Qin Y-M, Pujol FM, Hu C-Y, Feng J-X, Kastaniotis AJ, Hiltunen JK, Zhu YX

J Exp Bot. 2007;58(3):473–81

3-ketoacyl-CoA synthase catalyses the initial condensation reaction during fatty acid elongation using malonyl-CoA and long-chain acyl-CoA as substrates. Previously, it was reported that several genes encoding putative cotton 3-ketoacyl-CoA synthases were significantly up-regulated during early cotton fibre development. In this study, GhCER6 cDNA that contains an open reading frame of 1479 bp, encoding a protein of 492 amino acidresidues homologous to the Arabidopsis condensing enzyme CER6, was isolated and cloned. In situ hybridization results demonstrated thatGhCER6 mRNA was detected only in the elongating wild-type cotton fibre cells. When GhCER6 was transformed to the Saccharomyces cerevisiae elo3 deletion mutation strain that was deficient in the production of 26-carbon fatty acids and displayed a very slow-growth phenotype, the mutant cells were found to divide similarly compared with those of the wild-type cells. Further, heterologous expression of GhCER6 restored the viability of the S. cerevisiae haploid elo2 and elo3 double-deletion strain. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis showed that GhCER6 was enzymatically active since the yeast elo2 and elo3 double-deletion mutant expressing the cotton gene produced very-long-chain fatty acids that are essential for cell growth. The results suggest that GhCER6 encodes a functional 3-ketoacyl-CoA synthase.