The Enzyme Database

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Accepted name: RNA 3′-terminal-phosphate cyclase (GTP)
Reaction: GTP + [RNA]-3′-(3′-phospho-ribonucleoside) = GMP + diphosphate + [RNA]-3′-(2′,3′-cyclophospho)-ribonucleoside (overall reaction)
(1a) GTP + [RNA 3′-phosphate cyclase]-L-histidine = 5′-guanosyl [RNA 3′-phosphate cyclase]-Nτ-phosphono-L-histidine + diphosphate
(1b) 5′-guanosyl [RNA 3′-phosphate cyclase]-Nτ-phosphono-L-histidine + [RNA]-3′-(3′-phospho-ribonucleoside) = [RNA 3′-phosphate cyclase]-L-histidine + [RNA]-3′-ribonucleoside-3′-(5′-diphosphoguanosine)
(1c) [RNA]-3′-ribonucleoside-3′-(5′-diphosphoguanosine) = [RNA]-3′-(2′,3′-cyclophospho)-ribonucleoside + GMP
Other name(s): Pf-Rtc; RNA-3′-phosphate cyclase (GTP)
Systematic name: RNA-3′-phosphate:RNA ligase (cyclizing, GMP-forming)
Comments: The enzyme, which is specific for GTP, was characterized from the archaeon Pyrococcus furiosus. The enzyme converts the 3′-terminal phosphate of various RNA substrates into the 2′,3′-cyclic phosphodiester in a GTP-dependent reaction. Catalysis occurs by a three-step mechanism, starting with the activation of the enzyme by GTP, forming a phosphoramide bond between guanylate and a histidine residue. The guanylate group is then transferred to the 3′-phosphate terminus of the substrate, forming the capped structure [RNA]-3′-(5′-diphosphoguanosine). 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 guanylate. cf. EC, RNA-3′-phosphate cyclase (ATP).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
1.  Sato, A., Soga, T., Igarashi, K., Takesue, K., Tomita, M. and Kanai, A. GTP-dependent RNA 3′-terminal phosphate cyclase from the hyperthermophilic archaeon Pyrococcus furiosus. Genes Cells 16 (2011) 1190–1199. [DOI] [PMID: 22074260]
[EC created 2013, modified 2016]

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