A permease-like protein involved in ER to thylakoid lipid transfer in Arabidopsis.
In eukaryotes, enzymes of different subcellular compartments participate in the assembly of membrane lipids. As a consequence, interorganelle lipid transfer is extensive in growing cells. A prominent example is the transfer of membrane lipid precursors between the endoplasmic reticulum (ER) and the photosynthetic thylakoid membranes in plants. Mono- and digalactolipids are typical photosynthetic membrane lipids. In Arabidopsis, they are derived from one of two pathways, either synthesized de novo in the plastid, or precursors are imported from the ER, giving rise to distinct molecular species. Employing a high-throughput robotic screening procedure generating arrays of spot chromatograms, mutants of Arabidopsis were isolated, which accumulated unusual trigalactolipids. In one allelic mutant subclass, trigalactosyldiacylglycerol1, the primary defect caused a disruption in the biosynthesis of ER-derived thylakoid lipids. Secondarily, a processive galactosyltransferase was activated, leading to the accumulation of oligogalactolipids. Mutations in a permease-like protein of the outer chloroplastic envelope are responsible for the primary biochemical defect. It is proposed that this protein is part of a lipid transfer complex.
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing 48824, USA.
Changcheng
C
Xu
Jilian
J
Fan
Wayne
W
Riekhof
John E
JE
Froehlich
Christoph
C
Benning
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002236:Carbohydrate Conformation; D002736:Chloroplasts / Q000201:enzymology; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000378:metabolism*; D005838:Genotype; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009154:Mutation; D010641:Phenotype; D016415:Sequence Alignment; D020524:Thylakoids / Q000737:chemistry / Q000378:metabolism*
D029681:Arabidopsis Proteins; D008563:Membrane Lipids; D026901:Membrane Transport Proteins; C475468:TGD1 protein, Arabidopsis