EC - RNA 3'-terminal-phosphate cyclase (GTP)

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IntEnz Enzyme Nomenclature


Accepted name:
RNA 3'-terminal-phosphate cyclase (GTP)
Other names:
RNA-3'-phosphate cyclase (GTP)
Systematic name:
RNA-3'-phosphate:RNA ligase (cyclizing, GMP-forming)



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

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB


  1. Sato, A., Soga, T., Igarashi, K., Takesue, K., Tomita, M., Kanai, A.
    GTP-dependent RNA 3'-terminal phosphate cyclase from the hyperthermophilic archaeon Pyrococcus furiosus.
    Genes Cells 16 : 1190-1199 (2011). [PMID: 22074260]

[EC created 2013, modified 2016]