Abstract
Microalgae have been emerging as an important source for the production of bioactive compounds. Marine diatoms can store high amounts of lipid and grow quite quickly. However, the genetic and biochemical characteristics of fatty acid biosynthesis in diatoms remain unclear. Glycerophospholipids are integral as structural and functional components of cellular membranes, as well as precursors of various lipid mediators. In addition, diacylglycerol acyltransferase (DGAT) is a key enzyme that catalyzes the last step of triacylglyceride (TAG) biosynthesis. However, a comprehensive sequence-structure and functional analysis of DGAT in diatoms is lacking. In this study, an isoform of diacylglycerol acyltransferase type 2 of the marine diatom Phaeodactylum tricornutum was characterized. Surprisingly, DGAT2 overexpression in P. tricornutum stimulated more oil bodies, and the neutral lipid content increased by 35%. The fatty acid composition showed a significant increase in the proportion of polyunsaturated fatty acids; in particular, EPA was increased by 76.2%. Moreover, the growth rate of transgenic microalgae remained similar, thereby maintaining a high biomass. Our results suggest that increased DGAT2 expression could alter fatty acid profile in the diatom, and the results thus represent a valuable strategy for polyunsaturated fatty acid production by genetic manipulation.
Highlights
Cell membranes are composed of proteins, phospholipids, and cholesterol
Proteomic profiling of oil bodies isolated from the green microalga C. reinhardtii identified 19 new proteins associated with lipid metabolism and a diacylglycerol acyltransferase was included [10]
To enhance polyunsaturated fatty acids (PUFAs) yield in oil-producing microalgae has become very attractive at present. These high-productivity microalgal strains can be achieved by genetic engineering based on the crucial enzymes that can be targeted for fatty acid biosynthesis and molecular understanding of lipid metabolic pathways in certain microalgae [15,16]
Summary
Cell membranes are composed of proteins, phospholipids, and cholesterol. Bipolar lipids including glycerophospholipids and sphingophospholipids can form cell membranes. Diacylglycerol acyltransferase (DGAT) is one of the most intensively studied enzymes in the entire acyl lipid metabolism. Proteomic profiling of oil bodies isolated from the green microalga C. reinhardtii identified 19 new proteins associated with lipid metabolism and a diacylglycerol acyltransferase was included [10]. To enhance PUFA yield in oil-producing microalgae has become very attractive at present These high-productivity microalgal strains can be achieved by genetic engineering based on the crucial enzymes that can be targeted for fatty acid biosynthesis and molecular understanding of lipid metabolic pathways in certain microalgae [15,16]. Molecular characterization of several enzymes involved in lipid accumulation has been conducted in mammals and plant [4,17,18,19,20], while such a study is urgently needed in diatoms for germplasm improvement. We first altered PUFA production by overexpressing DGAT2 in P. tricornutum
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