View source for 6mur


==Cryo-EM structure of Csm-crRNA-target RNA ternary complex in type III-A CRISPR-Cas system==
<SX load='6mur' size='340' side='right' viewer='molstar' caption='[[6mur]], [[Resolution|resolution]] 3.10&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6mur]] is a 8 chain structure with sequence from [https://en.wikipedia.org/wiki/Thermococcus_onnurineus Thermococcus onnurineus] and [https://en.wikipedia.org/wiki/Thermococcus_onnurineus_NA1 Thermococcus onnurineus NA1]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6MUR OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6MUR 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=6mur FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6mur OCA], [https://pdbe.org/6mur PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6mur RCSB], [https://www.ebi.ac.uk/pdbsum/6mur PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6mur ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CAS10_THEON CAS10_THEON] 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). The type III-A Csm effector complex binds crRNA and acts as a crRNA-guided RNase, DNase and cyclic oligoadenylate synthase; binding of target RNA cognate to the crRNA is required for all activities.[UniProtKB:A0A0A7HFE1]  A single-strand deoxyribonuclease (ssDNase) which digests linear and circular ssDNA; has 5'-3' and 3'-5' exonuclease activity as well as a less efficient endonuclease activity. Has a minimal size requirement; 100 nucleotide ssDNA (nt) is more efficiently digested than 50 or 25 nt ssDNA, while 14 nt ssDNA is not cleaved at all. It has no activity on dsDNA or ssRNA.<ref>PMID:25773141</ref>   ssDNase activity is stimulated in the ternary Csm effector complex; binding of cognate target RNA activates the ssDNase, as the target RNA is degraded ssDNA activity decreases.[UniProtKB:A0A0A7HFE1]  When associated with the ternary Csm effector complex (the crRNA, Cas proteins and a cognate target ssRNA) synthesizes cyclic oligoadenylates (cOA) from ATP. cOAs are second messengers that stimulate the ssRNase activity of Csm6, inducing an antiviral state important for defense against invading nucleic acids.[UniProtKB:A0A0A7HFE1]
== References ==
<references/>
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[[Category: Large Structures]]
[[Category: Thermococcus onnurineus]]
[[Category: Thermococcus onnurineus NA1]]
[[Category: Eng ET]]
[[Category: Jia N]]
[[Category: Patel DJ]]
[[Category: Wang C]]