Heme <i>a</i> induces assembly of rat liver cytochrome c oxidase subunits I‐III in isolated mitochondria

Wielburski, Antek; Nelson, Bruce R.

doi:10.1016/0014-5793(84)81302-2

Cited by 31 publications

(15 citation statements)

References 20 publications

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“…tOxygen reduction activity is measured polarographically in a reaction containing 50 mM KH2PO4 at pH 6.5, 1 mM lauryl maltoside, 2.8 mM ascorbate, 0.55 mM N,N,N',N'-tetramethyl-p-phenylenediamine, 30 tLM horse-heart cytochrome c, and…”

Section: Resultsmentioning

confidence: 99%

Definition of the catalytic site of cytochrome c oxidase: specific ligands of heme a and the heme a3-CuB center.

Shapleigh

Hosler

Tecklenburg

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

110

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The three-subunit aa3-type cytochrome c oxidase (EC 1.9.3.1) of Rhodobacter sphaeroides is structurally and functionally homologous to the more complex mitochondrial oxidase. The largest subunit, subunit I, is highly conserved and predicted to contain 12 transmembrane segments that provide all the ligands for three of the four metal centers: heme a, heme a3, and CUB. A variety of spectroscopic techniques identify these ligands as histidines. We have used site-directed mutagenesis to change all the conserved histidines within subunit I of cytochrome c oxidase from Rb. sphaeroides. Analysis of the membrane-bound and purified mutant proteins by optical absorption and resonance Raman spectroscopy indicates that His-102 and His-421 are the ligands of heme a, while His-284, His-333, His-334, and His-419 ligate the heme ar-CuB center. To satisfy this ligation assignment, helices II, VI, VII, and X, which contain these histidine residues, must be in close proximity. These data provide empirical evidence regarding the three-dimensional protein structure at the catalytic core of cytochrome c oxidase.Cytochrome c oxidase (EC 1.9.3.1) catalyzes the reduction of oxygen to water at the terminus of the mitochondrial respiratory chain, the principal energy-generating system of eukaryotic organisms (for recent reviews see refs. 1 and 2). Energy conservation is achieved by the coupling of electron transfer through the heme and copper metal centers to proton translocation across the membrane (3). To understand this coupling process it is essential to have a detailed description of the protein structures that form the heme-and copperbinding sites.A number of bacteria synthesize cytochrome c oxidases that are simpler in structure but functionally homologous to the mitochondrial enzymes (2, 4, 5). The aa3-type cytochrome c oxidase from Rhodobacter sphaeroides has recently been purified as a complex of three subunits that are homologues ofthe three mitochondrially encoded subunits of the eukaryotic oxidase (J.P.H. and S.F.-M., unpublished results). The Rb. sphaeroides oxidase has remarkably high turnover (Vm > 1800 sec-1), pumps protons efficiently (0.7 H+/e-) in reconstituted proteoliposomes, and is spectroscopically similar to beef heart cytochrome c oxidase. This preparation clearly establishes the oxidase from Rb. sphaeroides as an excellent bacterial model for examining the structural basis of the catalytic function of the more complex eukaryotic enzyme. The utility of Rb. sphaeroides as a genetic system for analyzing structure/function relationships has been established in previous studies ofthe photosynthetic reaction center (6) and the cytochrome bc complex (7).The genes coding for the three subunits of the Rb. sphaeroides aa3-type oxidase have been cloned and sequenced (refs. 8 and 9 and unpublished data). The genetic organization and deduced amino acid sequences are very similar to those from the closely related bacterium Paracoccus denitrificans (2, 10-12). In addition, subunit I shows 50% sequence identity to subun...

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Section: Resultsmentioning

confidence: 99%

Definition of the catalytic site of cytochrome c oxidase: specific ligands of heme a and the heme a3-CuB center.

