title: Genetic analysis of Arabidopsis mutants impaired in plastid lipid import reveals a role of membrane lipids in chloroplast division.
abstract: The biogenesis of photosynthetic membranes in plants relies largely on lipid import from the endoplasmic reticulum (ER) and this lipid transport process is mediated by TGD proteins in Arabidopsis. Such a dependency of chloroplast biogenesis on ER-to-plastid lipid transport was recently exemplified by analyzing double mutants between tgd1-1 or tgd4-3 and fad6 mutants. The fad6 mutants are defective in the desaturation of membrane lipids in chloroplasts and therefore dependent on import of polyunsaturated lipid precursors from the ER for constructing a competent thylakoid membrane system. In support of a critical role of TGD proteins in ER-to-plastid lipid trafficking, we showed that the introduction of the tgd mutations into fad6 mutant backgrounds led to drastic reductions in relative amounts of thylakoid lipids. Moreover, the tgd1-1 fad6 and tgd4-3 fad6 double mutants were deficient in polyunsaturated fatty acids in chloroplast membrane lipids, and severely compromised in the biogenesis of photosynthetic membrane systems. Here we report that these double mutants are severely impaired in chloroplast division. The possible role of membrane lipids in chloroplast division is discussed. :
authors.affiliation: Biology Department, Brookhaven National Laboratory, Upton, NY, USA.
authors.forename: Jilian
authors.initials: J
authors.lastname: Fan
authors.forename: Changcheng
authors.initials: C
authors.lastname: Xu
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism*; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D050356:Lipid Metabolism / Q000235:genetics / Q000502:physiology; D008563:Membrane Lipids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008853:Microscopy; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D018087:Plastids / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D005231:Fatty Acids, Unsaturated; D008563:Membrane Lipids; D026901:Membrane Transport Proteins; C475468:TGD1 protein, Arabidopsis; C534346:TGD4 protein, Arabidopsis; D044943:Fatty Acid Desaturases; C040448:delta-12 fatty acid desaturase; D000251:Adenosine Triphosphatases; C525795:TGD3 protein, Arabidopsis