Involved in biosynthesis of the thiamine precursor thiazole. Catalyzes the conversion of NAD and glycine to adenosine diphosphate 5-(2-hydroxyethyl)-4-methylthiazole-2-carboxylic acid (ADT), an adenylated thiazole intermediate. The reaction includes an iron-dependent sulfide transfer from a conserved cysteine residue of the protein to a thiazole intermediate. The enzyme can only undergo a single turnover, which suggests it is a suicide enzyme. May have additional roles in adaptation to various stress conditions and in DNA damage tolerance. [ADP-thiazole synthase]-L-cysteine + glycine + NAD(+) = [ADP-thiazole synthase]-dehydroalanine + ADP-5-ethyl-4-methylthiazole-2-carboxylate + 2 H(+) + 3 H2O + nicotinamide Binds 1 Fe cation per subunit. Homooctamer. Highest expression in developing embryos and green leaves and a very low level expression seen in endosperm, roots, etiolated shoots and immature ears. During embryo development, expression increases from 15-21 days after pollination and decreases slightly at day 24 and this level is maintained until day 36. During the catalytic reaction, a sulfide is transferred from Cys-219 to a reaction intermediate, generating a dehydroalanine residue. Belongs to the THI4 family.