Fatty acid biosynthesis in eukaryotic photosynthetic microalgae: Identification of a microsomal delta 12 desaturase in Chlamydomonas reinhardtii

Abstract

Polyunsaturated fatty acids (PUFAs) are important components of infant and adult nutrition because they serve as structural elements of cell membranes. Fatty acid desaturases are responsible for the insertion of double bonds into pre-formed fatty acid chains in reactions that require oxygen and reducing equivalents. In this study, the genome-wide characterization of the fatty acid desaturases from seven eukaryotic photosynthetic microalgae was undertaken according to the conserved histidine-rich motifs and phylogenetic profiles. Analysis of these genomes provided insight into the origin and evolution of the pathway of fatty acid biosynthesis in eukaryotic plants. In addition, the candidate enzyme from Chlamydomonas reinhardtii with the highest similarity to the microsomal delta 12 desaturase of Chlorella vulgaris was isolated, and its function was verified by heterologous expression in yeast (Saccharomyces cerevisiae).

Agrigenomics for Microalgal Biofuel Production: An Overview of Various Bioinformatics Resources and Recent Studies to Link OMICS to Bioenergy and Bioeconomy

“…As a fundamental step in their direction, in silico studies aimed at prediction of candidate genes whose combination determines the inherent fatty ester composition of microalgae has been reported (Chi et al, 2008;Hashimoto et al, 2008). These studies conclusively highlight the potential utility of the emerging ''omic'' approaches in providing greater insights into genome structure and lipid metabolism of various microalgal species.…”

The Green Microalga Chlamydomonas reinhardtii Has a Single -3 Fatty Acid Desaturase That Localizes to the Chloroplast and Impacts Both Plastidic and Extraplastidic Membrane Lipids

“…These are crfad6 (hf-9), an insertional mutant for the plastidial v-6 desaturase FAD6 (Sato et al, 1995), and microRNA-based silenced lines for the D4 desaturase CrD4FAD (Zäuner et al, 2012). The putative microsomal D12 desaturase FAD2 (Chi et al, 2008) and front-end v-13 desaturase (Kajikawa et al, 2006) have been characterized by heterologous expression in the methylotrophic yeast Pichia pastoris, but no mutant is available. Moreover, although v-3 PUFA is the most abundant fatty acid class in C. reinhardtii, the v-3 desaturase remains uncharacterized, and no mutant with specific reduction in v-3 content has been isolated so far.…”

A Cytochrome b 5 -Containing Plastid-Located Fatty Acid Desaturase from Chlamydomonas reinhardtii

“…This 16:4 acyl group is found only in trace amounts in other membrane lipids. Genes necessary for the introduction of the double bonds into lipid acyl groups in Chlamydomonas have been identified and characterized (6,16,36), except for this MGDGspecific ⌬4-desaturase.…”