scholarly journals Labeling of complex III, with [35S]diazobenzenesulfonate: orientation of this electron transfer segment in the mitochondrial inner membrane.

1979 ◽  
Vol 76 (2) ◽  
pp. 741-745 ◽  
Author(s):  
R. L. Bell ◽  
J. Sweetland ◽  
B. Ludwig ◽  
R. A. Capaldi
Keyword(s):  
Electron Transfer ◽  
Complex Iii ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane

The crystalline structure in the membranous preparations of mitochondrial complex III

1978 ◽  
Vol 36 (2) ◽  
pp. 292-293
Author(s):  
Junpei Asai
Keyword(s):  
Electron Transfer ◽  
Complex Iii ◽  
Molecular Architecture ◽  
Membrane Formation ◽  
Electron Transfer Chain ◽  
Ultrastructural Studies ◽  
Mitochondrial Inner Membrane ◽  
Beef Heart Mitochondria ◽  
The Individual ◽  
Transfer Chain

In 1962 Hatefi and his collegues showed biochemically the isolation of four complexes of the electron transfer chain from the mitochondria and the reconstitution of a complete electron transfer chain through re-association of the individual complexes. Tzagoloff et al demonstrated ultrastructurally the membrane formation by either single complex or a mixture of complexs. However, there have been a few direct ultrastructural studies in the molecular architecture of mitochondrial inner membrane. To understand the organization of Complex III (QH2-cytochrome c reductase) in the membrane, the membranes made from this complex under various conditions were examined ultrastructurally in the present study.Complex III was purified from beef heart mitochondria by the method of Heatefi et al as modified by Rieske et al. For the preparations of membrane formation, some samples of the purified complex suspended in the solution contained 0.66 M sucrose were diluted with 100 volumes of the mixture of 0.25 M in sucrose and 0.01 M in Tris-HCl (sucrose-Tris), pH 8.0 and were incubated for 30 min. at 0-4°C.

scholarly journals Dynamic subcompartmentalization of the mitochondrial inner membrane

2006 ◽  
Vol 175 (2) ◽  
pp. 237-247 ◽  
Author(s):  
Frank Vogel ◽  
Carsten Bornhövd ◽  
Walter Neupert ◽  
Andreas S. Reichert
Keyword(s):  
Protein Translocation ◽  
Physiological State ◽  
Protein Composition ◽  
Protein Translation ◽  
Complex Iii ◽  
Mitochondrial Morphology ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Metabolite Exchange ◽  
The Individual

The inner membrane of mitochondria is organized in two morphologically distinct domains, the inner boundary membrane (IBM) and the cristae membrane (CM), which are connected by narrow, tubular cristae junctions. The protein composition of these domains, their dynamics, and their biogenesis and maintenance are poorly understood at the molecular level. We have used quantitative immunoelectron microscopy to determine the distribution of a collection of representative proteins in yeast mitochondria belonging to seven major processes: oxidative phosphorylation, protein translocation, metabolite exchange, mitochondrial morphology, protein translation, iron–sulfur biogenesis, and protein degradation. We show that proteins are distributed in an uneven, yet not exclusive, manner between IBM and CM. The individual distributions reflect the physiological functions of proteins. Moreover, proteins can redistribute between the domains upon changes of the physiological state of the cell. Impairing assembly of complex III affects the distribution of partially assembled subunits. We propose a model for the generation of this dynamic subcompartmentalization of the mitochondrial inner membrane.

scholarly journals Relationship between the density distribution of intramembrane particles and electron transfer in the mitochondrial inner membrane as revealed by cholesterol incorporation.

1982 ◽  
Vol 94 (2) ◽  
pp. 387-393 ◽  
Author(s):  
H Schneider ◽  
M Höchli ◽  
C R Hackenbrock
Keyword(s):  
Electron Transfer ◽  
Surface Area ◽  
Lipid Bilayer ◽  
Average Distance ◽  
Membrane Lipid ◽  
Membrane Bilayer ◽  
Inner Membrane ◽  
Intramembrane Particles ◽  
Mitochondrial Inner Membrane ◽  
Membrane Lipid Bilayer

A low pH method of liposome-membrane fusion (Schneider et al., 1980, Proc. Natl. Acad. Sci. U. S. A. 77:442) was used to enrich the mitochondrial inner membrane lipid bilayer 30-700% with exogenous phospholipid and cholesterol. By varying the phospholipid-to-cholesterol ratio of the liposomes it was possible to incorporate specific amounts of cholesterol (up to 44 mol %) into the inner membrane bilayer in a controlled fashion. The membrane surface area increased proportionally to the increase in total membrane bilayer lipid. Inner membrane enriched with phospholipid only, or with phospholipid plus cholesterol up to 20 mol %, showed randomly distributed intramembrane particles (integral proteins) in the membrane plane, and the average distance between intramembrane particles increased proportionally to the amount of newly incorporated lipid. Membranes containing between 20 and 27 mol % cholesterol exhibited small clusters of intramembrane particles while cholesterol contents above 27 mol % resulted in larger aggregations of intramembrane particles. In phospholipid-enriched membranes with randomly dispersed intramembrane particles, electron transfer activities from NADH- and succinate-dehydrogenase to cytochrome c decreased proportionally to the increase in distance between the particles. In contrast, these electron-transfer activities increased with decreasing distances between intramembrane particles brought about by cholesterol incorporation. These results indicate that (a) catalytically interacting redox components in the mitochondrial inner membrane such as the dehydrogenase complexes, ubiquinone, and heme proteins are independent, laterally diffusible components; (b) the average distance between these redox components is effected by the available surface area of the membrane lipid bilayer; and (c) the distance over which redox components diffuse before collision and electron transfer mediates the rate of such transfer.

