Modulation of mitochondrial complex I activity by reversible Ca 2+ and NADH mediated superoxide anion dependent inhibition

Hesham A. Sadek, Pamela A. Szweda, Luke I. Szweda

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Complex I, a key component of the mitochondrial respiratory chain, exhibits diminished activity as a result of cardiac ischemia/reperfusion. Cardiac ischemia/reperfusion is associated with increases in the levels of mitochondrial Ca2+ and pro-oxidants. In the current in vitro study, we sought evidence for a mechanistic link between Ca2+, pro-oxidants, and inhibition of complex I utilizing mitochondria isolated from rat heart. Our results indicate that addition of Ca2+ to solubilized mitochondria results in loss in complex I activity. Ca2+ induced a maximum decrease in complex I activity of approximately 35% at low micromolar concentrations over a narrow physiologically relevant pH range. Loss in activity required reducing equivalents in the form of NADH and was not reversed upon addition of EGTA. The antioxidants N-acetylcysteine and superoxide dismutase, but not catalase, prevented inhibition, indicating the involvement of superoxide anion (O2•-) in the inactivation process. Importantly, the sulfhydryl reducing agent DTT was capable of fully restoring complex I activity implicating the formation of sulfenic acid and/or disulfide derivatives of cysteine in the inactivation process. Finally, complex I can reactivate endogenously upon Ca2+ removal if NADH is present and the enzyme is allowed to turnover catalytically. Thus, the present study provides a mechanistic link between three alterations known to occur during cardiac ischemia/reperfusion, mitochondrial Ca2+ accumulation, free radical production, and complex I inhibition. The reversibility of these processes suggests redox regulation of Ca2+ handling.

Original languageEnglish (US)
Pages (from-to)8494-8502
Number of pages9
JournalBiochemistry
Volume43
Issue number26
DOIs
StatePublished - Jul 6 2004

Fingerprint

Mitochondria
Superoxides
NAD
Reperfusion
Reactive Oxygen Species
Sulfenic Acids
Ischemia
Modulation
Egtazic Acid
Reducing Agents
Acetylcysteine
Disulfides
Catalase
Superoxide Dismutase
Free Radicals
Cysteine
Rats
Antioxidants
Electron Transport
Derivatives

ASJC Scopus subject areas

  • Biochemistry

Cite this

Modulation of mitochondrial complex I activity by reversible Ca 2+ and NADH mediated superoxide anion dependent inhibition. / Sadek, Hesham A.; Szweda, Pamela A.; Szweda, Luke I.

In: Biochemistry, Vol. 43, No. 26, 06.07.2004, p. 8494-8502.

Research output: Contribution to journalArticle

@article{aa47746fa1df4ef8b58385bc7e905283,
title = "Modulation of mitochondrial complex I activity by reversible Ca 2+ and NADH mediated superoxide anion dependent inhibition",
abstract = "Complex I, a key component of the mitochondrial respiratory chain, exhibits diminished activity as a result of cardiac ischemia/reperfusion. Cardiac ischemia/reperfusion is associated with increases in the levels of mitochondrial Ca2+ and pro-oxidants. In the current in vitro study, we sought evidence for a mechanistic link between Ca2+, pro-oxidants, and inhibition of complex I utilizing mitochondria isolated from rat heart. Our results indicate that addition of Ca2+ to solubilized mitochondria results in loss in complex I activity. Ca2+ induced a maximum decrease in complex I activity of approximately 35{\%} at low micromolar concentrations over a narrow physiologically relevant pH range. Loss in activity required reducing equivalents in the form of NADH and was not reversed upon addition of EGTA. The antioxidants N-acetylcysteine and superoxide dismutase, but not catalase, prevented inhibition, indicating the involvement of superoxide anion (O2•-) in the inactivation process. Importantly, the sulfhydryl reducing agent DTT was capable of fully restoring complex I activity implicating the formation of sulfenic acid and/or disulfide derivatives of cysteine in the inactivation process. Finally, complex I can reactivate endogenously upon Ca2+ removal if NADH is present and the enzyme is allowed to turnover catalytically. Thus, the present study provides a mechanistic link between three alterations known to occur during cardiac ischemia/reperfusion, mitochondrial Ca2+ accumulation, free radical production, and complex I inhibition. The reversibility of these processes suggests redox regulation of Ca2+ handling.",
author = "Sadek, {Hesham A.} and Szweda, {Pamela A.} and Szweda, {Luke I.}",
year = "2004",
month = "7",
day = "6",
doi = "10.1021/bi049803f",
language = "English (US)",
volume = "43",
pages = "8494--8502",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "26",

