.1016/j.molcel.2018.11.011. Epub, 2018 Dec 31. PMID:30606466<ref>PMID:30606466</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 6ifo" style="background-color:#fffaf0;"></div>

==See Also==
*[[Endonuclease 3D structures|Endonuclease 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Listeria monocytogenes]]
[[Category: Streptococcus pyogenes M1 GAS]]
[[Category: Streptococcus pyogenes serotype M1]]
[[Category: Liu L]]
[[Category: Wang Y]]