The enzyme converts the 3′-terminal phosphate of various RNA substrates into the 2′,3′-cyclic phosphodiester in an ATP-dependent reaction. Catalysis occurs by a three-step mechanism, starting with the activation of the enzyme by ATP, forming a phosphoramide bond between adenylate and a histidine residue [5,6]. The adenylate group is then transferred to the 3′-phosphate terminus of the substrate, forming the capped structure [RNA]-3′-(5′-diphosphoadenosine). Finally, the enzyme catalyses an attack of the vicinal O-2′ on the 3′-phosphorus, which results in formation of cyclic phosphate and release of the adenylate. The enzyme also has a polynucleotide 5′ adenylation activity [7].?cf. EC?6.5.1.5, RNA 3′-terminal-phosphate cyclase (GTP).
Cofactor
History
Reactions
Atp + (RNA)-3′-(3′-phospho-ribonucleoside) = amp + diphosphate + (RNA)- 3′-(2′,3′-cyclophospho)-ribonucleoside.