}

TY - JOUR

T1 - Modulation of mitochondrial complex I activity by reversible Ca 2+ and NADH mediated superoxide anion dependent inhibition

AU - Sadek, Hesham A.

AU - Szweda, Pamela A.

AU - Szweda, Luke I.

PY - 2004/7/6

Y1 - 2004/7/6

N2 - Complex I, a key component of the mitochondrial respiratory chain, exhibits diminished activity as a result of cardiac ischemia/reperfusion. Cardiac ischemia/reperfusion is associated with increases in the levels of mitochondrial Ca2+ and pro-oxidants. In the current in vitro study, we sought evidence for a mechanistic link between Ca2+, pro-oxidants, and inhibition of complex I utilizing mitochondria isolated from rat heart. Our results indicate that addition of Ca2+ to solubilized mitochondria results in loss in complex I activity. Ca2+ induced a maximum decrease in complex I activity of approximately 35% at low micromolar concentrations over a narrow physiologically relevant pH range. Loss in activity required reducing equivalents in the form of NADH and was not reversed upon addition of EGTA. The antioxidants N-acetylcysteine and superoxide dismutase, but not catalase, prevented inhibition, indicating the involvement of superoxide anion (O2•-) in the inactivation process. Importantly, the sulfhydryl reducing agent DTT was capable of fully restoring complex I activity implicating the formation of sulfenic acid and/or disulfide derivatives of cysteine in the inactivation process. Finally, complex I can reactivate endogenously upon Ca2+ removal if NADH is present and the enzyme is allowed to turnover catalytically. Thus, the present study provides a mechanistic link between three alterations known to occur during cardiac ischemia/reperfusion, mitochondrial Ca2+ accumulation, free radical production, and complex I inhibition. The reversibility of these processes suggests redox regulation of Ca2+ handling.

AB - Complex I, a key component of the mitochondrial respiratory chain, exhibits diminished activity as a result of cardiac ischemia/reperfusion. Cardiac ischemia/reperfusion is associated with increases in the levels of mitochondrial Ca2+ and pro-oxidants. In the current in vitro study, we sought evidence for a mechanistic link between Ca2+, pro-oxidants, and inhibition of complex I utilizing mitochondria isolated from rat heart. Our results indicate that addition of Ca2+ to solubilized mitochondria results in loss in complex I activity. Ca2+ induced a maximum decrease in complex I activity of approximately 35% at low micromolar concentrations over a narrow physiologically relevant pH range. Loss in activity required reducing equivalents in the form of NADH and was not reversed upon addition of EGTA. The antioxidants N-acetylcysteine and superoxide dismutase, but not catalase, prevented inhibition, indicating the involvement of superoxide anion (O2•-) in the inactivation process. Importantly, the sulfhydryl reducing agent DTT was capable of fully restoring complex I activity implicating the formation of sulfenic acid and/or disulfide derivatives of cysteine in the inactivation process. Finally, complex I can reactivate endogenously upon Ca2+ removal if NADH is present and the enzyme is allowed to turnover catalytically. Thus, the present study provides a mechanistic link between three alterations known to occur during cardiac ischemia/reperfusion, mitochondrial Ca2+ accumulation, free radical production, and complex I inhibition. The reversibility of these processes suggests redox regulation of Ca2+ handling.

UR - http://www.scopus.com/inward/record.url?scp=3142616357&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=3142616357&partnerID=8YFLogxK

U2 - 10.1021/bi049803f

DO - 10.1021/bi049803f

M3 - Article

C2 - 15222760

AN - SCOPUS:3142616357

VL - 43

SP - 8494

EP - 8502

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 26

ER -