title: Identification of a novel adenine nucleotide transporter in the endoplasmic reticulum of Arabidopsis.
abstract: Many metabolic reactions in the endoplasmic reticulum (ER) require high levels of energy in the form of ATP, which is important for cell viability. Here, we report on an adenine nucleotide transporter residing in the ER membranes of Arabidopsis thaliana (ER-ANT1). Functional integration of ER-ANT1 in the cytoplasmic membrane of intact Escherichia coli cells reveals a high specificity for an ATP/ADP antiport. Immunodetection in transgenic ER-ANT1-C-MYC-tag Arabidopsis plants and immunogold labeling of wild-type pollen grain tissue using a peptide-specific antiserum reveal the localization of this carrier in ER membranes. Transgenic ER-ANT1-promoter-beta-glucuronidase Arabidopsis lines show high expression in ER-active tissues (i.e., pollen, seeds, root tips, apical meristems, or vascular bundles). Two independent ER-ANT1 Arabidopsis knockout lines indicate a high physiological relevance of ER-ANT1 for ATP transport into the plant ER (e.g., disruption of ER-ANT1 results in a drastic retardation of plant growth and impaired root and seed development). In these ER-ANT1 knockout lines, the expression levels of several genes encoding ER proteins that are dependent on a sufficient ATP supply (i.e., BiP [for luminal binding protein] chaperones, calreticulin chaperones, Ca2+-dependent protein kinase, and SEC61) are substantially decreased.
authors.affiliation: Pflanzenphysiologie, Technische Universität Kaiserslautern, D-67663 Kaiserslautern, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Leroch
authors.forename: H Ekkehard
authors.initials: HE
authors.lastname: Neuhaus
authors.forename: Simon
authors.initials: S
authors.lastname: Kirchberger
authors.forename: Sandra
authors.initials: S
authors.lastname: Zimmermann
authors.forename: Michael
authors.initials: M
authors.lastname: Melzer
authors.forename: Joachim
authors.initials: J
authors.lastname: Gerhold
authors.forename: Joachim
authors.initials: J
authors.lastname: Tjaden
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
chemical_list: D000227:Adenine Nucleotides; D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; D000255:Adenosine Triphosphate