The Evolutionary Pattern and the Regulation of Stearoyl-CoA Desaturase Genes

Abstract

Stearoyl-CoA desaturase (SCD) is a key enzyme that converts saturated fatty acids (SFAs) to monounsaturated fatty acids (MUFAs) in the biosynthesis of fat. To date, two isoforms ofscdgene (scd1andscd5) have been found widely existent in most of the vertebrate animals. However, the evolutionary patterns of both isofoms and the function ofscd5are poorly understandable. Herein, we aim to characterize the evolutionary pattern ofscdgenes and further predict the function differentiation ofscdgenes. The sequences ofscdgenes were highly conserved among eukaryote. Phylogenetic analysis identified two duplications ofscdgene early in vertebrate evolution. The relative rate ratio test, branch-specificdN/dSratio tests, and branch-sitedN/dSratio tests all suggested that thescdgenes were evolved at a similar rate. The evolution ofscdgenes among eukaryote was under strictly purifying selection though several sites inscd1andscd5were undergone a relaxed selection pressure. The variable binding sites by transcriptional factors at the 5′-UTR and by miRNAs at 3′-UTR ofscdgenes suggested that the regulators ofscd5may be different from that ofscd1. This study promotes our understanding of the evolutionary patterns and function of SCD genes in eukaryote.