Isolation and characterization of a long-chain acyl-coenzyme A synthetase encoding gene from the marine microalga Nannochloropsis oculata

Acyl-coenzyme A synthetases (ACSs) are associated with the anabolism and catabolism of fatty acids and play fundamental roles in various metabolic pathways. The cDNA of long-chain acyl-coenzyme A synthetase (LACS), one of the ACSs, was isolated from Nannochloropsis oculata and named as NOLACS. The predicted amino acid sequence was highly similar to LACSs of other species. NOLACS encodes a long-chain acyl-coenzyme A synthetase; it recovered the function of LACS in Saccharomyces cerevisiae YB525 (a LACS-deficient yeast strain). The substrate specificity of the enzyme was also assayed in yeast. It was found that NOLACS can activate saturated fatty acids (C12:0, C14:0, C16:0, and C18:0) and some unsaturated fatty acids (C18:2Δ^{9, 12} and C20:2Δ^{11, 14}) with a preference for long-chain fatty acids. Our findings will provide a deep understanding of CoA-dependent fatty acid activation and also make some contribution to understanding the metabolic pathways of lipids in Nannochloropsis. These findings will also facilitate studies on the regulation of gene expression and genetic modification of fatty acid synthesis and storage of N. oculata.