Shapleigh

Hosler

Tecklenburg

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

110

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“…The amount of heme-a present in the cell determines the rate of complex IV assembly [102,108,116]. Three main conditions inhibit the production of heme-a: hypoxia, low heme production and pantothenate deficiency [117,118].…”

Section: Dysregulation Of Heme Levels Can Cause Serious Diseasesmentioning

confidence: 99%

Heme: a versatile signaling molecule controlling the activities of diverse regulators ranging from transcription factors to MAP kinases

2006

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“…Mitochondrial complex IV, the only enzyme in cells that contains heme-a (see below) (4), declines in AD (5)(6)(7)(8). Heme-a is rate limiting for the assembly of complex IV (9). Furthermore, an inhibitor of muscarinic acetylcholine receptor binding, which increased in AD brain, was suggested to be heme (10,11).…”

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confidence: 99%

A role for heme in Alzheimer's disease: Heme binds amyloid β and has altered metabolism

Atamna

Frey

2004

Proc. Natl. Acad. Sci. U.S.A.

235

239

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Heme is a common factor linking several metabolic perturbations in Alzheimer's disease (AD), including iron metabolism, mitochondrial complex IV, heme oxygenase, and bilirubin. Therefore, we determined whether heme metabolism was altered in temporal lobes obtained at autopsy from AD patients and age-matched nondemented subjects. AD brain demonstrated 2.5-fold more heme-b (P < 0.01) and 26% less heme-a (P ‫؍‬ 0.16) compared with controls, resulting in a highly significant 2.9-fold decrease in heme-a͞heme-b ratio (P < 0.001). Moreover, the strong Pearson correlation between heme-a and heme-b measured in control individuals (r 2 ‫؍‬ 0.66, P < 0.002, n ‫؍‬ 11) was abolished in AD subjects (r 2 ‫؍‬ 0.076, P ‫؍‬ 0.39, n ‫؍‬ 12). The level of ferrochelatase (which makes heme-b in the mitochondrial matrix) in AD subjects was 4.2 times (P < 0.04) that in nondemented controls, suggesting up-regulated heme synthesis. To look for a possible connection between these observations and established mechanisms in AD pathology, we examined possible interactions between amyloid ␤ (A␤) and heme. A␤(1-40) and A␤(1-42) induced a redshift of 15-20 nm in the spectrum of heme-b and heme-a, suggesting that heme binds A␤, likely to one or more of the histidine residues. Lastly, in a tissue culture model, we found that clioquinol, a metal chelator in clinical trials for AD therapy, decreased intracellular heme. In light of these observations, we have proposed a model of AD pathobiology in which intracellular A␤ complexes with free heme, thereby decreasing its bioavailability (e.g., heme-a) and resulting in functional heme deficiency. The model integrates disparate observations, including A␤, mitochondrial dysfunction, cholesterol, and the proposed efficacy of clioquinol.mitochondria ͉ heme-a ͉ iron ͉ clioquinol ͉ ferrochelatase H eme (ferriprotoporphyrin IX) metabolism appears altered in the brains of Alzheimer's disease (AD) patients. Heme oxygenase (HO) increases in AD (1, 2), and the level of bilirubin (one of the products of heme degradation by HO) is increased in AD patients (3). Mitochondrial complex IV, the only enzyme in cells that contains heme-a (see below) (4), declines in AD (5-8). Heme-a is rate limiting for the assembly of complex IV (9). Furthermore, an inhibitor of muscarinic acetylcholine receptor binding, which increased in AD brain, was suggested to be heme (10, 11). Therefore, we studied heme metabolism in AD brain and nondemented age-matched normal subjects.Heme-b, the product of ferrochelatase (FC) (also known as protoheme), is produced in the mitochondrial matrix (12, 13) and is the precursor for heme-c and heme-a. The structure of heme-c is similar to that of heme-b, but it is covalently attached to a few specific proteins (reviewed in ref. 14). Heme-b and heme-a exist in two major pools in the cell, free and protein-associated. Conversion of heme-b to heme-a requires farnasylation and oxidation (15). Farnesyl-pyrophsphate (FPP) is the precursor for the farnesyl moiety in heme-a, cholesterol, dolichol, farnesylation ...

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Heme a induces assembly of rat liver cytochrome c oxidase subunits I‐III in isolated mitochondria

Cited by 31 publications

References 20 publications

Definition of the catalytic site of cytochrome c oxidase: specific ligands of heme a and the heme a3-CuB center.

Definition of the catalytic site of cytochrome c oxidase: specific ligands of heme a and the heme a3-CuB center.

Heme: a versatile signaling molecule controlling the activities of diverse regulators ranging from transcription factors to MAP kinases

A role for heme in Alzheimer's disease: Heme binds amyloid β and has altered metabolism

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