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 Mitochondrial Membrane Dynamics—Functional Positioning of OPA1

Antioxidants ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 186 ◽  
Author(s):  
Hakjoo Lee ◽  
Yisang Yoon
Keyword(s):  
Mitochondrial Membrane ◽  
Proteolytic Cleavage ◽  
Membrane Dynamics ◽  
Mitochondrial Morphology ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Functional Differences ◽  
New Information ◽  
New Development

The maintenance of mitochondrial energetics requires the proper regulation of mitochondrial morphology, and vice versa. Mitochondrial dynamins control mitochondrial morphology by mediating fission and fusion. One of them, optic atrophy 1 (OPA1), is the mitochondrial inner membrane remodeling protein. OPA1 has a dual role in maintaining mitochondrial morphology and energetics through mediating inner membrane fusion and maintaining the cristae structure. OPA1 is expressed in multiple variant forms through alternative splicing and post-translational proteolytic cleavage, but the functional differences between these variants have not been completely understood. Recent studies generated new information regarding the role of OPA1 cleavage. In this review, we will first provide a brief overview of mitochondrial membrane dynamics by describing fission and fusion that are mediated by mitochondrial dynamins. The second part describes OPA1-mediated fusion and energetic maintenance, the role of OPA1 cleavage, and a new development in OPA1 function, in which we will provide new insight for what OPA1 does and what proteolytic cleavage of OPA1 is for.

scholarly journals The J-related Segment of Tim44 Is Essential for Cell Viability: A Mutant Tim44 Remains in the Mitochondrial Import Site, but Inefficiently Recruits mtHsp70 and Impairs Protein Translocation

1999 ◽  
Vol 145 (5) ◽  
pp. 961-972 ◽  
Author(s):  
Alessio Merlin ◽  
Wolfgang Voos ◽  
Ammy C. Maarse ◽  
Michiel Meijer ◽  
Nikolaus Pfanner ◽  
...  
Keyword(s):  
Protein Import ◽  
Protein Translocation ◽  
Adaptor Protein ◽  
Dependent Manner ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
J Proteins

Tim44 is a protein of the mitochondrial inner membrane and serves as an adaptor protein for mtHsp70 that drives the import of preproteins in an ATP-dependent manner. In this study we have modified the interaction of Tim44 with mtHsp70 and characterized the consequences for protein translocation. By deletion of an 18-residue segment of Tim44 with limited similarity to J-proteins, the binding of Tim44 to mtHsp70 was weakened. We found that in the yeast Saccharomyces cerevisiae the deletion of this segment is lethal. To investigate the role of the 18-residue segment, we expressed Tim44Δ18 in addition to the endogenous wild-type Tim44. Tim44Δ18 is correctly targeted to mitochondria and assembles in the inner membrane import site. The coexpression of Tim44Δ18 together with wild-type Tim44, however, does not stimulate protein import, but reduces its efficiency. In particular, the promotion of unfolding of preproteins during translocation is inhibited. mtHsp70 is still able to bind to Tim44Δ18 in an ATP-regulated manner, but the efficiency of interaction is reduced. These results suggest that the J-related segment of Tim44 is needed for productive interaction with mtHsp70. The efficient cooperation of mtHsp70 with Tim44 facilitates the translocation of loosely folded preproteins and plays a crucial role in the import of preproteins which contain a tightly folded domain.

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 The inner membrane protein Mdm33 controls mitochondrial morphology in yeast

2003 ◽  
Vol 160 (4) ◽  
pp. 553-564 ◽  
Author(s):  
Marlies Messerschmitt ◽  
Stefan Jakobs ◽  
Frank Vogel ◽  
Stefan Fritz ◽  
Kai Stefan Dimmer ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Hollow Spheres ◽  
Ultrastructural Level ◽  
Mitochondrial Morphology ◽  
Membrane Structures ◽  
Matrix Space ◽  
Gene Encoding ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Inner Membrane Protein

