| EC |
4.1.99.23 |
| Accepted name: |
5-hydroxybenzimidazole synthase |
| Reaction: |
5-amino-1-(5-phospho-β-D-ribosyl)imidazole + S-adenosyl-L-methionine + reduced acceptor = 5-hydroxybenzimidazole + 5′-deoxyadenosine + L-methionine + formate + NH3 + phosphate + oxidized acceptor |
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For diagram of 5-hydroxybenzimidazole biosynthesis, click here |
| Other name(s): |
bzaF (gene name); HBI synthase |
| Systematic name: |
5-amino-1-(5-phospho-β-D-ribosyl)imidazole formate-lyase (5-hydroxybenzimidazole-forming) |
| Comments: |
The enzyme, purified from bacteria, is part of the anaerobic pathway for cobalamin biosynthesis. It binds a [4Fe-4S] cluster that is coordinated by 3 cysteines and an exchangeable S-adenosyl-L-methionine molecule. The first stage of catalysis is reduction of the S-adenosyl-L-methionine to produce L-methionine and a 5′-deoxyadenosin-5′-yl radical that is crucial for the conversion of the substrate. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc |
| References: |
| 1. |
Mehta, A.P., Abdelwahed, S.H., Fenwick, M.K., Hazra, A.B., Taga, M.E., Zhang, Y., Ealick, S.E. and Begley, T.P. Anaerobic 5-hydroxybenzimidazole formation from aminoimidazole ribotide: an unanticipated intersection of thiamin and vitamin B12 biosynthesis. J. Am. Chem. Soc. 137 (2015) 10444–10447. [DOI] [PMID: 26237670] |
| 2. |
Hazra, A.B., Han, A.W., Mehta, A.P., Mok, K.C., Osadchiy, V., Begley, T.P. and Taga, M.E. Anaerobic biosynthesis of the lower ligand of vitamin B12. Proc. Natl. Acad. Sci. USA 112 (2015) 10792–10797. [DOI] [PMID: 26246619] |
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| [EC 4.1.99.23 created 2017] |
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