View source for 21bh


==Cryo-EM structure of type VII CRISPR-Cas complex at the target engagement state==
<StructureSection load='21bh' size='340' side='right'caption='[[21bh]], [[Resolution|resolution]] 3.10&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[21bh]] is a 14 chain structure with sequence from [https://en.wikipedia.org/wiki/Metagenome Metagenome]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=21BH OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=21BH 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]] 3.1&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ZN:ZINC+ION'>ZN</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=21bh FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=21bh OCA], [https://pdbe.org/21bh PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=21bh RCSB], [https://www.ebi.ac.uk/pdbsum/21bh PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=21bh ProSAT]</span></td></tr>
</table>
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== Publication Abstract from PubMed ==
Type VII CRISPR-Cas system, evolutionarily associated with type III systems, utilizes a Cascade complex formed by Cas5 and catalytically inactive Cas7 copies for target RNA binding, but instead incorporates a specialized Cas14 ribonuclease for target cleavage. Here, we report a high-quality cryo-EM structure at the target engagement state with a shortened crRNA and elucidate how the recruited Cas14 captures the target RNA and undergoes target-mediated activation. The signature Cas14 is homologous to eukaryotic CPSF73 and prokaryotic RNase J, comprising two conserved subdomains, MbetaL and beta-CASP. Different from canonical type III systems, 5'-end target RNA, rather than 3'-end, is bent into the positively charged binding channel formed by the two subdomains to access the conserved catalytic pocket on Cas14. Two special structural features, alpha1 helix from Cas7 and alpha10 helix from Cas14, promote the bent target RNA docking into the catalytic pocket of Cas14 nuclease in concert. A dual-functional loop, displaced by the entering target RNA, induces a closed-to-open transition between the two subdomains for nuclease activation. More importantly, the flipped dual-functional loop also maintains the stabilization of incoming target RNA. Altogether, our work provides a more comprehensive understanding of type VII system mechanism, laying a mechanistic foundation for RNA-targeting tool development.

Allosteric activation mechanism of the type VII CRISPR-Cas system.,Zhang S, Liu Y, Wu W, Liu Z, He Q, Wang T, Yang J, Yin H, Yuan Z, Zhang H Nucleic Acids Res. 2026 Mar 19;54(6):gkag314. doi: 10.1093/nar/gkag314. PMID:41954985<ref>PMID:41954985</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 21bh" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Metagenome]]
[[Category: Zhang H]]
[[Category: Zhang S]]