Reaction: 7-aminomethyl-7-carbaguanine + 2 NADP+ = 7-cyano-7-carbaguanine + 2 NADPH
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
Systematic name: 7-aminomethyl-7-carbaguanine:NADP+ oxidoreductase
Comments: The reaction occurs in the reverse direction. This enzyme catalyses one of the later steps in the synthesis of queosine (Q-tRNA), following on from the action of EC 126.96.36.199, tRNA-guanosine34 transglycosylase. Queuosine is found in the wobble position of tRNAGUN in Eukarya and Bacteria  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 Cr̩cy-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. Crystal. Co 61 (2005) 945-948.