title: Effect of single amino acid substitution on oxidative modifications of the Parkinson's disease-related protein, DJ-1.
abstract: Mutations in the gene encoding DJ-1 have been identified in patients with familial Parkinson's disease (PD) and are thought to inactivate a neuroprotective function. Oxidation of the sulfhydryl group to a sulfinic acid on cysteine residue C106 of DJ-1 yields the "2O " form, a variant of the protein with enhanced neuroprotective function. We hypothesized that some familial mutations disrupt DJ-1 activity by interfering with conversion of the protein to the 2O form. To address this hypothesis, we developed a novel quantitative mass spectrometry approach to measure relative changes in oxidation at specific sites in mutant DJ-1 as compared with the wild-type protein. Treatment of recombinant wild-type DJ-1 with a 10-fold molar excess of H(2)O(2) resulted in a robust oxidation of C106 to the sulfinic acid, whereas this modification was not detected in a sample of the familial PD mutant M26I exposed to identical conditions. Methionine oxidized isoforms of wild-type DJ-1 were depleted, presumably as a result of misfolding and aggregation, under conditions that normally promote conversion of the protein to the 2O form. These data suggest that the M26I familial substitution and methionine oxidation characteristic of sporadic PD may disrupt DJ-1 function by disfavoring a site-specific modification required for optimal neuroprotective activity. Our findings indicate that a single amino acid substitution can markedly alter a protein's ability to undergo oxidative modification, and they imply that stimulating the conversion of DJ-1 to the 2O form may be therapeutically beneficial in familial or sporadic PD.
authors: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
authors: Ashraf G
authors: AG
authors: Madian
authors: Jagadish
authors: J
authors: Hindupur
authors: John D
authors: JD
authors: Hulleman
authors: Naomi
authors: N
authors: Diaz-Maldonado
authors: Vartika R
authors: VR
authors: Mishra
authors: Emmanuel
authors: E
authors: Guigard
authors: Cyril M
authors: CM
authors: Kay
authors: Jean-Christophe
authors: JC
authors: Rochet
authors: Fred E
authors: FE
authors: Regnier
mesh_terms: D019943:Amino Acid Substitution; D003545:Cysteine / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008715:Methionine / Q000737:chemistry / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D015513:Oncogene Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000378:metabolism; D000071617:Protein Deglycase DJ-1; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013441:Sulfinic Acids / Q000378:metabolism*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D015513:Oncogene Proteins; D016877:Oxidants; D010446:Peptide Fragments; D013441:Sulfinic Acids; D008715:Methionine; D006861:Hydrogen Peroxide; C105131:PARK7 protein, human; D000071617:Protein Deglycase DJ-1; D003545:Cysteine