Fatty acid desaturase 3-mediated α-linolenic acid biosynthesis in plants.

Omega (ω)-3 fatty acids (FAs) are essential components of cell membranes that also serve as precursors of numerous regulatory molecules. α-linolenic acid (ALA), one of the most important ω3 FAs in plants, is synthesized in both the plastid and extraplastidial compartments. FA Desaturase (FAD) 3 is an extraplastidial enzyme that converts linoleic acid (LA) to ALA. Phylogenetic analysis suggested that FAD3 proteins are distinct from FAD7 and FAD8 desaturases, which convert LA to ALA in plastids. Structural analysis of FAD3 proteins indicated a positive relationship between enzymatic activity and transmembrane pore length and width. An inverse relationship between temperature and ALA biosynthesis was also evident, with ALA accumulation decreasing with increasing temperature. These findings suggest that certain FAD3 enzymes are more effective at converting LA to ALA than others. This information could potentially be used to engineer crop plants with higher levels of ALA.