Structural highlights
Function
CSM6_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
- ↑ Niewoehner O, Jinek M. Structural basis for the endoribonuclease activity of the type III-A CRISPR-associated protein Csm6. RNA. 2016 Jan 13. PMID:26763118 doi:http://dx.doi.org/10.1261/rna.054098.115
- ↑ Kazlauskiene M, Kostiuk G, Venclovas C, Tamulaitis G, Siksnys V. A cyclic oligonucleotide signaling pathway in type III CRISPR-Cas systems. Science. 2017 Aug 11;357(6351):605-609. doi: 10.1126/science.aao0100. Epub 2017, Jun 29. PMID:28663439 doi:http://dx.doi.org/10.1126/science.aao0100
- ↑ Niewoehner O, Garcia-Doval C, Rostol JT, Berk C, Schwede F, Bigler L, Hall J, Marraffini LA, Jinek M. Type III CRISPR-Cas systems produce cyclic oligoadenylate second messengers. Nature. 2017 Aug 31;548(7669):543-548. doi: 10.1038/nature23467. Epub 2017 Jul, 19. PMID:28722012 doi:http://dx.doi.org/10.1038/nature23467
