Regiobiochemical analysis reveals the role of castor LPAT2 in the accumulation of hydroxy fatty acids in transgenic lesquerella seeds

• Published in: Biocatalysis and agricultural biotechnology Vol. 25; p. 101617
• Main Authors: Chen, Grace Qianhong, Lin, Jiann-Tsyh, van Erp, Harrie, Johnson, Kumiko, Lu, Chaofu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2020
• Subjects: Hydroxy fatty acid; Lesquerella; Lysophosphatidic acid acyltransferase; Regioisomer; Ricinoleic acid; Seed triacylglycerol; Seed triacylglycerol; Hydroxy fatty acid; Ricinoleic acid; Lesquerella; Regioisomer; Lysophosphatidic acid acyltransferase
• ISSN: 1878-8181; 1878-8181
• DOI: 10.1016/j.bcab.2020.101617

Castor lysophosphatidic acid acyltransferase 2 (RcLPAT2) increases hydroxy fatty acids (HFA) content at the sn-2 position of seed triacylglycerols (TAG). Determining TAG species and their regioisomers from transgenic lesquerella seeds expressing RcLPAT2 provides information for understanding the mechanisms of RcLPAT2 in HFA-containing TAG biosynthesis. Using high-performance liquid chromatography and electrospray ionization mass spectrometry, four molecular species of 3-HFA-TAG (tri-HFA-TAG), five of 2-HFA-TAG, and nine of 1-HFA-TAG were revealed, and the ratios of the regioisomers of these molecular species were quantified. HFA were identified as lesquerolic acid (Ls, OH20:1), ricinoleic acid (R, OH18:1), auricolic acid (Au, OH20:2), and densipolic acid (De, OH18:2). Ls was predominately at the sn-1,3 positions in 1-, 2- and 3-HFA-TAG. RcLPAT2 increased significantly all four kinds of HFA at the sn-2 position of the 3-HFA-TAG, and the content of regioisomer with R at the sn-2 in LsLsR alone counted about 91–94% of the total R in the transgenics. RcPLAT2 slightly decreased each 2-HFA-TAG species. There was no Ls, R and De, but trace amount of Au found at the sn-2 position of 2-HFA-TAG. RcLPAT2 also elevated each 1-HFA-TAG species with Ls found to be the only HFA, and likely at the sn-3 position. •Regioisomers of triacyglycerols in lesquerella seed are altered by a castor enzyme.•Castor lysophosphatidic acid acyltransferase 2 increases tri-hydroxyfattyacids-triacylglycerols.•Multiple endogenous enzymes limit the acylation of ricinoleate in lesquerella seed oil.