FAD2 and FAD3 Desaturases Form Heterodimers That Facilitate Metabolic Channeling in Vivo

Abstract

Background: Plant fatty acid desaturase (FAD) enzymes determine the desaturation status of plant lipids. Results: FAD enzymes form homo-and heterodimers; FAD2-FAD3 heterodimers can channel oleate to linolenate without releasing the linoleate intermediate. Conclusion:A physiological function for FAD2-FAD3 heterodimers has been demonstrated. Significance: That monoenes can be channeled to trienes has implications for engineering desired plant fatty acid compositions.

Overexpression of Arabidopsis WRI1 enhanced seed mass and storage oil content in Camelina sativa

“…To our knowledge, this study is the first report to generate transgenic C. sativa plants with enhanced oil content of seeds. In addition, there is a significant increase in the levels of 18:2 plus 18:3 in T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 16:0 18: (Lou et al 2014). It was observed that the levels of seed oils increased by approximately 10-20 % in T 4 seeds of transgenic Arabidopsis overexpressing AtWRI1 (Cernac and Benning 2004).…”

Two Acyltransferases Contribute Differently to Linolenic Acid Levels in Seed Oil

“…The increase in 18:2n-6 at the expense of 18:3n-3 suggests that the usage of 18:2n-6 by PDAT supersedes that of FAD3, and 18:2n-6 is to a high degree removed from PC by PDAT before it is desaturated to 18:3n-3. Thus, in C. sativa, FAD2/ FAD3 heterodimer formation to form 18:3n-3 directly from 18:1n-9 without the intermediate release of 18:2n-6 (Lou et al, 2014) does not seem to be a major pathway. The reason for 18:2n-6 being increased dramatically in TAG could be that the enzyme has a specificity for either or both 18:2n-6-containing DAG and PC as a substrate.…”

Genome Wide Analysis of Fatty Acid Desaturation and Its Response to Temperature

“…The enzymes that are primarily responsible for producing PUFAs in seed oils are the microsomal v-6 and v-3 fatty acid desaturases FAD2 and FAD3, which act in sequence to convert oleic acid (18:1) to linoleic acid (18:2) and then to a-linolenic acid (18:3), while the fatty acid is esterified to the sn-2 position of PC (Miquel and Browse, 1992;Browse et al, 1993;Lou et al, 2014). Temperature can influence the degree of microsomal fatty acid desaturation indirectly through its effects on substrate availability (Harris and James, 1969;Browse and Slack, 1983;Rolletschek et al, 2007;Li et al, 2015).…”