6o7i

Cryo-EM structure of Csm-crRNA-target RNA ternary bigger complex in complex with cA4 in type III-A CRISPR-Cas system

Loading... Status: waiting for Mol* initialization Structural highlights 6o7i is a 11 chain structure with sequence from Thermococcus onnurineus, Thermococcus onnurineus NA1 and Synthetic construct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.2Å Ligands: ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function 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. 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]

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