title: Engineered synthesis of 7-oxo- and 15-deoxy-15-oxo-amphotericins: insights into structure-activity relationships in polyene antibiotics.
abstract: Site-directed mutagenesis and gene replacement were used to inactivate two ketoreductase (KR) domains within the amphotericin polyketide synthase in Streptomyces nodosus. The KR12 domain was inactivated in the DeltaamphNM strain, which produces 16-descarboxyl-16-methyl-amphotericins. The resulting mutant produced low levels of the expected 15-deoxy-15-oxo analogs that retained antifungal activity. These compounds can be useful for further chemical modification. Inactivation of the KR16 domain in the wild-type strain led to production of 7-oxo-amphotericin A and 7-oxo-amphotericin B in good yield. 7-oxo-amphotericin B was isolated, purified, and characterized as the N-acetyl methyl ester derivative. 7-oxo-amphotericin B had good antifungal activity and was less hemolytic than amphotericin B. These results indicate that modification at the C-7 position can improve the therapeutic index of amphotericin B.
authors.affiliation: School of Biomolecular and Biomedical Science and Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Patrick
authors.initials: P
authors.lastname: Power
authors.forename: Terence
authors.initials: T
authors.lastname: Dunne
authors.forename: Barry
authors.initials: B
authors.lastname: Murphy
authors.forename: Laura
authors.initials: L
authors.lastname: Nic Lochlainn
authors.forename: Dilip
authors.initials: D
authors.lastname: Rai
authors.forename: Charles
authors.initials: C
authors.lastname: Borissow
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 / Q000494:pharmacology*; D000935:Antifungal Agents / Q000096:biosynthesis / Q000737:chemistry / Q000494:pharmacology*; D008956:Models, Chemical; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011090:Polyenes / Q000737:chemistry / Q000494:pharmacology*; D048630:Polyketide Synthases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015202:Protein Engineering / Q000379:methods*; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics; D013329:Structure-Activity Relationship
chemical_list: D000935:Antifungal Agents; D011090:Polyenes; D048630:Polyketide Synthases; D000666:Amphotericin B; D010088:Oxidoreductases