Production of 8-Demethylgeldanamycin and 4,5-Epoxy-8-demethylgeldanamycin from a Recombinant Strain of <i>Streptomyces </i><i>h</i><i>ygroscopicus</i>

Abstract

Two new geldanamycin derivatives produced by genetic engineering of Streptomyces hygroscopicus strain K309-27-1 were isolated and characterized. Removal of the 8-methyl group of geldanamycin was achieved by replacing the AT4 domain of the polyketide synthase with a malonyl AT domain. The resulting strain produced 8-demethyl geldanamycin (2) and 4,5-epoxy-8-demethylgeldanamycin (3). The structures of both molecules were elucidated through interpretation of 1D and 2D NMR data as well as comparison with authentic geldanamycin derivatives. Compounds 2 and 3 displayed moderate cytotoxicity against the human breast cancer cell line SK-BR-3.