期刊
BIOCHEMISTRY
卷 45, 期 20, 页码 6392-6406出版社
AMER CHEMICAL SOC
DOI: 10.1021/bi060502a
关键词
-
资金
- NCRR NIH HHS [P41-RR00954, P41 RR000954-30, P41 RR000954] Funding Source: Medline
- NHLBI NIH HHS [P01 HL057278, P01-HL57278] Funding Source: Medline
- NIDDK NIH HHS [P30 DK056341-05S2, P30-DK56341, P60 DK020579, P60 DK020579-269005, P30 DK056341-06, R37-DK34388, R37 DK034388-23, R37 DK034388, P60-DK20579, P30 DK056341, P30 DK056341-069003] Funding Source: Medline
- NIGMS NIH HHS [P41 GM103422] Funding Source: Medline
- PHS HHS [R01-69455] Funding Source: Medline
Group VIA phospholipase A(2)(iPLA(2)beta) is expressed in phagocytes, vascular cells, pancreatic islet beta-cells, neurons, and other cells and plays roles in transcriptional regulation, cell proliferation, apoptosis, secretion, and other events. A bromoenol lactone (BEL) suicide substrate used to study iPLA(2)beta functions inactivates iPLA(2)beta by alkylating Cys thiols. Because thiol redox reactions are important in signaling and some cells that express iPLA(2)beta produce biological oxidants, iPLA(2)beta might be subject to redox regulation. We report that biological concentrations of H2O2, NO, and HOCl inactivate iPLA(2)beta, and this can be partially reversed by dithiothreitol (DTT). Oxidant-treated iPLA(2)beta modifications were studied by LCMS/MS analyses of tryptic digests and included DTT-reversible events, e.g., formation of disulfide bonds and sulfenic acids, and others not so reversed, e. g., formation of sulfonic acids, Trp oxides, and Met sulfoxides. W-460 oxidation could cause irreversible inactivation because it is near the lipase consensus sequence ((463)GTSTG(467)), and site-directed mutagenesis of W-460 yields active mutant enzymes that exhibit no DTT- irreversible oxidative inactivation. Cys651-sulfenic acid formation could be one DTT-reversible inactivation event because Cys651 modification correlates closely with activity loss and its mutagenesis reduces sensitivity to inhibition. Intermolecular disulfide bond formation might also cause reversible inactivation because oxidant-treated iPLA(2)beta contains DTT-reducible oligomers, and oligomerization occurs with time- and temperature-dependent iPLA(2)beta inactivation that is attenuated by DTT or ATP. Subjecting insulinoma cells to oxidative stress induces iPLA(2)beta oligomerization, loss of activity, and subcellular redistribution and reduces the rate of release of arachidonate from phospholipids. These findings raise the possibility that redox reactions affect iPLA(2)beta functions.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据