title: Biosynthesis of the unusual 5,5-gem-dimethyl-deoxysugar noviose: investigation of the C-methyltransferase gene cloU.
abstract: The aminocoumarin antibiotic clorobiocin contains an unusual branched deoxysugar with a 5,5-gem-dimethyl structure. Inactivation of the putative C-methyltransferase gene cloU was carried out, which led to the loss of the axial methyl group at C-5 of this deoxysugar moiety. This result establishes the function of cloU, and at the same time it proves that the biosynthesis of the deoxysugar moiety of clorobiocin proceeds via a 3,5-epimerization of the dTDP-4-keto-6-deoxyglucose intermediate. The inactivation was carried out on a cosmid which contained the entire clorobiocin biosynthetic gene cluster. Expression of the modified cluster in a heterologous host led to the formation of desmethyl-clorobiocin and a structural isomer thereof. Both compounds were isolated on a preparative scale, their structures were elucidated by 1H-NMR and mass spectroscopy and their antibacterial activity was assayed.
authors.affiliation: Pharmazeutische Biologie, Pharmazeutisches Institut, Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Freitag
authors.affiliation: Pharmazeutische Biologie, Pharmazeutisches Institut, Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany.
authors.forename: Shu-Ming
authors.initials: SM
authors.lastname: Li
authors.affiliation: Pharmazeutische Biologie, Pharmazeutisches Institut, Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany.
authors.forename: Lutz
authors.initials: L
authors.lastname: Heide
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D008780:Methyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000096:biosynthesis*; D009675:Novobiocin / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry / Q000494:pharmacology; D013302:Streptomyces / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D009005:Monosaccharides; C494073:noviose; D009675:Novobiocin; C006260:clorobiocin; D008780:Methyltransferases