Structural and mechanistic studies on ThiO, a glycine oxidase essential for thiamin biosynthesis in Bacillus subtilis.
Publication Type:Journal Article
Source:Biochemistry, Volume 42, Issue 10, p.2971-81 (2003)
Keywords:Amino Acid Oxidoreductases, Bacillus subtilis, Bacterial Proteins, Binding Sites, Crystallography, X-Ray, Deuterium, Flavin-Adenine Dinucleotide, Flavins, Flavoproteins, Kinetics, Mutation, Nuclear Magnetic Resonance, Biomolecular, Oxidation-Reduction, Protein Structure, Quaternary, Protein Structure, Tertiary, Stereoisomerism, Substrate Specificity, Thiamine, Thiazoles
<p>The thiO gene of Bacillus subtilis encodes an FAD-dependent glycine oxidase. This enzyme is a homotetramer with a monomer molecular mass of 42 kDa. In this paper, we demonstrate that ThiO is required for the biosynthesis of the thiazole moiety of thiamin pyrophosphate and describe the structure of the enzyme with N-acetylglycine bound at the active site. The closest structural relatives of ThiO are sarcosine oxidase and d-amino acid oxidase. The ThiO structure, as well as the observation that N-cyclopropylglycine is a good substrate, supports a hydride transfer mechanism for the enzyme. A mechanistic proposal for the role of ThiO in thiazole biosynthesis is also described.</p>