title: Structural insights into the function of the thiamin biosynthetic enzyme Thi4 from Saccharomyces cerevisiae.
abstract: The structure of thiazole synthase (Thi4) from Saccharomyces cerevisiae was determined to 1.8 A resolution. Thi4 exists as an octamer with two monomers in the asymmetric unit. The structure reveals the presence of a tightly bound adenosine diphospho-5-(beta-ethyl)-4-methylthiazole-2-carboxylic acid at the active site. The isolation of this reaction product identifies NAD as the most likely precursor and provides the first mechanistic insights into the biosynthesis of the thiamin thiazole in eukaryotes. Additionally, the Thi4 structure reveals the first protein structure with a GR(2) domain that binds NAD instead of FAD, raising interesting questions about how this protein evolved from a flavoenzyme to a NAD binding enzyme.
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, USA.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Jurgenson
authors.forename: Abhishek
authors.initials: A
authors.lastname: Chatterjee
authors.forename: Tadhg P
authors.initials: TP
authors.lastname: Begley
authors.forename: Steven E
authors.initials: SE
authors.lastname: Ealick
mesh_terms: D000595:Amino Acid Sequence; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism*; D013831:Thiamine / Q000096:biosynthesis* / Q000737:chemistry
chemical_list: D029701:Saccharomyces cerevisiae Proteins; C089358:THI4 protein, S cerevisiae; D009243:NAD; D005182:Flavin-Adenine Dinucleotide; D013831:Thiamine