scholarly journals Mutations in the Membrane Anchor of Yeast Cytochrome c1 Compensate for the Absence of Oxa1p and Generate Carbonate-Extractable Forms of Cytochrome c1

Genetics ◽  
1998 ◽  
Vol 150 (2) ◽  
pp. 601-611
Author(s):  
Patrice Hamel ◽  
Claire Lemaire ◽  
Nathalie Bonnefoy ◽  
Paule Brivet-Chevillotte ◽  
Geneviève Dujardin
Keyword(s):  
Electron Transfer ◽  
Complex Iii ◽  
Membrane Anchor ◽  
Suppressor Activity ◽  
Complex Iv ◽  
Transfer Activity ◽  
Suppressor Function ◽  
Mitochondrial Inner Membrane ◽  
Cytochrome C1 ◽  
Inner Membrane Protein

Abstract Oxa1p is a mitochondrial inner membrane protein that is mainly required for the insertion/assembly of complex IV and ATP synthase and is functionally conserved in yeasts, humans, and plants. We have isolated several independent suppressors that compensate for the absence of Oxa1p. Molecular cloning and sequencing reveal that the suppressor mutations (CYT1-1 to -6) correspond to amino acid substitutions that are all located in the membrane anchor of cytochrome c1 and decrease the hydrophobicity of this anchor. Cytochrome c1 is a catalytic subunit of complex III, but the CYT1-1 mutation does not seem to affect the electron transfer activity. The double-mutant cyt1-1,164, which has a drastically reduced electron transfer activity, still retains the suppressor activity. Altogether, these results suggest that the suppressor function of cytochrome c1 is independent of its electron transfer activity. In addition to the membranebound cytochrome c1, carbonate-extractable forms accumulate in all the suppressor strains. We propose that these carbonate-extractable forms of cytochrome c1 are responsible for the suppressor function by preventing the degradation of the respiratory complex subunits that occur in the absence of Oxa1p.

scholarly journals NME6 is a phosphotransfer-inactive, monomeric NME/NDPK family member and functions in complexes at the interface of mitochondrial inner membrane and matrix

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bastien Proust ◽  
Martina Radić ◽  
Nikolina Škrobot Vidaček ◽  
Cécile Cottet ◽  
Stéphane Attia ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Nucleoside Diphosphate Kinase ◽  
Direct Interaction ◽  
Complex Iii ◽  
Mitochondrial Translation ◽  
Matrix Space ◽  
Inner Membrane ◽  
Network Characteristics ◽  
Mitochondrial Inner Membrane ◽  
Mitochondrial Ribosome

Abstract Background NME6 is a member of the nucleoside diphosphate kinase (NDPK/NME/Nm23) family which has key roles in nucleotide homeostasis, signal transduction, membrane remodeling and metastasis suppression. The well-studied NME1-NME4 proteins are hexameric and catalyze, via a phospho-histidine intermediate, the transfer of the terminal phosphate from (d)NTPs to (d)NDPs (NDP kinase) or proteins (protein histidine kinase). For the NME6, a gene/protein that emerged early in eukaryotic evolution, only scarce and partially inconsistent data are available. Here we aim to clarify and extend our knowledge on the human NME6. Results We show that NME6 is mostly expressed as a 186 amino acid protein, but that a second albeit much less abundant isoform exists. The recombinant NME6 remains monomeric, and does not assemble into homo-oligomers or hetero-oligomers with NME1-NME4. Consequently, NME6 is unable to catalyze phosphotransfer: it does not generate the phospho-histidine intermediate, and no NDPK activity can be detected. In cells, we could resolve and extend existing contradictory reports by localizing NME6 within mitochondria, largely associated with the mitochondrial inner membrane and matrix space. Overexpressing NME6 reduces ADP-stimulated mitochondrial respiration and complex III abundance, thus linking NME6 to dysfunctional oxidative phosphorylation. However, it did not alter mitochondrial membrane potential, mass, or network characteristics. Our screen for NME6 protein partners revealed its association with NME4 and OPA1, but a direct interaction was observed only with RCC1L, a protein involved in mitochondrial ribosome assembly and mitochondrial translation, and identified as essential for oxidative phosphorylation. Conclusions NME6, RCC1L and mitoribosomes localize together at the inner membrane/matrix space where NME6, in concert with RCC1L, may be involved in regulation of the mitochondrial translation of essential oxidative phosphorylation subunits. Our findings suggest new functions for NME6, independent of the classical phosphotransfer activity associated with NME proteins.

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