The Enzyme Database

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Accepted name: preQ1 synthase
Reaction: 7-aminomethyl-7-carbaguanine + 2 NADP+ = 7-cyano-7-carbaguanine + 2 NADPH + 2 H+
For diagram of queuine biosynthesis, click here
Glossary: 7-aminomethyl-7-carbaguanine = preQ1 = 7-aminomethyl-7-deazaguanine
7-cyano-7-carbaguanine = preQ0 = 7-cyano-7-deazaguanine
Other name(s): YkvM; QueF; preQ0 reductase; preQ0 oxidoreductase; 7-cyano-7-deazaguanine reductase; queuine synthase (incorrect as queuine is not the product); queuine:NADP+ oxidoreductase (incorrect as queuine is not the product)
Systematic name: 7-aminomethyl-7-carbaguanine:NADP+ oxidoreductase
Comments: The reaction occurs in the reverse direction. This enzyme catalyses one of the early steps in the synthesis of queuosine (Q-tRNA), and is followed by the action of EC, queuine tRNA-ribosyltransferase. Queuosine is found in the wobble position of tRNAGUN in Eukarya and Bacteria [2] and is thought to be involved in translational modulation. The enzyme is not a GTP cyclohydrolase, as was thought previously based on sequence-homology studies.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 1256460-80-6
1.  Van Lanen, S.G., Reader, J.S., Swairjo, M.A., de Crécy-Lagard, V., Lee, B. and Iwata-Reuyl, D. From cyclohydrolase to oxidoreductase: discovery of nitrile reductase activity in a common fold. Proc. Natl. Acad. Sci. USA 102 (2005) 4264–4269. [PMID: 15767583]
2.  Yokoyama, S., Miyazawa, T., Iitaka, Y., Yamaizumi, Z., Kasai, H. and Nishimura, S. Three-dimensional structure of hyper-modified nucleoside Q located in the wobbling position of tRNA. Nature 282 (1979) 107–109. [PMID: 388227]
3.  Kuchino, Y., Kasai, H., Nihei, K. and Nishimura, S. Biosynthesis of the modified nucleoside Q in transfer RNA. Nucleic Acids Res. 3 (1976) 393–398. [PMID: 1257053]
4.  Okada, N., Noguchi, S., Nishimura, S., Ohgi, T., Goto, T., Crain, P.F. and McCloskey, J.A. Structure determination of a nucleoside Q precursor isolated from E. coli tRNA: 7-(aminomethyl)-7-deazaguanosine. Nucleic Acids Res. 5 (1978) 2289–2296. [PMID: 353740]
5.  Noguchi, S., Yamaizumi, Z., Ohgi, T., Goto, T., Nishimura, Y., Hirota, Y. and Nishimura, S. Isolation of Q nucleoside precursor present in tRNA of an E. coli mutant and its characterization as 7-(cyano)-7-deazaguanosine. Nucleic Acids Res. 5 (1978) 4215–4223. [PMID: 364423]
6.  Swairjo, M.A., Reddy, R.R., Lee, B., Van Lanen, S.G., Brown, S., de Crécy-Lagard, V., Iwata-Reuyl, D. and Schimmel, P. Crystallization and preliminary X-ray characterization of the nitrile reductase QueF: a queuosine-biosynthesis enzyme. Acta Crystallogr. F Struct. Biol. Cryst. Commun. 61 (2005) 945–948. [PMID: 16511203]
[EC created 2006]

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