Biosynthesis and elongation of short- and medium-chain-length fatty acids |
| |
| Authors: | van der Hoeven R S Steffens J C |
| |
| Affiliation: | Department of Plant Breeding and Biometry, 252 Emerson Hall, Cornell University, Ithaca, New York 14853, USA. |
| |
| Abstract: | Short- and medium-chain-length fatty acids (FAs) are important constituents of a wide array of natural products. Branched and straight short-chain-length FAs originate from branched chain amino acid metabolism, and serve as primers for elongation in FA synthase-like reactions. However, a recent model proposes that the one-carbon extension reactions that utilize 2-oxo-3-methylbutyric acid in leucine biosynthesis also catalyze a repetitive one-carbon elongation of short-chain primers to medium-chain-length FAs. The existence of such a mechanism would require a novel form of regulation to control carbon flux between amino acid and FA biosynthesis. A critical re-analysis of the data used to support this pathway fails to support the hypothesis for FA elongation by one-carbon extension cycles of alpha-ketoacids. Therefore, we tested the hypothesis experimentally using criteria that distinguish between one- and two-carbon elongation mechanisms: (a) isotopomer patterns in terminal carbon atom pairs of branched and straight FAs resulting from differential labeling with [(13)C]?cetate; (b)(13)C]threonine labeling patterns in odd- and even chain length FAs; and (c) differential sensitivity of elongation reactions to inhibition by cerulenin. All three criteria indicated that biosynthesis of medium-chain length FAs is mediated primarily by FA synthase-like reactions. |
| |
| Keywords: | |
| 本文献已被 PubMed 等数据库收录！ |
|
