Lipid-mediated nuclear moonlighting of cytosolic glyceraldehyde-3-phosphate dehydrogenase in plant heat response

Cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC) is a glycolytic enzyme, but it undergoes stress-induced nuclear translocation for moonlighting and regulating gene expression. To elucidate how the cytosolic enzyme moves into the nuclei under stress, we show that the plasma membrane-associated phospholipase D{delta}(PLD{delta}) and its product phosphatidic acid (PA) promote heat-induced nuclear translocation of GAPC. The GAPC nuclear accumulation and Arabidopsis seedling tolerance to heat stress were reduced in pld{delta}, which was restored by genetic complementation with intact PLD{delta}, but not with catalytically inactive enzyme. GAPC overexpression enhanced the seedling thermotolerance and the expression of heat-inducible genes, but this was not observed when GAPC was overexpressed in the pld{delta} background. The GAPC nuclear accumulation and seedling thermotolerance were also decreased by application with a vesicle trafficking inhibitor brefeldin A (BFA) or zinc that inhibited the PA-GAPC interaction. Heat stress elevated PA levels in nuclei from wild-type, but not from pld{delta} and BFA-treated plants. Lipid labeling and fluorescence resonance energy transfer analyses demonstrated heat-induced nuclear co-localization of PA and GAPC, which was impaired by BFA or zinc treatment. Taken together, our data suggest that PLD{delta}-produced PA mediates nuclear translocation of GAPC via lipid-protein interaction and vesicle trafficking for plants to cope with heat. One sentence summaryThe lipid mediator phosphatidic acid produced by a plasma membrane-associated phospholipase D mediates the nuclear moonlighting of cytosolic glyceraldehyde-3-phosphate dehydrogenase under heat.