INVESTIGATIONS ON THE BIOSYNTHESIS OF THE ANGUCYCLINE GROUP ANTIBIOTICS AQUAYAMYCIN AND THE URDAMYCIN-A AND URDAMYCIN-B - RESULTS FROM THE STRUCTURAL-ANALYSIS OF NOVEL BLOCKED MUTANT PRODUCTS

In order to investigate mid and early biosynthetic steps of angucyclin e group antibiotics, approximately 400 mutants of the urdamycin produc er Streptomyces fradiae (strain Tu 2717) were prepared, of which ca. 1 0 % were selected for further investigations. The selection criterion, i. e., the consideration of only pale-colored metabolite-producing bl ocked mutants, yielded several mutants whose block was in close proxim ity to the known late-stage biosynthetic steps. The product patterns w ere characterized by TLC and HPLC methods, and the structures of five new and one known (but previously not detectable) metabolites were elu cidated (3-8). Their roles in the biosynthetic pathway leading to aqua yamycin (1) and on to the urdamycins A (2) and B (9) are proposed. The glycosylation sequence of the urdamycin group and two additional earl ier biosynthetic steps leading to aquayamycin (1), the most important angucyclinone, were established in this way.