title: A RAD52-like single-stranded DNA binding protein affects mitochondrial DNA repair by recombination.
abstract: The plant mitochondrial DNA-binding protein ODB1 was identified from a mitochondrial extract after DNA-affinity purification. ODB1 (organellar DNA-binding protein 1) co-purified with WHY2, a mitochondrial member of the WHIRLY family of plant-specific proteins involved in the repair of organellar DNA. The Arabidopsis thaliana ODB1 gene is identical to RAD52-1, which encodes a protein functioning in homologous recombination in the nucleus but additionally localizing to mitochondria. We confirmed the mitochondrial localization of ODB1 by in vitro and in vivo import assays, as well as by immunodetection on Arabidopsis subcellular fractions. In mitochondria, WHY2 and ODB1 were found in large nucleo-protein complexes. Both proteins co-immunoprecipitated in a DNA-dependent manner. In vitro assays confirmed DNA binding by ODB1 and showed that the protein has higher affinity for single-stranded than for double-stranded DNA. ODB1 showed no sequence specificity in vitro. In vivo, DNA co-immunoprecipitation indicated that ODB1 binds sequences throughout the mitochondrial genome. ODB1 promoted annealing of complementary DNA sequences, suggesting a RAD52-like function as a recombination mediator. Arabidopsis odb1 mutants were morphologically indistinguishable from the wild-type, but following DNA damage by genotoxic stress, they showed reduced mitochondrial homologous recombination activity. Under the same conditions, the odb1 mutants showed an increase in illegitimate repair bypasses generated by microhomology-mediated recombination. These observations identify ODB1 as a further component of homologous recombination-dependent DNA repair in plant mitochondria.
authors: Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg Cedex, France.
authors: Sabina
authors: S
authors: Janicka
authors: Kristina
authors: K
authors: Kühn
authors: Monique
authors: M
authors: Le Ret
authors: Geraldine
authors: G
authors: Bonnard
authors: Patrice
authors: P
authors: Imbault
authors: Halina
authors: H
authors: Augustyniak
authors: José M
authors: JM
authors: Gualberto
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001937:Brassica / Q000235:genetics* / Q000378:metabolism; D002846:Chromatography, Affinity; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D004260:DNA Repair; D004272:DNA, Mitochondrial / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D059765:Homologous Recombination; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009928:Organ Specificity; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D051721:Rad52 DNA Repair and Recombination Protein / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004272:DNA, Mitochondrial; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; C579794:ODB1 protein, Arabidopsis; D010940:Plant Proteins; D051721:Rad52 DNA Repair and Recombination Protein; C503334:Whirly2 protein, Arabidopsis