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Arrangement of electron transport chain components in bovine mitochondrial supercomplex I1III2IV1.

ABSTRACT: The respiratory chain in the inner mitochondrial membrane contains three large multi-enzyme complexes that together establish the proton gradient for ATP synthesis, and assemble into a supercomplex. A 19-Å 3D map of the 1.7-MDa amphipol-solubilized supercomplex I(1)III(2)IV(1) from bovine heart obtained by single-particle electron cryo-microscopy reveals an amphipol belt replacing the membrane lipid bilayer. A precise fit of the X-ray structures of complex I, the complex III dimer, and monomeric complex IV indicates distances of 13 nm between the ubiquinol-binding sites of complexes I and III, and of 10-11 nm between the cytochrome c binding sites of complexes III and IV. The arrangement of respiratory chain complexes suggests two possible pathways for efficient electron transfer through the supercomplex, of which the shorter branch through the complex III monomer proximal to complex I may be preferred.

SUBMITTER: Althoff T

PROVIDER: S-EPMC3243592 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature

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Arrangement of electron transport chain components in bovine mitochondrial supercomplex I1III2IV1.

Althoff Thorsten T Mills Deryck J DJ Popot Jean-Luc JL Kühlbrandt Werner W

The EMBO journal 20110909 22

The respiratory chain in the inner mitochondrial membrane contains three large multi-enzyme complexes that together establish the proton gradient for ATP synthesis, and assemble into a supercomplex. A 19-Å 3D map of the 1.7-MDa amphipol-solubilized supercomplex I(1)III(2)IV(1) from bovine heart obtained by single-particle electron cryo-microscopy reveals an amphipol belt replacing the membrane lipid bilayer. A precise fit of the X-ray structures of complex I, the complex III dimer, and monomeric ...[more]

PMID: 21909073

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Project description:Pulmonary hypertension is associated with pronounced exercise intolerance (decreased V???O2 max) that can significantly impact quality of life. The cause of exercise intolerance in pulmonary hypertension remains unclear. Mitochondrial supercomplexes are large respiratory assemblies of individual electron transport chain complexes which can promote more efficient respiration. In this study, we examined pulmonary hypertension and exercise-induced changes in skeletal muscle electron transport chain protein expression and supercomplex assembly. Pulmonary arterial hypertension was induced in rats with the Sugen/Hypoxia model (10% FiO2, three weeks). Pulmonary arterial hypertension and control rats were assigned to an exercise training protocol group or kept sedentary for one month. Cardiac function and V???O2 max were assessed at the beginning and end of exercise training. Red (Type 1-oxidative muscle) and white (Type 2-glycolytic muscle) gastrocnemius were assessed for changes in electron transport chain complex protein expression and supercomplex assembly via SDS- and Blue Native-PAGE. Results showed that pulmonary arterial hypertension caused a significant decrease in V???O2 max via treadmill testing that was improved with exercise (P?<?0.01). Decreases in cardiac output and pulmonary acceleration time due to pulmonary arterial hypertension were not improved with exercise. Pulmonary arterial hypertension reduced expression in individual electron transport chain complex protein expression (NDUFB8 (CI), SDHB (CII), Cox IV (CIV), but not UQCRC2 (CIII), or ATP5a (CV)) in red gastrocnemius muscle. Both red gastrocnemius and white gastrocnemius electron transport chain expression was unaffected by exercise. However, non-denaturing Blue Native-PAGE analysis of mitochondrial supercomplexes demonstrated increases with exercise training in pulmonary arterial hypertension in the red gastrocnemius but not white gastrocnemius muscle. Pulmonary arterial hypertension-induced exercise intolerance is improved with exercise and is associated with muscle type specific alteration in mitochondrial supercomplex assembly and expression of mitochondrial electron transport chain proteins.

Dataset Information

Arrangement of electron transport chain components in bovine mitochondrial supercomplex I1III2IV1.

Publications

Arrangement of electron transport chain components in bovine mitochondrial supercomplex I1III2IV1.

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