8jh1
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Crystal Structure of the Csm6 Y161A mutant from Thermus thermophilus HB8 in complex with cyclic-tetraadenylate (cA4)
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Structural highlights
FunctionCSM6_THET8 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). 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. This protein is not part of the Csm effector complex (Probable). A single-strand-specific endoribonuclease (ssRNase) producing free 5'-OH (PubMed:26763118). Activity is approximately 1000-fold stimulated by cyclic oligoadenylate (cOA); only cyclic tetraadenylate (cA4) stimulates the ssRNase activity while linear oligoadenylates do not activate the RNase (PubMed:28663439). Another study showed stimulation by linear tetraadenylate at very high concentrations, but did not examine stimulation by cA4 (PubMed:28722012).[1] [2] [3] References
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This page was last modified 11:45, 13 December 2023.