Cloning and functional characterization of long-chain acyl-CoA synthetase 1 from the mesocarp of African oil palm (Elaeis guineensis Jacq.)

Abstract

African oil palm (Elaeis guineensis Jacq.) is the highest-yielding oil crop in the world. Recent studies have shown the importance of long-chain acyl-CoA synthetases (LACSs) in lipid biosynthesis and degradation, but few studies have focused on oil palm. In this work, we found that transcription of EgLACS1was positively correlated with lipid accumulation in the oil palm mesocarp. In order to clarify the role of EgLACS1 on lipid metabolism, three variants of the EgLACS1 gene were cloned from oil palm and designated EgLACS1-V1, EgLACS1-V2, and EgLACS1-V3. Sequence analysis revealed that the three variant proteins contained several highly conserved motifs, shared important sequence similarities with other known LACS1s, and demonstrated that EgLACS1-V1, EgLACS1-V2 and EgLACS1-V3 were 666-, 664- and 601-aminoacid proteins, respectively. All of the three variant genes encodingEgLACS1 were expressed and tested for their functionality in an acyl-coenzyme-A synthetase- (ACS-) deficient mutant yeast strain YB525. Only EgLACS1-V1 and EgLACS1-V2 could rescue the growth deficiency (an inability to grow on a fatty acid auxotrophic medium) of YB525 in complementation tests. Using a fluorescent fatty acid analogue confirmed that EgLACS1-V1 and EgLACS1-V2 facilitated exogenous fatty acid uptake. EgLACS1 overexpression in yeast reduced fatty acid content. All these results suggested that not only did both the EgLACS1-V1 and EgLACS1-V2 enzymes exhibit acyl-coenzyme-A activities, but that they were also involved in the transfer of fatty acid-coenzyme A. They may also take part in the storage of lipid during fruit development in oil palm. The characterization of EgLACS1 will provide a molecular basis for the study of acyl-coenzyme A synthetase-mediated lipid synthesis and degradation in oil palm.