Expression,regulation and binding affinity of fatty acid-binding protein 2 in Spodoptera litura

Fatty acid-binding proteins(FABPs) are a family of lipid chaperones, which contribute to systemic metabolic regulation through diverse lipid signalings. In this study, a midgut-specific FABP gene(Slfabp2) was cloned from Spodoptera litura. RT-PCR and Western blot analysis indicated that RNA and protein levels of SlFABP2 gradually increased and reached a peak at the prepupal stage and maintained a high level during the pupal stage. The expression of SlFABP2 protein was induced by starvation treatment. In vitro binding assay revealed that the recombinant SlFABP2 had high affinities of binding long-chain fatty acids, such as palmitic acid, arachidonate and oleic acid. The results suggest that SlFABP2 may have a unique function that transports intracellular fatty acids and can regulate the metabolism of lipids in metamorphosis. This work provides experimental clues for understanding the potential function of SlFABP2 in fatty acid metabolism in S. litura.