Biogenesis of chromomycin A3 by Streptomyces griseus.

The biosynthesis of chromomycin A3 was investigated using 13C-labeled acetates, methionine and glucose, and 13C,18O-labeled acetate. 13C NMR spectral analysis demonstrated that: Aglycone assembly occurs by combining at least two polyketide chains; three of nine oxygen atoms of the aglycone originate from acetate precursor oxygen atoms; carbon methylations on the aromatic ring at C-7, on the chromose B sugar, and two O-methylations appear to be carried out by S-adenosyl-methionine requiring methyl transferases; and glucose is the precursor for all the sugars.