title: Ansamycin biogenesis: studies on a novel rifamycin isolated from a mutant strain of Nocardia mediterranei.
abstract: A novel ansamycin, rifamycin W, was isolated from a mutant strain of Nocardia mediterranei. The metabolic origin of rifamycin W was studied by (13)C nuclear magnetic resonance spectroscopy. Examination of the proton-decoupled pulse and Fourier transform (13)C spectra of rifamycin W biogenetically enriched with [1-(13)C]-, [2-(13)C]-, and [3-(13)C]propionate and with [1-(13)C]acetate has revealed that the alignment of acetate and propionate units corresponds to that previously proposed for rifamycin S. Washed mycelium from a rifamycin B-producing strain of N. mediterranei transformed rifamycin W into rifamycin B. We suggest that rifamycin W is a normal intermediate in the biosynthesis of the other rifamycins. These results, together with the structural similarity of rifamycin W to the streptovaricins, reinforce our hypothesis that a common progenitor is involved in the biogenesis of all naphthalenic ansamycins.
mesh_terms: D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D005583:Fourier Analysis; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009154:Mutation; D009615:Nocardia / Q000032:analysis / Q000378:metabolism*; D012294:Rifamycins / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D012294:Rifamycins