title: Identification of a novel beta-replacement reaction in the biosynthesis of 2,3-diaminobutyric acid in peptidylnucleoside mureidomycin A.
abstract: 2,3-Diaminobutyric acid (DABA) is an unusual di-amino acid component of mureidomycin A, a member of the peptidylnucleoside antibiotic family produced by Streptomyces flavidovirens SANK 60486. Radiochemical assays using cell-free extract from S. flavidovirens revealed that 14C-L-Thr is converted into radiolabelled DABA by an ammonia-dependent beta-replacement activity, and not via oxidation to 3-keto-2-aminobutyric acid. The substrate specificity of partially purified enzyme was assayed using a spectrophotometric assay, and beta-replacement activity was inhibited by known inhibitors of PLP-dependent enzymes. These data imply that DABA is biosynthesised from L-Thr by a PLP-dependent beta-replacement enzyme, using ammonia as a nucleophile. These results are consistent with literature proposals for the biosynthesis of 2,3-diaminopropanoic acid from the viomycin biosynthetic gene cluster.
authors.affiliation: University of Warwick, Department of Chemistry, Coventry, United Kingdom.
authors.forename: Wai-Ho
authors.initials: WH
authors.lastname: Lam
authors.forename: Kathrin
authors.initials: K
authors.lastname: Rychli
authors.forename: Timothy D H
authors.initials: TD
authors.lastname: Bugg
mesh_terms: D020148:Butyric Acid / Q000737:chemistry*; D007700:Kinetics; D009705:Nucleosides / Q000096:biosynthesis / Q000138:chemical synthesis; D013302:Streptomyces / Q000378:metabolism
chemical_list: D009705:Nucleosides; D020148:Butyric Acid; C059803:mureidomycin A