Summary

ThiS is the sulfur source for the thiazole moiety in thiamin biosynthesis. In a reaction catalyzed by the ThiF protein, the carboxy-terminal glycine of ThiS is adenylated. Sulfur is then transferred from a [ThiI sulfur-carrier protein]-S-sulfanyl-L-cysteine, forming a thiocarboxylate, in a reaction catalyzed by ThiF and the ThiI protein [Begley99, Taylor98a].

The thiocarboxylate form of ThiS is one of the substrates used by thiazole synthase.