title: Ascorbate peroxidase-thioredoxin interaction.
abstract: Proteomics data have suggested ascorbate peroxidase (APX) to be a potential thioredoxin-interacting protein. Using recombinant enzymes, we observed that incubation of pea cytosolic APX with reduced poplar thioredoxins h drastically inactivated the peroxidase. A similar inactivation is induced by reduced glutathione and dithiothreitol, whereas diamide and oxidized glutathione have no effect. Oxygen consumption measurements, modifications of the APX visible spectrum and protection by hydrogen peroxide scavenging enzymes suggest that APX oxidizes thiols leading to the generation of thiyl radicals. These radicals can in turn react with thiyl anions to produce the disulfide radical anions, which are responsible for oxygen reduction and subsequent hydrogen peroxide production. The APX inactivation is not due solely to hydrogen peroxide since fluorimetry indicates that the environment of the APX tryptophan residues is dramatically modified only in the presence of thiol groups. The physiological implications of this interaction are discussed.
authors.affiliation: Unité Mixte de Recherches 1136 INRA UHP (Interaction Arbres Microorganismes), IFR 110 Génomique Ecophysiologie et Ecologie Fonctionnelles, Faculté des Sciences, Nancy Université, BP 239, 54506, Vandoeuvre-lès-Nancy Cedex, France. gelhaye@lcb.uhp-nancy.fr
authors.forename: Eric
authors.initials: E
authors.lastname: Gelhaye
authors.forename: Nicolas
authors.initials: N
authors.lastname: Navrot
authors.forename: Isabel K
authors.initials: IK
authors.lastname: Macdonald
authors.forename: Nicolas
authors.initials: N
authors.lastname: Rouhier
authors.forename: Emma Lloyd
authors.initials: EL
authors.lastname: Raven
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Jacquot
mesh_terms: D017360:Arabidopsis / Q000201:enzymology; D060387:Ascorbate Peroxidases; D004229:Dithiothreitol / Q000378:metabolism; D005453:Fluorescence; D005978:Glutathione / Q000378:metabolism; D010101:Oxygen Consumption; D018532:Pisum sativum / Q000201:enzymology; D010544:Peroxidases / Q000378:metabolism*; D013880:Thioredoxin-Disulfide Reductase / Q000235:genetics / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: D013879:Thioredoxins; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D013880:Thioredoxin-Disulfide Reductase; D005978:Glutathione; D004229:Dithiothreitol