title: Identification of a gene cluster for antibacterial polyketide-derived antibiotic biosynthesis in the nystatin producer Streptomyces noursei ATCC 11455.
abstract: Streptomyces noursei ATCC 11455 produces the antifungal polyene antibiotic nystatin containing the deoxysugar moiety mycosamine. Part of the deoxythymidyl diphosphate (TDP)-glucose dehydratase gene (gdhA) known to be involved in deoxysugar biosynthesis was amplified by PCR from genomic DNA of S. noursei ATCC 11455. A gene library for S. noursei was made and screened with the gdhA probe. Several overlapping phage clones covering about 30 kb of the S. noursei genome were physically mapped. A partial DNA sequencing analysis of this region resulted in the identification of several putative genes typical of macrolide antibiotic biosynthetic gene clusters. A gene-transfer system for 5. noursei has been established, and gene deletion or disruption experiments within the putative biosynthetic gene cluster were performed. All of the knock-out mutants retained the ability to produce nystatin, suggesting that the identified gene cluster is not involved in biosynthesis of this antibiotic. Culture extracts from the wild-type strain and three knock-out mutants were analysed by TLC followed by a bioassay against Micrococcus luteus. Two antibacterial compounds were found to be synthesized by the wild-type strain while only one was produced by the mutants. This provided evidence for the involvement of the identified gene cluster in the biosynthesis of a presumably novel antibacterial macrolide antibiotic in S. noursei.
authors.affiliation: UNIGEN Center for Molecular Biology and Department of Biotechnology, NTNU,N-7489 Trondheim, Norway1.
authors.forename: Sergey
authors.initials: S
authors.lastname: Zotchev
authors.affiliation: Nord-Trondelag College, Dept of Engineering,N-7600 Levanger, Norway2.
authors.forename: Kare
authors.initials: K
authors.lastname: Haugan
authors.affiliation: UNIGEN Center for Molecular Biology and Department of Biotechnology, NTNU,N-7489 Trondheim, Norway1.
authors.forename: Olga
authors.initials: O
authors.lastname: Sekurova
authors.affiliation: SINTEF Applied Chemistry, SINTEF, N-7034 Trondheim, Norway3.
authors.forename: Havard
authors.initials: H
authors.lastname: Sletta
authors.affiliation: SINTEF Applied Chemistry, SINTEF, N-7034 Trondheim, Norway3.
authors.forename: Trond E
authors.initials: TE
authors.lastname: Ellingsen
authors.affiliation: UNIGEN Center for Molecular Biology and Department of Biotechnology, NTNU,N-7489 Trondheim, Norway1.
authors.forename: Svein
authors.initials: S
authors.lastname: Valla
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D017353:Gene Deletion; D018014:Gene Transfer Techniques; D005798:Genes, Bacterial; D006836:Hydro-Lyases; D008969:Molecular Sequence Data; D005810:Multigene Family; D009761:Nystatin / Q000096:biosynthesis*; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D013302:Streptomyces / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D009761:Nystatin; D006836:Hydro-Lyases; C022771:dTDPglucose 4,6-dehydratase