Reaction: aurachin B + NAD+ + H2O = 4-[(2E,6E)-farnesyl]-4-hydroxy-2-methyl-3-oxo-3,4-dihydroquinoline 1-oxide + NADH + H+ (overall reaction)
(1a) 4-[(2E,6E)-farnesyl]-3,4-dihydroxy-2-methyl-3,4-dihydroquinoline 1-oxide + NAD+ = 4-[(2E,6E)-farnesyl]-4-hydroxy-2-methyl-3-oxo-3,4-dihydroquinoline 1-oxide + NADH + H+
(1b) aurachin B + H2O = 4-[(2E,6E)-farnesyl]-3,4-dihydroxy-2-methyl-3,4-dihydroquinoline 1-oxide (spontaneous)
Glossary: aurachin B= 4-[(2E,6E,10E)-3,7-dimethyldodeca-2,6,10-trien-1-yl]-3-hydroxy-2-methylquinoline 1-oxide
Other name(s): AuaH
Systematic name: aurachin B:NAD+ 3-oxidoreductase
Comments: The enzyme from the bacterium Stigmatella aurantiaca catalyses the final step in the conversion of aurachin C to aurachin B. In vivo the enzyme catalyses the reduction of 4-[(2E,6E)-farnesyl]-4-hydroxy-2-methyl-3-oxo-3,4-dihydroquinoline-1-oxide to form 4-[(2E,6E)-farnesyl]-2-methyl-1-oxo-3,4-dihydroquinoline-3,4-diol (note that the reactions written above proceed from right to left), which then undergoes a spontaneous dehydration to form aurachin B.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Katsuyama, Y., Harmrolfs, K., Pistorius, D., Li, Y. and Muller, R. A semipinacol rearrangement directed by an enzymatic system featuring dual-function FAD-dependent monooxygenase. Angew Chem. Int. Ed. Engl. 51 (2012) 9437-9440. [PMID: 22907798]