CLONING AND SEQUENCE-ANALYSIS OF THE PUTATIVE RIFAMYCIN POLYKETIDE SYNTHASE GENE-CLUSTER FROM AMYCOLATOPSIS-MEDITERRANEI

The 54-kbp Type I polyketide synthase gene cluster, most probably invo lved in rifamycin biosynthesis by Amycolatopsis mediterranei, was clon ed in E. coli and completely sequenced. The DNA encodes five closely p acked, very large open reading frames reading in one direction. As exp ected from the chemical structure of rifamycins, ten polyketide syntha se modules and a CoA ligase domain were identified in the five open re ading frames which contain one to three polyketide synthase modules ea ch. The order of the functional domains on the DNA probably reflects t he order in which they are used because each of the modules contains t he predicted acetate or propionate transferase, dehydratase, and beta- ketoacyl-ACP reductase functions, required for the respective step in rifamycin biosynthesis. (C) 1998 Federation of European Microbiologica l Societies. Published by Elsevier Science B.V.