View source for 4qr0


==Crystal structure of Streptococcus pyogenes Cas2 at pH 5.6==
<StructureSection load='4qr0' size='340' side='right'caption='[[4qr0]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4qr0]] is a 2 chain structure with sequence from [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=4QR0 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4QR0 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]] 2.4&#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=4qr0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4qr0 OCA], [https://pdbe.org/4qr0 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4qr0 RCSB], [https://www.ebi.ac.uk/pdbsum/4qr0 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4qr0 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/Q99YS8_STRP1 Q99YS8_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 sequences complementary to antecedent mobile elements and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). Functions as a ssRNA-specific endoribonuclease. Involved in the integration of spacer DNA into the CRISPR cassette.[HAMAP-Rule:MF_01471]
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== Publication Abstract from PubMed ==
Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins constitute an RNA-guided microbial defense system against invading foreign genetic materials. Cas2 is one of the core Cas proteins found universally in all the subtypes of CRISPR-Cas systems and is required for incorporating new spacers into CRISPR loci. Cas2 homologues from different CRISPR-Cas subtypes were characterized previously as metal-dependent nucleases with different substrate preferences, and it was proposed that a pH-dependent conformational change mediates metal binding and catalysis. Here, we report the crystal structures of Streptococcus pyogenes Cas2 at three different pHs (5.6, 6.5, and 7.5), as well as the results of its nuclease activity assay against double-stranded DNAs at varying pHs (6.0-9.0). Although S. pyogenes Cas2 exhibited strongly pH-dependent catalytic activity, there was no significant conformational difference among the three crystal structures. However, structural comparisons with other Cas2 homologues revealed structural variability and the flexible nature of its putative hinge regions, supporting the hypothesis that conformational switching is important for catalysis. Taken together, our results confirm that Cas2 proteins have pH-dependent nuclease activity against double-stranded DNAs, and provide indirect structural evidence for their conformational changes.

Structural and functional characterization of Streptococcus pyogenes Cas2 protein under different pH conditions.,Ka D, Kim D, Baek G, Bae E Biochem Biophys Res Commun. 2014 Aug 15;451(1):152-7. doi:, 10.1016/j.bbrc.2014.07.087. Epub 2014 Jul 29. PMID:25079131<ref>PMID:25079131</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4qr0" style="background-color:#fffaf0;"></div>

==See Also==
*[[Endonuclease 3D structures|Endonuclease 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Streptococcus pyogenes serotype M1]]
[[Category: Bae E]]
[[Category: Ka D]]
[[Category: Kim D]]