Studies on the Biosynthesis of Antimycin A

The incorporation of 14C-labeled glucose, shikimate, benzoate, L-phenylalanine, and DL-tryptophan into antimycin A by Streptomyces AY-B-265 was examined. The most efficient incorporation was observed with L-phenylalanine-14C (U) (0.18%) and variously 14C-labeled DL-tryptophan (up to 2.0%). Analysis of degradation products from 14C-labeled antimycin produced from benzene-ring-14C-DL-tryptophan and L-phenylalanine-14C (U) showed a high proportion of the isotope present in the 3-aminosalicylic acid residue. Incorporation of 2-ring-14C-DL-tryptophan followed by degradation of the antimycin demonstrated that carbon-2 of the indole ring was incorporated into the 3-formamido carbonyl of antimycin in high yield. Tryptophan dilution studies suggested a fairly large tryptophan pool in cells transferred to resting medium for incorporation studies.