SELF CLONING IN MICROMONOSPORA-OLIVASTEROSPORA OF FMS GENES FOR FORTIMICIN-A (ASTROMICIN) BIOSYNTHESIS

We have cloned the seven genes that are responsible for biosynthesis o f the antibiotic fortimicin A (FTM A) using a recently developed self- cloning system that employs the plasmid vector pMO116 for Micromonospo ra olivasterospora. Five chimeric plasmids that restored FTM A product ion in M. olivasterospora mutants blocked at different biosynthetic st eps were isolated by shotgun cloning. Secondary transformation using o ther non-producing mutants showed that two additional FTM A biosynthet ic genes were included on these plasmids, and that at least four of th e genes were clustered. Interestingly AN38-1, a non-producing mutant t hat had a defect in dehydroxylation of a precursor of FTM A, was compl emented by the DNA fragment containing a neomycin resistance gene that had been cloned from a neomycin-producing strain (Micromonospora sp. FTM A non-producing strain) in the course of constructing the plasmid vector pMO116. These results clearly show that this novel gene cloning system in Micromonospora is of practical use.