A Specialized Diacylglycerol Acyltransferase Contributes to the Extreme Medium-Chain Fatty Acid Content of Seed Oil.

Seed oils of many sp. contain >90% of medium-chain fatty acids, such as decanoic acid (10:0). These seed oils, which are among the most compositionally variant in the plant kingdom, arise from specialized fatty acid biosynthetic enzymes and specialized acyltransferases.

Structurally divergent lysophosphatidic acid acyltransferases with high selectivity for saturated medium chain fatty acids from Cuphea seeds.

Lysophosphatidic acid acyltransferase (LPAT) catalyzes acylation of the sn-2 position on lysophosphatidic acid by an acyl CoA substrate to produce the phosphatidic acid precursor of polar glycerolipids and triacylglycerols (TAGs). In the case of TAGs, this reaction is typically catalyzed by an LPAT2 from microsomal LPAT class A that has high specificity for C18 fatty acids containing Δ9 unsaturation. Because of this specificity, the occurrence of saturated fatty acids in the TAG sn-2 position is infrequent in seed oils.

A thraustochytrid diacylglycerol acyltransferase 2 with broad substrate specificity strongly increases oleic acid content in engineered Arabidopsis thaliana seeds.

Diacylglycerol acyltransferase (DGAT) catalyses the last step in acyl-CoA-dependent triacylglycerol (TAG) biosynthesis and is an important determinant of cellular oil content and quality. In this study, a gene, designated TaDGAT2, encoding a type 2 DGAT (DGAT2)-related enzyme was identified from the oleaginous marine protist Thraustochytrium aureum. The deduced TaDGAT2 sequence contains a ~460 amino acid domain most closely related to DGAT2s from Dictyostelium sp.

LC-PUFA from photosynthetic microalgae: occurrence, biosynthesis, and prospects in biotechnology.

Microalgae offer potential for numerous commercial applications, among them the production of long-chain polyunsaturated fatty acids (LC-PUFAs). These valuable fatty acids are important for a variety of nutraceutical and pharmaceutical purposes, and the market for these products is continually growing. An appropriate ratio of LC-PUFA of the ω-3 and ω-6 groups is vital for "healthy" nutrition, and adequate dietary intake has strong health benefits in humans.

Selection of a DGLA-producing mutant of the microalga Parietochloris incisa: I. Identification of mutation site and expression of VLC-PUFA biosynthesis genes.

Chemical mutagenesis of the phototrophic green microalga Parietochloris incisa, producing high amounts of arachidonic acid (ARA), resulted in selection of a mutant deficient in ARA and rich in dihomo-γ-linolenic acid (DGLA) and thus ∆5 desaturase defective. The mutagenesis produced a nonsense mutation in the ∆5 desaturase gene, resulting in alteration of the 62nd codon TGG into a stop codon. Thus, the polypeptide encoded by the mutant ∆5 desaturase gene is severely truncated and biochemically inactive, as was confirmed by heterologous expression in Saccharomyces cerevisiae.

Identification and characterization of Delta12, Delta6, and Delta5 Desaturases from the green microalga Parietochloris incisa.

The freshwater microalga Parietochloris incisa accumulates, under nitrogen starvation, large amounts of triacylglycerols containing approximately 60% of the omega6 very long-chain polyunsaturated fatty acid (VLC-PUFA), arachidonic acid. Based on sequence homology, we isolated three cDNA sequences from P. incisa, designated PiDesD12, PiDesD6, PiDesD5.

Cloning and characterization of the 6 polyunsaturated fatty acid elongase from the green microalga Parietochloris incisa.

The very-long-chain polyunsaturated fatty acid (VLC-PUFA), arachidonic acid (ARA, 20:4omega-6) is a component of neuron tissues such as brain and retina cells and a primary substrate for the biosynthesis of biologically active eicosanoids. The green freshwater microalga Parietochloris incisa (Trebouxiophyceae) has been shown to accumulate an extraordinary high content of ARA-rich triacylglycerols. It was thus interesting to characterize the genes involved in lipid biosynthesis in this alga.