FabD gene

For the malonate group to be used for fatty acid synthesis, it must first be transferred from malonyl-CoA to malonyl-ACP by the 32.4-kDa monomeric malonyl-CoA ACP transacy-lase, the product of the fabD gene (Fig. 2). A stable malonyl-serine enzyme intermediate is formed during the course of the FabD reaction, and subsequent nucleophilic attack on this ester by the sulfhydryl of ACP yields malonyl-ACP. The high reactivity of the serine in malonyl-ACP transacylase is due to the active site being composed of a nucleophilic elbow as observed in alpha/beta hydrolases. The serine is hydrogen bonded to His-201 in a fashion similar to serine hydrolases. 

Figure 2. Analyses of transgenic seeds during development. A Immunoblots with anti-E. coli MCAT arid HDD, B Northemblot analysis of steady state mRNA levels in a BN93 transformant, hybridized with an E. coli fabH probe, C MCAT, KAS III and HDD relative temporal enzyme patterns, compared to control plants (Not on scale). Numbers indicate the developmental stage of the seeds (weeks after anthesis), M, mature seeds, C, control plant, L, leaf tissue. All these data are quantified per seed, 53 and 50 indicate constructs of the E, coli fabD gene, with and without the transitpeptide, expressed in E, coli.

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