title: Endogenous 3,4-dihydroxyphenylalanine and dopaquinone modifications on protein tyrosine: links to mitochondrially derived oxidative stress via hydroxyl radical.
abstract: Oxidative modifications of protein tyrosines have been implicated in multiple human diseases. Among these modifications, elevations in levels of 3,4-dihydroxyphenylalanine (DOPA), a major product of hydroxyl radical addition to tyrosine, has been observed in a number of pathologies. Here we report the first proteome survey of endogenous site-specific modifications, i.e. DOPA and its further oxidation product dopaquinone in mouse brain and heart tissues. Results from LC-MS/MS analyses included 50 and 14 DOPA-modified tyrosine sites identified from brain and heart, respectively, whereas only a few nitrotyrosine-containing peptides, a more commonly studied marker of oxidative stress, were detectable, suggesting the much higher abundance for DOPA modification as compared with tyrosine nitration. Moreover, 20 and 12 dopaquinone-modified peptides were observed from brain and heart, respectively; nearly one-fourth of these peptides were also observed with DOPA modification on the same sites. For both tissues, these modifications are preferentially found in mitochondrial proteins with metal binding properties, consistent with metal-catalyzed hydroxyl radical formation from mitochondrial superoxide and hydrogen peroxide. These modifications also link to a number of mitochondrially associated and other signaling pathways. Furthermore, many of the modification sites were common sites of previously reported tyrosine phosphorylation, suggesting potential disruption of signaling pathways. Collectively, the results suggest that these modifications are linked with mitochondrially derived oxidative stress and may serve as sensitive markers for disease pathologies.
authors.affiliation: Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Monroe
authors.forename: Baowei
authors.initials: B
authors.lastname: Chen
authors.forename: Mark H
authors.initials: MH
authors.lastname: Chin
authors.forename: Tyler H
authors.initials: TH
authors.lastname: Heibeck
authors.forename: Athena A
authors.initials: AA
authors.lastname: Schepmoes
authors.forename: Feng
authors.initials: F
authors.lastname: Yang
authors.forename: Brianne O
authors.initials: BO
authors.lastname: Petritis
authors.forename: David G
authors.initials: DG
authors.lastname: Camp
authors.forename: Joel G
authors.initials: JG
authors.lastname: Pounds
authors.forename: Jon M
authors.initials: JM
authors.lastname: Jacobs
authors.forename: Desmond J
authors.initials: DJ
authors.lastname: Smith
authors.forename: Diana J
authors.initials: DJ
authors.lastname: Bigelow
authors.forename: Richard D
authors.initials: RD
authors.lastname: Smith
authors.forename: Wei-Jun
authors.initials: WJ
authors.lastname: Qian
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D016227:Benzoquinones / Q000737:chemistry / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism*; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism; D009928:Organ Specificity; D018384:Oxidative Stress; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; D016227:Benzoquinones; D003598:Cytoskeletal Proteins; D024101:Mitochondrial Proteins; D010455:Peptides; D017665:Hydroxyl Radical; D014443:Tyrosine; D004295:Dihydroxyphenylalanine; C035157:dopaquinone