Title

Inactivation and Reactivation of the Mitochondrial alpha-Ketoglutarate Dehydrogenase Complex

Authors

Authors

Q. L. Shi; H. Xu; H. Q. Yu; N. W. Zhang; Y. Z. Ye; A. G. Estevez; H. T. Deng;G. E. Gibson

Comments

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Abbreviated Journal Title

J. Biol. Chem.

Keywords

PROTEIN-TYROSINE NITRATION; PEROXYNITRITE-TREATED PROTEINS; PROGRESSIVE; SUPRANUCLEAR PALSY; DEPENDENT ENZYME CHANGES; LUNG EPITHELIAL-CELLS; ALZHEIMERS-DISEASE; OXIDATIVE STRESS; HYDROGEN-PEROXIDE; GLUTATHIONE; METABOLISM; MULTIENZYME COMPLEXES; Biochemistry & Molecular Biology

Abstract

Reduced brain metabolism is an invariant feature of Alzheimer Disease (AD) that is highly correlated to the decline in brain functions. Decreased activities of key tricarboxylic acid cycle (TCA) cycle enzymes may underlie this abnormality and are highly correlated to the clinical state of the patient. The activity of the alpha-ketoglutarate dehydrogenase complex (KGDHC), an arguably rate-limiting enzyme of the TCA cycle, declines with AD, but the mechanism of inactivation and whether it can be reversed remains unknown. KGDHC consists of multiple copies of three subunits. KGDHC is sensitive to oxidative stress, which is pervasive in AD brain. The present studies tested the mechanism for the peroxynitrite-induced inactivation and subsequent reactivation of purified and cellular KGDHC. Peroxynitrite inhibited purified KGDHC activity in a dose-dependent manner and reduced subunit immunoreactivity and increased nitrotyrosine immunoreactivity. Nano-LC-MS/MS showed that the inactivation was related to nitration of specific tyrosine residues in the three subunits. GSH diminished the nitrotyrosine immunoreactivity of peroxynitrite-treated KGDHC, restored the activity and the immunoreactivity for KGDHC. Nano-LC-MS/MS showed this was related to de-nitration of specific tyrosine residues, suggesting KGDHC may have a denitrase activity. Treatment of N2a cells with peroxynitrite for 5 min followed by recovery of cells for 24 h reduced KGDHC activity and increased nitrotyrosine immunoreactivity. Increasing cellular GSH in peroxynitrite-treated cells rescued KGDHC activity to the control level. The results suggest that restoring KGDHC activity is possible and may be a useful therapeutic approach in neurodegenerative diseases.

Journal Title

Journal of Biological Chemistry

Volume

286

Issue/Number

20

Publication Date

1-1-2011

Document Type

Article

Language

English

First Page

17640

Last Page

17648

WOS Identifier

WOS:000290585200027

ISSN

0021-9258

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