title: Mitochondrial targeting of the human peptide methionine sulfoxide reductase (MSRA), an enzyme involved in the repair of oxidized proteins.
abstract: Peptide methionine sulfoxide reductase (MSRA) catalyzes the reduction of methionine sulfoxide to methionine. This widely expressed enzyme constitutes an important repair mechanism for oxidatively damaged proteins, which accumulate during the manifestation of certain degenerative diseases and aging processes. In addition, it is discussed to be involved in regulatory processes. Here we address the question of how the enzyme's diverse functions are reflected in its subcellular localization. Using fusions of the human version of MSRA with the enhanced green fluorescence protein expressed in various mammalian cell lines, we show a distinct localization at mitochondria. The N-terminal 23 amino acid residues contain the signal for this mitochondrial targeting. Activity tests showed that they are not required for enzyme function. Mitochondrial localization of native MSRA in mouse and rat liver slices was verified with an MSRA-specific antibody by using immunohistochemical methods. The protein was located in the mitochondrial matrix, as demonstrated by using pre-embedding immunostaining and electron microscopy. Mitochondria are the major source of reactive oxygen species (ROS). Therefore, MSRA has to be considered an important means for the general reduction of ROS release from mitochondria.
authors.affiliation: Molecular and Cellular Biophysics, Medical Faculty of the Friedrich Schiller University Jena, D-07747 Jena, Germany.
authors.forename: Alfred
authors.initials: A
authors.lastname: Hansel
authors.forename: Lioba
authors.initials: L
authors.lastname: Kuschel
authors.forename: Solveig
authors.initials: S
authors.lastname: Hehl
authors.forename: Cornelius
authors.initials: C
authors.lastname: Lemke
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Agricola
authors.forename: Toshinori
authors.initials: T
authors.lastname: Hoshi
authors.forename: Stefan H
authors.initials: SH
authors.lastname: Heinemann
mesh_terms: D016475:3T3 Cells; D000409:Alanine / Q000235:genetics; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001692:Biological Transport; D016466:CHO Cells; D002417:Cattle; D002460:Cell Line; D006224:Cricetinae; D049452:Green Fluorescent Proteins; D006801:Humans; D007150:Immunohistochemistry; D019169:Jurkat Cells; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051150:Methionine Sulfoxide Reductases; D051379:Mice; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D021382:Protein Sorting Signals / Q000235:genetics; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D008164:Luminescent Proteins; D021382:Protein Sorting Signals; D011506:Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D010088:Oxidoreductases; D051150:Methionine Sulfoxide Reductases; C027219:methionine sulfoxide reductase; D000409:Alanine