EC - PreQ1 synthase

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IntEnz Enzyme Nomenclature


Accepted name:
preQ1 synthase
Other names:
preQ0 reductase
preQ0 oxidoreductase
7-cyano-7-deazaguanine reductase
queuine:NADP+ oxidoreductase (incorrect as queuine is not the product)
queuine synthase (incorrect as queuine is not the product)
Systematic name:
7-aminomethyl-7-carbaguanine:NADP+ oxidoreductase



The reaction occurs in the reverse direction. This enzyme catalyses one of the early steps in the synthesis of queosine (Q-tRNA), and is followed by the action of EC, queuine tRNA-ribosyltransferase. Queosine 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

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0033739
CAS Registry Number: 1256460-80-6
UniProtKB/Swiss-Prot: (417) [show] [UniProt]


  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: 4264-4269 (2005). [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: 107-109 (1979). [PMID: 388227]
  3. Kuchino, Y., Kasai, H., Nihei, K., Nishimura, S.
    Biosynthesis of the modified nucleoside Q in transfer RNA.
    Nucleic Acids Res. 3: 393-398 (1976). [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: 2289-2296 (1978). [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: 4215-4223 (1978). [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 Crystallograph. Sect. F Struct. Biol. Cryst. Commun. 61: 945-948 (2005). [PMID: 16511203]

[EC created 2006]