Structural insights into the function of the thiamin biosynthetic enzyme Thi4 from Saccharomyces cerevisiae

The structure of thiole synthase (Thi4) from Saccharomyces cerevisiae was determined to 1.8 angstrom resolution. Thi4 exists as an octamer with two monomers in the asymmetric unit and reveals the presence of a tightly bound adenosine diphospho-5-[(beta)-ethyl)]-4-methylthiazole-2-carboxylic acid at the active site and also the first protein structure with a GR2 domain that binds NAD instead of FAD.