Cloning, expression, and chromosomal localization of human arachidonic acid-preferring acyl coa synthetase

Fatty acid acyl CoA synthetase (EC 6.2.1.3) which converts free fatty acid into fatty acyl CoA esters plays an essential role in lipid biosynthesis and fatty acid degradation. An acyl CoA synthetase activity with marked specificity for arachidonic acid was described previously and proposed to be a mechanism to precisely control the level of free arachidonic acid under physiological condition. The level of this fatty acid has been demonstrated to be an important signal in apoptosis and cell proliferation. We report here die cloning of a S.O kb full length human acyl CoA synthetase 4 (hACS4) cDNA by screening a brain library. The predicted amino acid sequence of KACS4 showed 97% amino acid identity to aie rat enzyme. By Western blot and acyl CoA synthetase enzymatic assay, we found that the cDNA encodes a functional acyl CoA synthetase with a molecular weight of -75 KD. The activity expressed by the KACS4 cDNA exhibited a significant arachidonic acid-preference over several tested fatty acids such as oleic acid and palmitic acid, indicating a substrate preference for arachidonic acid. In addition, we also studied the tissue distribution of hACS4 expression by Northern hybridization. Placenta, brain, testis, ovary, spleen and adrenal cortex had the highest level of the KACS4 mRNA, whereas die GI system had the lowest. Finally, we mapped the human ACS4 gene to chromosome Xq23 by FISH analysis.