Thiamine biosynthesis in Escherichia coli: Identification of the intermediate and by-product derived from tyrosine

In anaerobic organisms such as E. coli the tyrosine lyase ThiH is essential for the biosynthesis of the thiazole moiety of the vitamin thiamine. ThiH is a member of the radical AdoMet family. The products formed by cleavage of tyrosine in vitro have been identified and suggest a radical-mediated cleavage resulting in p-cresol and dehydroglycine which is hydrolyzed to glyoxylate.