scholarly journals A Cytochrome c Oxidase Model Catalyzes Oxygen to Water Reduction Under Rate-Limiting Electron Flux

Science ◽  
2007 ◽  
Vol 315 (5818) ◽  
pp. 1565-1568 ◽  
Author(s):  
J. P. Collman ◽  
N. K. Devaraj ◽  
R. A. Decreau ◽  
Y. Yang ◽  
Y.-L. Yan ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Electron Flux ◽  
Water Reduction ◽  
Rate Limiting

scholarly journals Metal-binding mechanism of Cox17, a copper chaperone for cytochrome c oxidase

2004 ◽  
Vol 382 (1) ◽  
pp. 307-314 ◽  
Author(s):  
Peep PALUMAA ◽  
Liina KANGUR ◽  
Anastassia VORONOVA ◽  
Rannar SILLARD
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Metal Binding ◽  
Copper Ions ◽  
Copper Chaperone ◽  
Copper Chaperones ◽  
Rate Limiting Step ◽  
Charge State Distributions ◽  
Rate Limiting ◽  
Partner Proteins

Cox17, a copper chaperone for cytochrome c oxidase, is an essential and highly conserved protein. The structure and mechanism of functioning of Cox17 are unknown, and even its metalbinding stoichiometry is elusive. In the present study, we demonstrate, using electrospray ionization–MS, that porcine Cox17 binds co-operatively four Cu+ ions. Cu4Cox17 is stable at pH values above 3 and fluorescence spectra indicate the presence of a solvent-shielded multinuclear Cu(I) cluster. Combining our results with earlier EXAFS results on yeast CuCox17, we suggest that Cu4Cox17 contains a Cu4S6-type cluster. At supramillimolar concentrations, dithiothreitol extracts metals from Cu4Cox17, and an apparent copper dissociation constant KCu=13 fM was calculated from these results. Charge-state distributions of different Cox17 forms suggest that binding of the first Cu+ ion to Cox17 causes a conformational change from an open to a compact state, which may be the rate-limiting step in the formation of Cu4Cox17. Cox17 binds non-co-operatively two Zn2+ ions, but does not bind Ag+ ions, which highlights its extremely high metal-binding specificity. We further demonstrate that porcine Cox17 can also exist in partly oxidized (two disulphide bridges) and fully oxidized (three disulphide bridges) forms. Partly oxidized Cox17 can bind one Cu+ or Zn2+ ion, whereas fully oxidized Cox17 does not bind metals. The metal-binding properties of Cox17 imply that, in contrast with other copper chaperones, Cox17 is designed for the simultaneous transfer of up to four copper ions to partner proteins. Metals can be released from Cox17 by non-oxidative as well as oxidative mechanisms.

Regulation of electron flux through cytochrome c oxidase: pH, ΔpH and fatty acids

1993 ◽  
Vol 21 (3) ◽  
pp. 781-784 ◽  
Author(s):  
John M. Wrigglesworth ◽  
Martyn A. Sharpe ◽  
Chris E. Cooper
Keyword(s):  
Fatty Acids ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Electron Flux

Role of mRNA stability and translation in the expression of cytochrome c oxidase during mouse myoblast differentiation: instability of the mRNA for the liver isoform of subunit VIa

2000 ◽  
Vol 351 (1) ◽  
pp. 133-142 ◽  
Author(s):  
Elizabeth L. THAMES ◽  
Danforth A. NEWTON ◽  
Samuel A. BLACK ◽  
Lewis H. BOWMAN
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Mrna Stability ◽  
Muscle Development ◽  
Actinomycin D ◽  
Myoblast Differentiation ◽  
Element Analysis ◽  
Rate Limiting ◽  
Mouse Myoblast

The role of mRNA stability and translation in mediating the expression of selected subunits of cytochrome c oxidase (COX) was examined during the differentiation of mouse myoblasts into myotubes in cell culture. The expression of the liver (L) and heart (H) isoforms of COX VIa, which undergo an isoform switch during muscle development, as well as of the Va subunit, which is expressed in all tissues, was analysed. The translational efficiencies of COX Va, VIa-L and VIa-H, as well as of mitochondrially encoded COX mRNAs, were inferred from their distribution in polysome gradients. These experiments suggest that the translational efficiencies of these mRNAs do not change during myoblast differentiation, although the nuclear mRNAs for COX Va, VIa-L and VIa-H are translated more efficiently than the mitochondrial mRNAs. Analysis of mRNA stability using the tetracycline-repressible promoter system and/or actinomycin D indicates that COX VIa-L mRNA decays with a half-life of ∼ 5–6h in both myoblasts and myotubes, whereas COX VIa-H and Va mRNAs decay with half-lives of > 15h in myotubes. This relative instability of COX VIa-L mRNA serves to limit the accumulation of COX VIa-L mRNA in these myogenic cells, as compared with mRNAs for other COX subunits. Deletion/replacement mapping experiments suggest that the COX VIa-L 3´ untranslated region contains a destabilization element. Analysis of the rate of poly(A) tail shortening on COX VIa-L and stable α-globin mRNAs suggests that the overall rate of poly(A) shortening per se is not rate limiting for the degradation of COX VIa-L mRNA.

Is the Internal Electron Transfer the Rate-Limiting Step in the Catalytic Cycle of Cytochrome c Oxidase?

