title: The structural and mutational analyses of O-ureido-L-serine synthase necessary for D-cycloserine biosynthesis.
abstract: We have recently been successful in cloning a gene cluster necessary for the biosynthesis of D-cycloserine (D-CS) from D-CS-producing Streptomyces lavendulae ATCC11924. Although dcsD, one of the ORFs located on the gene cluster, encodes a protein homologous to O-acetylserine sulfhydrylase that synthesizes L-cysteine using O-acetyl-L-serine together with sulfide, it functions to form O-ureido-L-serine as a D-CS biosynthetic intermediate, using O-acetyl-L-serine together with hydroxyurea (HU). In the present study, using crystallographic and mutational studies, three amino acid residues in DcsD that are important for the substrate preference toward HU were determined. We showed that two of the three residues are important for the binding of HU into the substrate-binding pocket. The other residue contributes to the formation of a loose hydrogen-bond network during the catalytic reaction. Information regarding the amino acid residues will be very useful in the design of a new catalyst for synthesizing the β-substituted-L-alanine derivatives.
  
  
  METHODS
  The atomic coordinates and structure factors of wild-type DcsD and l-OUS-bound K43A mutant of DcsD have been deposited in the Protein Data Bank under accession codes 3X43 and 3X44, respectively.
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan.
authors.forename: Narutoshi
authors.initials: N
authors.lastname: Uda
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Matoba
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Oda
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Kumagai
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Sugiyama
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D055162:Biocatalysis; D020134:Catalytic Domain; D017124:Conserved Sequence; D003523:Cycloserine / Q000378:metabolism; D003547:Cysteine Synthase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D006860:Hydrogen Bonding; D006918:Hydroxyurea / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D012694:Serine / Q000031:analogs & derivatives* / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D050505:Mutant Proteins; D011994:Recombinant Proteins; D012694:Serine; D003523:Cycloserine; D003547:Cysteine Synthase; C043943:O-acetylserine; D006918:Hydroxyurea
keywords: Streptomyces lavendulae; antibiotic; biosynthesis; crystal structure; d-cycloserine