Analysis of ThiC Variants in the Context of the Metabolic Network of Salmonella enterica

Abstract

ABSTRACT In bacteria, the 4-amino-hydroxymethyl-2-methylpyrimidine (HMP) moiety of thiamine is synthesized from 5-aminoimidazole ribotide (AIR), a branch point metabolite of purine and thiamine biosynthesis. ThiC is a member of the radical S -adenosylmethionine (AdoMet) superfamily and catalyzes the complex chemical rearrangement of AIR to HMP-P. As reconstituted in vitro , the ThiC reaction requires AdoMet, AIR, and reductant. This study analyzed variants of ThiC in vivo and in vitro to probe the metabolic network surrounding AIR in Salmonella enterica . Several variants of ThiC that required metabolic perturbations to function in vivo were biochemically characterized in vitro . Results presented herein indicate that the subtleties of the metabolic network have not been captured in the current reconstitution of the ThiC reaction.