Protein
CRISPR system single-strand-specific deoxyribonuclease Cas10/Csm1 (subtype III-A)
Organism
Streptococcus thermophilus
Function
When associated with the ternary Csm effector complex (the crRNA, Cas proteins and a cognate target ssRNA) synthesizes cyclic oligoadenylates (cOA) from ATP, producing cyclic triadenylate (cA3) up to cyclic hexaadenylate (cA6), which is the active cOA. The enzyme is also able to cyclize pppA3 up to pppA6. cOAs are second messengers that induce an antiviral state important for defense against invading nucleic acids. Synthesis of cOA can occur with AMP plus ATP, 2'dATP or 3'dATP (but no other nucleotides), and requires a free 3'-OH ribose moiety.
Similarity
Belongs to the CRISPR-associated Cas10/Csm1 family.
Sequence
MKKEKIDLFYGALLHDIGKVIQRATGERKKHALVGADWFDEIADNQVISDQIRYHMANYQSDKLGNDHLAYITYIADNIASGVDRRQSNEESDEDASAKIWDTYTNQADIFNVFGAQTDKRYFKPTVLNLKSKPNFASATYEPFSKGDYAAIATRIKNELAEFEFNQAQIDSLLNLFEAILSFVPSSTNSKEIADISLAEHSRLTAAFALAIYDYLEDKGRHNYKEDLFTKASAFYEEEAFLLASFDLSGIQDFIYNIATSGAAKQLKARSLYLDFMSEYIADSLLDKLGLNRANLLYVGGGHAYFVLANTEKTVETLVQFEKDFNQFLLANFQTRLYVAFGWGSFAAKDIMSELNSPESYRQIYQKASRMISEKKISRYDYRTLMLLNRGGKSSERECEICHSVENLVSYHDQKVCDICRGLYQFSKEIAHDHFIITENEGLPIGPNACLKGVAFEKLSQESFSRVYVKNDYKAGTIKATHVFVGDYQCDEIHKYAALSKNEDGLGIKRLAVVRLDVDDLGAAFMAGFSRQGNGQYSTLSRSATFSRSMSLFFKVYINQFASDKKLSIIYAGGDDVFAIGSWQDIIAFTVELRQNFIKWTNGKLTLSAGIGLFADKTPISLMAHQTGELEEAAKGNEKDSISLFSSDYTFKFDRFITNVYDDKLEQIRYFFNHQDERGKNFIYKLIELLRNYESEEKMNVARLAYYLTRLEELTDKDERDKFKQFKKLFFKWYTNNESDRKEAELALLLYVYEIRKD