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

Abstract

The pattern of 13 C and 2 H incorporation from [1- 13 C]-, [2- 13 C]-, [1- 13 C 0;1;1 ,2- 13 C 1;0;1 ]-, and [2- 13 C 0;1 ,2- 2 H 3;3 ]acetate into dihydrofusarubin 1, produced by cultures of Fusariumsolani, has been determined by 13 C and 2 H 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 [ 13 C, 2 H]-labeled acetyl-CoA to malonyl-CoA, 2 H 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 [ 2 H]-enriched acetyl-CoA.