A genetic approach to the biosynthesis of the rifamycin-chromophore in Nocardia mediterranei. IV. Identification of 3-amino-5-hydroxybenzoic acid as a direct precursor of the seven-carbon amino starter-unit.

3-Amino-5-hydroxybenzoic acid was investigated for its ability to induce rifamycin biosynthesis in an appropriate mutant of Nocardia mediterranei and identified as a direct precursor of the seven-carbon amino starter-unit for the biosynthesis of ansamycins. A model for the biosynthesis of different types of ansamycins is presented and discussed.