IUBMB Enzyme Nomenclature


Accepted name: RNA 3'-terminal-phosphate cyclase (ATP)

Reaction: ATP + [RNA]-3'-(3'-phospho-ribonucleoside) = AMP + diphosphate + [RNA]-3'-(2',3'-cyclophospho)-ribonucleoside (overall reaction)
(1a) ATP + [RNA 3'-phosphate cyclase]-L-histidine = [RNA 3'-phosphate cyclase]-Nτ-(5'-adenylyl)-L-histidine + diphosphate
(1b) [RNA 3'-phosphate cyclase]-Nτ-(5'-adenylyl)-L-histidine + [RNA]-3'-(3'-phospho-ribonucleoside) = [RNA 3'-phosphate cyclase]-L-histidine + [RNA]-3'-ribonucleoside-3'-(5'-diphosphoadenosine)
(1c) [RNA]-3'-ribonucleoside-3'-(5'-diphosphoadenosine) = [RNA]-3'-(2',3'-cyclophospho)-ribonucleoside + AMP

Other name(s): rtcA (gene name); RNA cyclase (ambiguous); RNA-3'-phosphate cyclase (ambiguous)

Systematic name: RNA-3'-phosphate:RNA ligase (cyclizing, AMP-forming)

Comments: 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 O2' on the 3'-phosphorus, which results in formation of cyclic phosphate and release of the adenylate. The enzyme also has a polynucleotide 5' adenylylation activity [7]. cf. EC, RNA 3'-terminal-phosphate cyclase (GTP).

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 85638-41-1


1. Filipowicz, W., Konarska, M., Gross, H.J. and Shatkin, A.J. RNA 3'-terminal phosphate cyclase activity and RNA ligation in HeLa cell extract. Nucleic Acids Res. 11 (1983) 1405-1418. [PMID: 6828385]

2. Reinberg, D., Arenas, J. and Hurwitz, J. The enzymatic conversion of 3'-phosphate terminated RNA chains to 2',3'-cyclic phosphate derivatives. J. Biol. Chem. 260 (1985) 6088-6097. [PMID: 2581947]

3. Genschik, P., Billy, E., Swianiewicz, M. and Filipowicz, W. The human RNA 3'-terminal phosphate cyclase is a member of a new family of proteins conserved in Eucarya, Bacteria and Archaea. EMBO J. 16 (1997) 2955-2967. [PMID: 9184239]

4. Genschik, P., Drabikowski, K. and Filipowicz, W. Characterization of the Escherichia coli RNA 3'-terminal phosphate cyclase and its σ54-regulated operon. J. Biol. Chem. 273 (1998) 25516-25526. [PMID: 9738023]

5. Billy, E., Hess, D., Hofsteenge, J. and Filipowicz, W. Characterization of the adenylation site in the RNA 3'-terminal phosphate cyclase from Escherichia coli. J. Biol. Chem. 274 (1999) 34955-34960. [PMID: 10574971]

6. Tanaka, N. and Shuman, S. Structure-activity relationships in human RNA 3'-phosphate cyclase. RNA 15 (2009) 1865-1874. [PMID: 19690099]

7. Chakravarty, A.K. and Shuman, S. RNA 3'-phosphate cyclase (RtcA) catalyzes ligase-like adenylylation of DNA and RNA 5'-monophosphate ends. J. Biol. Chem. 286 (2011) 4117-4122. [PMID: 21098490]

8. Das, U. and Shuman, S. 2'-Phosphate cyclase activity of RtcA: a potential rationale for the operon organization of RtcA with an RNA repair ligase RtcB in Escherichia coli and other bacterial taxa. RNA 19 (2013) 1355-1362. [PMID: 23945037]

[EC created 1986, modified 1989, modified 2013, modified 2016]

Return to EC 6.5.1 home page
Return to EC 6.5 home page
Return to EC 6 home page
Return to Enzymes home page
Return to IUBMB Biochemical Nomenclature home page