The biosynthesis of caerulomycin A in Streptomycescaeruleus. Incorporation of 14C- and 13C-labeled precursors and analyses of labeling patterns by 13C nmr

Carbon-13 nuclear magnetic resonance spectroscopy of caerulomycin A (1) produced by cultures of Streptomycescaeruleus has shown that [1-13C]acetate labels C-2, C-4, and C-4′, whilst [1,2-13C]acetate enriches these carbons plus C-2′, C-3, C-3′, C-5′, and C-6′. The results establish that acetate is incorporated with little dilution at C-3 and C-4 in the substituted ring of 1, whereas C-2, and C-2′ to C-6′ of the unsubstituted ring, are assembled from lysine via the symmetrical intermediate 2S,6S-diaminopimelic acid. The methoxyl carbon incorporates label from DL-[3-13C]serine, but this precursor does not enrich C-5, C-6, or C-7 of the substituted ring, and the origins of these carbons remain undetermined.