1. Mitochondrial targeting of the human peptide methionine sulfoxide reductase (MSRA), an enzyme involved in the repair of oxidized proteins.
- Author
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Hansel A, Kuschel L, Hehl S, Lemke C, Agricola HJ, Hoshi T, and Heinemann SH
- Subjects
- 3T3 Cells, Alanine genetics, Amino Acid Sequence, Amino Acid Substitution, Animals, Biological Transport, CHO Cells, Cattle, Cell Line, Cricetinae, Green Fluorescent Proteins, Humans, Immunohistochemistry, Jurkat Cells, Luminescent Proteins genetics, Luminescent Proteins metabolism, Methionine Sulfoxide Reductases, Mice, Microscopy, Confocal, Microscopy, Fluorescence, Mitochondria, Liver enzymology, Molecular Sequence Data, Oxidation-Reduction, Oxidoreductases genetics, Protein Sorting Signals genetics, Rats, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins metabolism, Sequence Homology, Amino Acid, Transfection, Tumor Cells, Cultured, Mitochondria enzymology, Oxidoreductases metabolism, Proteins metabolism
- 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.
- Published
- 2002
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