1988 ◽  
Vol 550 (1 Cytochrome Ox) ◽  
pp. 161-166 ◽  
Author(s):  
PAOLO SARTI ◽  
GIOVANNI ANTONINI ◽  
RANCESCO MALATESTA ◽  
BEATRICE VALLONE ◽  
MAURIZIO BRUNORI
Keyword(s):  
Electron Transfer ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Catalytic Cycle ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Internal Electron ◽  
Rate Limiting

scholarly journals Cholate Disrupts Regulatory Functions of Cytochrome c Oxidase

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1579
Author(s):  
Rabia Ramzan ◽  
Jörg Napiwotzki ◽  
Petra Weber ◽  
Bernhard Kadenbach ◽  
Sebastian Vogt
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Mitochondrial Respiration ◽  
Sodium Cholate ◽  
Atp Inhibition ◽  
Ros Formation ◽  
Low Levels ◽  
Regulatory Functions ◽  
Relationship Of ◽  
Rate Limiting

Cytochrome c oxidase (CytOx), the oxygen-accepting and rate-limiting enzyme of mitochondrial respiration, binds with 10 molecules of ADP, 7 of which are exchanged by ATP at high ATP/ADP-ratios. These bound ATP and ADP can be exchanged by cholate, which is generally used for the purification of CytOx. Many crystal structures of isolated CytOx were performed with the enzyme isolated from mitochondria using sodium cholate as a detergent. Cholate, however, dimerizes the enzyme isolated in non-ionic detergents and induces a structural change as evident from a spectral change. Consequently, it turns off the “allosteric ATP-inhibition of CytOx”, which is reversibly switched on under relaxed conditions via cAMP-dependent phosphorylation and keeps the membrane potential and ROS formation in mitochondria at low levels. This cholate effect gives an insight into the structural-functional relationship of the enzyme with respect to ATP inhibition and its role in mitochondrial respiration and energy production.

scholarly journals Transient kinetics of subunit-III-depleted cytochrome c oxidase

1986 ◽  
Vol 234 (3) ◽  
pp. 569-572 ◽  
Author(s):  
F Malatesta ◽  
G Antonini ◽  
P Sarti ◽  
M Brunori
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Flash Photolysis ◽  
Order Rate Constant ◽  
Kinetic Properties ◽  
Transient Kinetics ◽  
Rate Limiting Step ◽  
Subunit Iii ◽  
The Stability ◽  
Rate Limiting

Cytochrome c oxidase from ox heart was depleted of subunit III and its transient kinetic properties studied by stopped-flow and flash photolysis. It was found that the overall mechanism of electron transfer is very similar for subunit-III-depleted and native oxidase, although significant differences in some kinetic parameters have been detected. These include the second-order rate constant for cytochrome c oxidation and the rate-limiting step of the overall process. Moreover, at low cytochrome c/oxidase ratios (where the number of reducing equivalents is insufficient), the rate of reoxidation of cytochrome a was found to be very slow, even in air, and in fact for the subunit-III-depleted enzyme is even slower than for the native oxidase. The stability of reduced cytochrome a excludes the likelihood that removal of subunit III leads to a new O2-binding site, and the result may be relevant to the lowered vectorial H+/e- stoichiometry. The subunit-III-depleted oxidase can be pulsed under appropriate conditions and its combination with CO is unchanged, as shown by kinetic experiments and difference spectroscopy.

scholarly journals Dual Functions of Mss51 Couple Synthesis of Cox1 to Assembly of Cytochrome c Oxidase in Saccharomyces cerevisiae Mitochondria

2009 ◽  
Vol 20 (20) ◽  
pp. 4371-4380 ◽  
Author(s):  
Xochitl Perez-Martinez ◽  
Christine A. Butler ◽  
Miguel Shingu-Vazquez ◽  
Thomas D. Fox
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Mrna Translation ◽  
Physical Interaction ◽  
Wild Type ◽  
Substantial Fraction ◽  
Saccharomyces Cerevisiae Mitochondria ◽  
Dynamic Assembly ◽  
Translational Activator ◽  
Rate Limiting

Functional interactions of the translational activator Mss51 with both the mitochondrially encoded COX1 mRNA 5′-untranslated region and with newly synthesized unassembled Cox1 protein suggest that it has a key role in coupling Cox1 synthesis with assembly of cytochrome c oxidase. Mss51 is present at levels that are near rate limiting for expression of a reporter gene inserted at COX1 in mitochondrial DNA, and a substantial fraction of Mss51 is associated with Cox1 protein in assembly intermediates. Thus, sequestration of Mss51 in assembly intermediates could limit Cox1 synthesis in wild type, and account for the reduced Cox1 synthesis caused by most yeast mutations that block assembly. Mss51 does not stably interact with newly synthesized Cox1 in a mutant lacking Cox14, suggesting that the failure of nuclear cox14 mutants to decrease Cox1 synthesis, despite their inability to assemble cytochrome c oxidase, is due to a failure to sequester Mss51. The physical interaction between Mss51 and Cox14 is dependent upon Cox1 synthesis, indicating dynamic assembly of early cytochrome c oxidase intermediates nucleated by Cox1. Regulation of COX1 mRNA translation by Mss51 seems to be an example of a homeostatic mechanism in which a positive effector of gene expression interacts with the product it regulates in a posttranslational assembly process.

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