title: Mutation of the TGD1 chloroplast envelope protein affects phosphatidate metabolism in Arabidopsis.
abstract: Phosphatidate (PA) is a central metabolite of lipid metabolism and a signaling molecule in many eukaryotes, including plants. Mutations in a permease-like protein, TRIGALACTOSYLDIACYLGLYCEROL1 (TGD1), in Arabidopsis thaliana caused the accumulation of triacylglycerols, oligogalactolipids, and PA. Chloroplast lipids were altered in their fatty acid composition consistent with an impairment of lipid trafficking from the endoplasmic reticulum (ER) to the chloroplast and a disruption of thylakoid lipid biosynthesis from ER-derived precursors. The process mediated by TGD1 appears to be essential as mutation of the protein caused a high incidence of embryo abortion. Isolated tgd1 mutant chloroplasts showed a decreased ability to incorporate PA into galactolipids. The TGD1 protein was localized to the inner chloroplast envelope and appears to be a component of a lipid transporter. As even partial disruption of TGD1 function has drastic consequences on central lipid metabolism, the tgd1 mutant provides a tool to explore regulatory mechanisms governing lipid homeostasis and lipid trafficking in plants.
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Changcheng
authors.initials: C
authors.lastname: Xu
authors.forename: Jilian
authors.initials: J
authors.lastname: Fan
authors.forename: John E
authors.initials: JE
authors.lastname: Froehlich
authors.forename: Koichiro
authors.initials: K
authors.lastname: Awai
authors.forename: Christoph
authors.initials: C
authors.lastname: Benning
mesh_terms: D017360:Arabidopsis / Q000196:embryology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001693:Biological Transport, Active / Q000502:physiology; D002736:Chloroplasts / Q000378:metabolism* / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000378:metabolism; D038983:Galactolipids / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D007425:Intracellular Membranes / Q000378:metabolism; D050356:Lipid Metabolism / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics*; D010743:Phospholipids / Q000378:metabolism*; D010938:Plant Oils / Q000378:metabolism; D012639:Seeds / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D038983:Galactolipids; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010743:Phospholipids; D010938:Plant Oils; C475468:TGD1 protein, Arabidopsis