期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 285, 期 5, 页码 3168-3180出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M109.056846
关键词
-
资金
- National Institutes of Health [HL83237, HL63744]
Complex I (NQR) is a critical site of superoxide (O-2(radical anion)) production and the major host of redox protein thiols in mitochondria. In response to oxidative stress, NQR-derived protein thiols at the 51- and 75-kDa subunits are known to be reversibly S-glutathionylated. Although several glutathionylated domains from NQR 51 and 75 kDa have been identified, their roles in the regulatory functions remain to be explored. To gain further insights into protein S-glutathionylation of complex I, we used two peptides of S-glutathionylated domain ((200)GAGAYI (C) under bar GEETALIESIEGK(219) of 51-kDa protein and (VDSDTL)-V-361 (C) under bar TEEVFPTAGAGTDLR(382) of 75-kDa protein) as chimeric epitopes incorporating a promiscuous T-cell epitope to generate two polyclonal antibodies, AbGSCA206 and AbGSCB367. Binding of AbGSCA206 and AbGSCB367 inhibited NQR-mediated O-2(radical anion). generation by 37 and 57%, as measured by EPR spin-trapping. To further provide an appropriate control, two peptides of non-glutathionylated domain ((21)SGDTTAPKKTSFGSLKDFDR(40) of 51-kDa peptide and (100)WNILTNSEKTKKAREGVMEFL(120) of 75-kDa peptide) were synthesized as chimeric epitopes to generate two polyclonal antibodies, Ab51 and Ab75. Binding of A51 did not affect NQR-mediated O-2(radical anion) generation to a significant level. However, binding of Ab75 inhibited NQR- mediated O-2(radical anion) generation by 35%. None of AbGSCA206, AbGSCB367, Ab51, or Ab75 showed an inhibitory effect on the electron transfer activity of NQR, suggesting that antibody binding to the glutathione-binding domain decreased electron leakage from the hydrophilic domain of NQR. When heart tissue homogenates were immunoprecipitated with Ab51 or Ab75 and probed with an antibody against glutathione, protein S-glutathionylation was enhanced in post-ischemic myocardium at the NQR 51-kDa subunit, but not at the 75-kDa subunit, indicating that the 51-kDa subunit of flavin subcomplex is more sensitive to oxidative stress resulting from myocardial infarction.
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