Use of 13C in biosynthetic studies. The labeling pattern in dihydrofusarubin enriched from [13C]- and [13C, 2H]acetate in cultures of Fusarium solani

Abstract

The pattern of 13C and 2H incorporation from [1-13C]-, [2-13C]-, [1-13C0;1;1,2-13C1;0;1]-, and [2-13C0;1,2-2H3;3]acetate into dihydrofusarubin 1, produced by cultures of Fusariumsolani, has been determined by 13C and 2H nmr of the derivatives anhydrofusarubin 3 and anhydrofusarubin diacetate 4. The results show that 1 is biosynthesized from seven uniformly-incorporated acetate units with C-3, C-11 originating from the "starter" unit. They strongly suggest that linear head-to-tail condensation of an acetate and six malonate units forms a single-chain heptaketide intermediate. The evidence also suggests that, during conversion of [13C, 2H]-labeled acetyl-CoA to malonyl-CoA, 2H is transferred to biotin carboxyl carrier protein where it does not exchange rapidly with the medium and is available for conversion of endogenous malonyl-CoA to [2H]-enriched acetyl-CoA.