Steve Ealick's Research Group


Abstract:

Mehta AP, Abdelwahed SH, Fenwick MK, Hazra AB, Taga ME, Zhang Y, Ealick SE, and Begley TP. Anaerobic 5-Hydroxybenzimidazole formation from aminoimidazole ribotide: an unanticipated intersection of thiamin and vitamin B12 biosynthesis. J. Am. Chem. Soc. 137:10444−10447 (2015).

Comparative genomics of the bacterial thiamin pyrimidine synthase (thiC) revealed a paralog of thiC (thiC-1) clustered with anaerobic vitamin B12 biosynthetic genes. Here we demonstrate that ThiC-1 is a radical S-adenosylmethionine enzyme that catalyzes the remarkable conversion of aminoimidazole ribotide (AIR) to 5-hydroxybenzimidazole (5-HBI). We identify the origin of key product atoms and propose a reaction mechanism. These studies represent the first step in solving a long-standing problem in anaerobic vitamin B12 assembly and reveal an unanticipated intersection of thiamin and vitamin B12 biosynthesis.

 

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