mutabilis, Gonium pectorale, Auxenochlorella protothecoides and Chlorella variabilis, respectively.įigure 3. Evaluation of TAG biosynthesis in the yeast quadruple mutant (H1246) complemented with UpDGAT genes. UlDGAT, UmDGAT, GpDGAT, ADGAT and CDGAT were obtained from Ulva linza, U. Identical amino acid residues are highlighted in blue. Bootstrapping with 1000 replicates was used to establish the confidence limits of the tree branches.įigure 2. Homology comparison of the amino acid sequences of UpDGAT1 with DGAT1s from other algal species. Colored branches indicate different groups of proteins. Gene sequences other than Ulva DGATs were shown by their nomenclatures found in NCBI. prolifera.įigure 1. Phylogenetic tree of DGAT gene families reconstructed by the neighbor-joining (NJ) method. The present study provides clues to the functions of UpDGAT1 in TAG accumulation in, and stress adaptation of, U. High salinity and high temperature stresses increased UpDGAT1 expression and TAG accumulation in U. Lipid analysis of yeast cells revealed that UpDGAT1 showed broad substrate specificity, accepting saturated as well as mono- and polyunsaturated acyl-CoAs as substrates. Results of thin-layer chromatography and BODIPY staining indicated that UpDGAT1 was able to restore TAG synthesis and lipid body formation in the yeast. The activity of UpDGAT1 was confirmed by heterologous expression in a Saccharomyces cerevisiae TAG-deficient quadruple mutant. The present work identified and isolated a novel gene, UpDGAT1, from the green tide alga Ulva prolifera. Acyl-CoA: diacylglycerol acyltransferase (DGAT) catalyzes the final and only committed acylation step in the synthesis of TAGs in eukaryotes.
Triacylglycerols (triglycerides, TAGs) are the major carbon and energy storage forms in various organisms, and important components of cellular membranes and signaling molecules they have essential functions in multiple physiological processes and stress regulation.
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