Examination of the Reaction of Fully Reduced Cytochrome Oxidase with Hydrogen Peroxide by Flow-Flash Spectroscopy†

ABSTRACT Cox11p is an integral protein of the inner mitochondrial membrane that is essential for cytochrome c oxidase assembly. The bulk of the protein is located in the intermembrane space and displays high levels of evolutionary conservation. We have analyzed a collection of site-directed and random cox11 mutants in an effort to further define essential portions of the molecule. Of the alleles studied, more than half had no apparent effect on Cox11p function. Among the respiration deficiency-encoding alleles, we identified three distinct phenotypes, which included a set of mutants with a misassembled or partially assembled cytochrome oxidase, as indicated by a blue-shifted cytochrome aa 3 peak. In addition to the shifted spectral signal, these mutants also display a specific reduction in the levels of subunit 1 (Cox1p). Two of these mutations are likely to occlude a surface pocket behind the copper-binding domain in Cox11p, based on analogy with the Sinorhizobium meliloti Cox11 solution structure, thereby suggesting that this pocket is crucial for Cox11p function. Sequential deletions of the matrix portion of Cox11p suggest that this domain is not functional beyond the residues involved in mitochondrial targeting and membrane insertion. In addition, our studies indicate that Δcox11, like Δsco1, displays a specific hypersensitivity to hydrogen peroxide. Our studies provide the first evidence at the level of the cytochrome oxidase holoenzyme that Cox1p is the in vivo target for Cox11p and suggest that Cox11p may also have a role in the response to hydrogen peroxide exposure.

Download Full-text

Cytochrome oxidase and its derivatives. VII. Further observations on the compound formed by the reaction of ferrous cytochrome c oxidase with oxygen and hydrogen peroxide and on its reactions

Biochimica et Biophysica Acta (BBA) - Bioenergetics ◽

10.1016/0005-2728(67)90107-7 ◽

1967 ◽

Vol 143 (1) ◽

pp. 37-51 ◽

Cited By ~ 19

Author(s):

R. Lemberg ◽

J. Stanbury

Keyword(s):

Hydrogen Peroxide ◽

Cytochrome C ◽

Cytochrome Oxidase ◽

Cytochrome C Oxidase

Download Full-text

Nonparticipation of hydrogen peroxide in the cytochrome oxidase reaction

Archives of Biochemistry and Biophysics ◽

10.1016/0003-9861(65)90033-0 ◽

1965 ◽

Vol 112 (1) ◽

pp. 209-211 ◽

Cited By ~ 4

Author(s):

Alvin I. Krasna

Keyword(s):

Hydrogen Peroxide ◽

Cytochrome Oxidase ◽

Oxidase Reaction

Download Full-text

Aging, cytochrome oxidase activity, and hydrogen peroxide release by mitochondria

Free Radical Biology and Medicine ◽

10.1016/0891-5849(93)90139-l ◽

1993 ◽

Vol 14 (6) ◽

pp. 583-588 ◽

Cited By ~ 106

Author(s):

Rajindar S. Sohal

Keyword(s):

Hydrogen Peroxide ◽

Cytochrome Oxidase ◽

Oxidase Activity ◽

Cytochrome Oxidase Activity ◽

Hydrogen Peroxide Release

Download Full-text

Nitric oxide, cytochrome c and mitochondria

Biochemical Society Symposium ◽

10.1042/bss0660017 ◽

1999 ◽

Vol 66 ◽

pp. 17-25 ◽

Cited By ~ 135

Author(s):

Guy C. Brown ◽

Vilmante Borutaite

Keyword(s):

Nitric Oxide ◽

Hydrogen Peroxide ◽

Cytochrome C ◽

Cytochrome Oxidase ◽

Protease Activity ◽

Complex I ◽

Glutamate Release ◽

Nerve Terminals ◽

No Inhibition ◽

Brain Nerve Terminals

Nitric oxide (NO) and its derivative, peroxynitrite (ONOO-), inhibit mitochondrial respiration, and this inhibition may contribute to both the physiological and cytotoxic actions of NO. Nanomolar concentrations of NO rapidly and reversibly inhibited cytochrome oxidase in competition with oxygen, as shown with isolated cytochrome oxidase, mitochondria, brain nerve terminals and cells. Cultured astrocytes and macrophages activated (by cytokines and endotoxin) to express the inducible form of NO synthase produced up to 1 μM NO, and inhibited their own respiration and that of co-incubated cells via reversible NO inhibition of cytochrome oxidase. NO-induced inhibition of respiration in brain nerve terminals resulted in rapid glutamate release, which might contribute to the neurotoxicity of NO. NO inhibition of cytochrome oxidase is reversible; however, incubation of cells with NO donors for 4 hours resulted in an inhibition of complex I, which was reversible by light and thiol reagents and may be due to nitrosylation of thiols in complex I. NO also caused the acute inhibition of catalase, stimulation of hydrogen peroxide production by mitochondria, and reaction with hydrogen peroxide on superoxide dismutase to produce peroxynitrite. Peroxynitrite inhibited complexes I, II and V (the ATP synthase), aconitase, creatine kinase, and increases the proton leak in isolated mitochondria. Peroxynitrite also caused opening of the permeability transition pore, resulting in the release of cytochrome c, which might then trigger apoptosis. Hypoxia/ischaemia also resulted in an acute reversible inhibition of cytochrome oxidase. Heart ischaemia caused the release of cytochrome c from mitochondria into the cytosol, and at the same time caspase-3-like-protease activity was activated in the cytoplasm. Addition of cytochrome c to non-ischaemic cytosol also caused activation of this protease activity, suggesting that caspase activation and consequent apoptosis is at least partly a result of this cytochrome c release.

Download Full-text