Engineered synthesis of 7-oxo- and 15-deoxy-15-oxo-amphotericins: insights into structure-activity relationships in polyene antibiotics.
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.
Power
Patrick
P
School of Biomolecular and Biomedical Science and Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.
Dunne
Terence
T
Murphy
Barry
B
Nic Lochlainn
Laura
L
Rai
Dilip
D
Borissow
Charles
C
Rawlings
Bernard
B
Caffrey
Patrick
P
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
D000935:Antifungal Agents; D011090:Polyenes; D048630:Polyketide Synthases; D000666:Amphotericin B; D010088:Oxidoreductases