Mitochondrial distribution and morphology depend on MDM33, a Saccharomyces cerevisiae gene encoding a novel protein of the mitochondrial inner membrane. Cells lacking Mdm33 contain ring-shaped, mostly interconnected mitochondria, which are able to form large hollow spheres. On the ultrastructural level, these aberrant organelles display extremely elongated stretches of outer and inner membranes enclosing a very narrow matrix space. Dilated parts of Δmdm33 mitochondria contain well-developed cristae. Overexpression of Mdm33 leads to growth arrest, aggregation of mitochondria, and generation of aberrant inner membrane structures, including septa, inner membrane fragments, and loss of inner membrane cristae. The MDM33 gene is required for the formation of net-like mitochondria in mutants lacking components of the outer membrane fission machinery, and mitochondrial fusion is required for the formation of extended ring-like mitochondria in cells lacking the MDM33 gene. The Mdm33 protein assembles into an oligomeric complex in the inner membrane where it performs homotypic protein–protein interactions. Our results indicate that Mdm33 plays a distinct role in the mitochondrial inner membrane to control mitochondrial morphology. We propose that Mdm33 is involved in fission of the mitochondrial inner membrane.

scholarly journals The Assembly Pathway of the Mitochondrial Carrier Translocase Involves Four Preprotein Translocases

2008 ◽  
Vol 28 (13) ◽  
pp. 4251-4260 ◽  
Author(s):  
Karina Wagner ◽  
Natalia Gebert ◽  
Bernard Guiard ◽  
Katrin Brandner ◽  
Kaye N. Truscott ◽  
...  
Keyword(s):  
Protein Complexes ◽  
Intermembrane Space ◽  
Inner Membrane ◽  
Mitochondrial Carrier ◽  
Important Principle ◽  
Highly Active ◽  
Mitochondrial Inner Membrane ◽  
Assembly Pathway ◽  
Oligomeric Complex ◽  
The Individual

ABSTRACT The mitochondrial inner membrane contains preprotein translocases that mediate insertion of hydrophobic proteins. Little is known about how the individual components of these inner membrane preprotein translocases combine to form multisubunit complexes. We have analyzed the assembly pathway of the three membrane-integral subunits Tim18, Tim22, and Tim54 of the twin-pore carrier translocase. Tim54 displayed the most complex pathway involving four preprotein translocases. The precursor is translocated across the intermembrane space in a supercomplex of outer and inner membrane translocases. The TIM10 complex, which translocates the precursor of Tim22 through the intermembrane space, functions in a new posttranslocational manner: in case of Tim54, it is required for the integration of Tim54 into the carrier translocase. Tim18, the function of which has been unknown so far, stimulates integration of Tim54 into the carrier translocase. We show that the carrier translocase is built via a modular process and that each subunit follows a different assembly route. Membrane insertion and assembly into the oligomeric complex are uncoupled for each precursor protein. We propose that the mitochondrial assembly machinery has adapted to the needs of each membrane-integral subunit and that the uncoupling of translocation and oligomerization is an important principle to ensure continuous import and assembly of protein complexes in a highly active membrane.

scholarly journals Protein-dependent membrane remodeling in mitochondrial morphology and clathrin-mediated endocytosis

2021 ◽  
Author(s):  
Daryna Tarasenko ◽  
Michael Meinecke
Keyword(s):  
Plasma Membrane ◽  
Molecular Mechanisms ◽  
Membrane Receptors ◽  
Coated Vesicle ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Membrane Remodeling ◽  
Inner Membrane ◽  
Membrane Morphology ◽  
Mitochondrial Inner Membrane

AbstractCellular membranes can adopt a plethora of complex and beautiful shapes, most of which are believed to have evolved for a particular physiological reason. The closely entangled relationship between membrane morphology and cellular physiology is strikingly seen in membrane trafficking pathways. During clathrin-mediated endocytosis, for example, over the course of a minute, a patch of the more or less flat plasma membrane is remodeled into a highly curved clathrin-coated vesicle. Such vesicles are internalized by the cell to degrade or recycle plasma membrane receptors or to take up extracellular ligands. Other, steadier, membrane morphologies can be observed in organellar membranes like the endoplasmic reticulum or mitochondria. In the case of mitochondria, which are double membrane-bound, ubiquitous organelles of eukaryotic cells, especially the mitochondrial inner membrane displays an intricated ultrastructure. It is highly folded and consequently has a much larger surface than the mitochondrial outer membrane. It can adopt different shapes in response to cellular demands and changes of the inner membrane morphology often accompany severe diseases, including neurodegenerative- and metabolic diseases and cancer. In recent years, progress was made in the identification of molecules that are important for the aforementioned membrane remodeling events. In this review, we will sum up recent results and discuss the main players of membrane remodeling processes that lead to the mitochondrial inner membrane ultrastructure and in clathrin-mediated endocytosis. We will compare differences and similarities between the molecular mechanisms that peripheral and integral membrane proteins use to deform membranes.

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