title: From endoplasmic reticulum to mitochondria: absence of the Arabidopsis ATP antiporter endoplasmic Reticulum Adenylate Transporter1 perturbs photorespiration.
abstract: The carrier Endoplasmic Reticulum Adenylate Transporter1 (ER-ANT1) resides in the endoplasmic reticulum (ER) membrane and acts as an ATP/ADP antiporter. Mutant plants lacking ER-ANT1 exhibit a dwarf phenotype and their seeds contain reduced protein and lipid contents. In this study, we describe a further surprising metabolic peculiarity of the er-ant1 mutants. Interestingly, Gly levels in leaves are immensely enhanced (26×) when compared with that of wild-type plants. Gly accumulation is caused by significantly decreased mitochondrial glycine decarboxylase (GDC) activity. Reduced GDC activity in mutant plants was attributed to oxidative posttranslational protein modification induced by elevated levels of reactive oxygen species (ROS). GDC activity is crucial for photorespiration; accordingly, morphological and physiological defects in er-ant1 plants were nearly completely abolished by application of high environmental CO(2) concentrations. The latter observation demonstrates that the absence of ER-ANT1 activity mainly affects photorespiration (maybe solely GDC), whereas basic cellular metabolism remains largely unchanged. Since ER-ANT1 homologs are restricted to higher plants, it is tempting to speculate that this carrier fulfils a plant-specific function directly or indirectly controlling cellular ROS production. The observation that ER-ANT1 activity is associated with cellular ROS levels reveals an unexpected and critical physiological connection between the ER and other organelles in plants.
authors.affiliation: Department of Plant Physiology, University of Kaiserslautern, D-67663 Kaiserslautern, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Hoffmann
authors.forename: Bartolome
authors.initials: B
authors.lastname: Plocharski
authors.forename: Ilka
authors.initials: I
authors.lastname: Haferkamp
authors.forename: Michaela
authors.initials: M
authors.lastname: Leroch
authors.forename: Ralph
authors.initials: R
authors.lastname: Ewald
authors.forename: Hermann
authors.initials: H
authors.lastname: Bauwe
authors.forename: Jan
authors.initials: J
authors.lastname: Riemer
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Herrmann
authors.forename: H Ekkehard
authors.initials: HE
authors.lastname: Neuhaus
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D017920:Antiporters / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D015870:Gene Expression / Q000528:radiation effects; D005998:Glycine / Q000187:drug effects; D050841:Glycine Dehydrogenase (Decarboxylating) / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010101:Oxygen Consumption / Q000235:genetics / Q000528:radiation effects; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D017920:Antiporters; D029681:Arabidopsis Proteins; C587206:ER-ANT1 protein, Arabidopsis; D024101:Mitochondrial Proteins; D000255:Adenosine Triphosphate; D050841:Glycine Dehydrogenase (Decarboxylating); D005998:Glycine