title: Biosynthesis of deoxyamphotericins and deoxyamphoteronolides by engineered strains of Streptomyces nodosus.
abstract: Amphotericin B is an antifungal antibiotic produced by Streptomyces nodosus. During biosynthesis of amphotericin, the macrolactone core undergoes three modifications: oxidation of a methyl branch to a carboxyl group, mycosaminylation, and hydroxylation. Gene disruption was undertaken to block two of these modifications. Initial experiments targeted the amphDIII gene, which encodes a GDP-D-mannose 4,6-dehydratase involved in biosynthesis of mycosamine. Analysis of products by mass spectrometry and NMR indicated that the amphDIII mutant produced 8-deoxyamphoteronolides A and B. This suggests that glycosylation with mycosamine normally precedes C-8 hydroxylation and that formation of the exocyclic carboxyl group can occur prior to both these modifications. Inactivation of the amphL cytochrome P450 gene led to production of novel polyenes with masses appropriate for 8-deoxyamphotericins A and B. These compounds retained antifungal activity and may be useful new antibiotics.
authors.affiliation: Department of Industrial Microbiology, Centre for Synthesis and Chemical Biology, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland.
authors.forename: Barry
authors.initials: B
authors.lastname: Byrne
authors.forename: Maria
authors.initials: M
authors.lastname: Carmody
authors.forename: Emma
authors.initials: E
authors.lastname: Gibson
authors.forename: Bernard
authors.initials: B
authors.lastname: Rawlings
authors.forename: Patrick
authors.initials: P
authors.lastname: Caffrey
mesh_terms: D000666:Amphotericin B / Q000031:analogs & derivatives* / Q000096:biosynthesis* / Q000737:chemistry; D000935:Antifungal Agents / Q000737:chemistry / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D005818:Genetic Engineering; D006031:Glycosylation; D006900:Hydroxylation; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D009154:Mutation / Q000235:genetics; D011090:Polyenes / Q000737:chemistry; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000935:Antifungal Agents; D011090:Polyenes; C058220:amphoteronolide B; D000666:Amphotericin B