CLONING, SEQUENCING, AND ANALYSIS OF AKLAVIKETONE REDUCTASE FROM STREPTOMYCES SP STRAIN C5

DNA sequence analysis of a region of the Streptomyces sp. strain C5 da unomycin biosynthesis gene cluster, located just upstream of the dauno mycin polyketide biosynthesis genes, revealed the presence of six comp lete genes. The two genes reading right to left include genes encoding the potentially translationally coupled gene products, an acyl carrie r protein and a ketoreductase, and the four genes reading divergently, left to right, include two open reading frames of unknown function fo llowed by a gene encoding an apparent glycosyltransferase and dauE, en coding aklaviketone reductase. Extracts of Streptomyces lividans TK24 containing recombinant DauE catalyzed the NADPH-specific conversion of aklaviketone, maggiemycin, and 7-oxodaunomycinone to aklavinone, epsi lon-rhodomycinone, and daunomycinone, respectively. Neither the produc t of dauB nor that of the ketoreductase gene directly downstream of th e acyl carrier protein gene demonstrated aklaviketone reductase activi ty.