Phosphatidic acid (PA) and Lysophosphatidic acid acyltransferases (LPAATs) might be critical for the secretory pathway. Four extra-plastidial LPAATs (LPAAT2, 3, 4 and 5) were identified in A. thaliana. These AtLPAATs, display a specific enzymatic activity converting lysophosphatidic acid (LPA) to PA and are located in the endomembrane system. We investigate a putative role of the AtLPAATs 3, 4 and 5 in the secretory pathway of root cells through genetical (knock-out mutants), biochemical (activity inhibitor, lipid analyses) and imaging (live and immuno-confocal microscopy) approaches. Treating a lpaat4;lpaat5 double mutant with the LPAAT inhibitor CI976 showed a significant decrease in primary root growth. The trafficking of the auxin transporter PIN2 was disturbed in this lpaat4;lpaat5 double mutant treated with CI976, whereas trafficking of H+-ATPases was unaffected. The lpaat4;lpaat5 double mutant is sensitive to salt stress and the trafficking of the aquaporin PIP2;7 to the plasma membrane in the lpaat4;lpaat5 double mutant treated with CI976 was reduced. We measured the amounts of neo-synthesized PA in roots, and found a decrease in PA only in the lpaat4;lpaat5 double mutant treated with CI976, suggesting that the protein trafficking impairment was due to a critical PA concentration threshold.
Wattelet-Boyer, ValérieLe Guédard, MarinaDittrich-Domergue, FranziskaManeta-Peyret, LillyKriechbaumer, Verena Boutté, YohannBessoule, Jean-JacquesMoreau, Patrick
Department of Biological and Medical Sciences
Year of publication: 2021Date of RADAR deposit: 2021-11-10