PtLTPG14-PtGAPC1 mediates lipid metabolism and glycolmetabolism in popular by G3P regulatory loop

Lipid comprises the basic skeleton of the plasma membrane and provides energy in various biological life activities. Although the essential roles of lipid transfer proteins (LTPs) have been proven in transporting lipids, the detailed feedback regulatory between lipid and carbohydrate metabolisms has not previously been identified in poplar (Populus trichocarpa). Here, poplar glycosylphosphatidylinositol-anchored lipid transfer protein gene PtLTPG14, as a homologous gene with Arabidopsis LTPG1, has been associated with fatty acids (FAs). The overexpression of PtLTPG14 not only has effects on the lipid derivatives, including unsaturated FAs (UFAs), medium-chain FAs (MCFAs), and long-chain FAs (LCFAs) but also has significantly down-regulated carbohydrate metabolites. A series of putative proteins interacting with PtLTPG14, including poplar cytosolic glyceraldehyde-3-phosphate dehydrogenase1 (PtGAPC1), have been identified by pull-down assays and PtLTPG14 displayed strong interaction with PtGAPC1 in vivo. PtLTPG14-overexpressed (OE) poplars exhibited higher abundances of FA biosynthetic genes and higher transcript levels of PtGAPC1. Therefore, PtLTPG14 can regulate expression levels of FA biosynthetic genes and PtLTPG14-PtGAPC1 complex participants in lipid and glucose metabolisms through regulating glyceraldehyde-3-phosphate (G3P) accumulation in poplar. The information showed that the comprehensive feedback regulatory loop among PtLTPG14, PtGAPC1, and G3P is implicated in lipid and glucose metabolisms.

Automated summary

This study identifies the involvement of the PtLTPG14 gene in the feedback regulation of lipid and glucose metabolism in poplar trees. The overexpression of PtLTPG14 affects lipid derivatives and down-regulates carbohydrate metabolites. PtLTPG14 interacts with PtGAPC1 and regulates the expression of FA biosynthetic genes through G3P accumulation.