CRISPR system ring nuclease SSO2081

UniProtKB accession:  Q7LYJ6

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UniProtKB description:  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). A nuclease that degrades cyclic oligoadenylates (cOA), second messengers that induce an antiviral state important for defense against invading nucleic acids. Destruction of cOA deactivates the Csx1 ribonuclease, preventing uncontrolled degradation of cellular RNA. Degrades cA4 (a tetraadenylate ring) into a linear diadenylate product with 5'-OH and 2',3'-cyclic phosphate termini. Is 10-fold more active than SSO1393, suggesting this is the major cA4 degradation enzyme. Is highly specific for cA4; it has very poor activity on cA6 and no discernible activity against a number of cyclic dinucletides. There may be 2 active sites per homodimer (PubMed:30232454).