title: In vitro oxidative inactivation of human presequence protease (hPreP).
abstract: The mitochondrial peptidasome called presequence protease (PreP) is responsible for the degradation of presequences and other unstructured peptides including the amyloid-β peptide, whose accumulation may have deleterious effects on mitochondrial function. Recent studies showed that PreP activity is reduced in Alzheimer disease (AD) patients and AD mouse models compared to controls, which correlated with an enhanced reactive oxygen species production in mitochondria. In this study, we have investigated the effects of a biologically relevant oxidant, hydrogen peroxide (H(2)O(2)), on the activity of recombinant human PreP (hPreP). H(2)O(2) inhibited hPreP activity in a concentration-dependent manner, resulting in oxidation of amino acid residues (detected by carbonylation) and lowered protein stability. Substitution of the evolutionarily conserved methionine 206 for leucine resulted in increased sensitivity of hPreP to oxidation, indicating a possible protective role of M206 as internal antioxidant. The activity of hPreP oxidized at low concentrations of H(2)O(2) could be restored by methionine sulfoxide reductase A (MsrA), an enzyme that localizes to the mitochondrial matrix, suggesting that hPreP constitutes a substrate for MsrA. In summary, our in vitro results suggest a possible redox control of hPreP in the mitochondrial matrix and support the protective role of the conserved methionine 206 residue as an internal antioxidant.
authors.affiliation: Arrhenius Laboratories for Natural Sciences, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden. pedro@dbb.su.se
authors.forename: Pedro Filipe
authors.initials: PF
authors.lastname: Teixeira
authors.forename: Catarina Moreira
authors.initials: CM
authors.lastname: Pinho
authors.forename: Rui M
authors.initials: RM
authors.lastname: Branca
authors.forename: Janne
authors.initials: J
authors.lastname: Lehtiö
authors.forename: Rodney L
authors.initials: RL
authors.lastname: Levine
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Glaser
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D020134:Catalytic Domain; D017124:Conserved Sequence; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007700:Kinetics; D051150:Methionine Sulfoxide Reductases / Q000737:chemistry; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry; D059748:Proteolysis; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000235:genetics
chemical_list: D024101:Mitochondrial Proteins; D016877:Oxidants; D010446:Peptide Fragments; D006861:Hydrogen Peroxide; D051150:Methionine Sulfoxide Reductases; C027219:methionine sulfoxide reductase; C514899:PREP protein, human; D012697:Serine Endopeptidases