ExplorEnz: EC 6.5.1.4

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6.5.1.4

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]-N^τ-(5′-adenylyl)-L-histidine + diphosphate
(1b) [RNA 3′-phosphate cyclase]-N^τ-(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 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′ adenylylation activity [7]. cf. EC 6.5.1.5, RNA 3′-terminal-phosphate cyclase (GTP).

Links to other databases:

BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 85638-41-1

References:

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. [DOI] [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. [DOI] [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. [DOI] [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. [DOI] [PMID: 10574971]
6.	Tanaka, N. and Shuman, S. Structure-activity relationships in human RNA 3′-phosphate cyclase. RNA 15 (2009) 1865–1874. [DOI] [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. [DOI] [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. [DOI] [PMID: 23945037]

[EC 6.5.1.4 created 1986, modified 1989, modified 2013, modified 2016]