FIG. 1.

Biosynthetic pathways for thiamine and GSH. (A) Our current understanding of thiamine biosynthesis in S. enterica. Enzymes for each of the reactions are indicated above the relevant arrows. Enzymes that have not been demonstrated but are predicted to function at certain steps in thiamine biosynthesis are in parentheses. The nitrogen and carbon atoms donated by tyrosine are boxed in the THZ structure. The position of ThiH with respect to ThiG, -F, and -S is based partially on work reported here. (B) The GSH biosynthetic pathway. Abbreviations: PRPP, phosphoribosylpyrophosphate; Gln, glutamine; AIR, 5-aminoimidazole ribotide; THZ-P, 4-methyl-5-β-hydroxyethyl-thiazole monophosphate; HMP-PP, 4-amino-5-hydroxymethyl-2-methylpyrimidine pyrophosphate; TMP, thiamine monophosphate; TPP, thiamine pyrophosphate.