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Nature Communications Jul 2022Mitofusins reside on the outer mitochondrial membrane and regulate mitochondrial fusion, a physiological process that impacts diverse cellular processes. Mitofusins are...
Mitofusins reside on the outer mitochondrial membrane and regulate mitochondrial fusion, a physiological process that impacts diverse cellular processes. Mitofusins are activated by conformational changes and subsequently oligomerize to enable mitochondrial fusion. Here, we identify small molecules that directly increase or inhibit mitofusins activity by modulating mitofusin conformations and oligomerization. We use these small molecules to better understand the role of mitofusins activity in mitochondrial fusion, function, and signaling. We find that mitofusin activation increases, whereas mitofusin inhibition decreases mitochondrial fusion and functionality. Remarkably, mitofusin inhibition also induces minority mitochondrial outer membrane permeabilization followed by sub-lethal caspase-3/7 activation, which in turn induces DNA damage and upregulates DNA damage response genes. In this context, apoptotic death induced by a second mitochondria-derived activator of caspases (SMAC) mimetic is potentiated by mitofusin inhibition. These data provide mechanistic insights into the function and regulation of mitofusins as well as small molecules to pharmacologically target mitofusins.
Topics: GTP Phosphohydrolases; Mitochondria; Mitochondrial Dynamics; Mitochondrial Membranes; Mitochondrial Proteins; Signal Transduction
PubMed: 35798717
DOI: 10.1038/s41467-022-31324-1 -
The Enzymes 2023We present a brief review of the mitochondrial respiratory chain with emphasis on complexes I, III and IV, which contribute to the generation of protonmotive force...
We present a brief review of the mitochondrial respiratory chain with emphasis on complexes I, III and IV, which contribute to the generation of protonmotive force across the inner mitochondrial membrane, and drive the synthesis of ATP by the process called oxidative phosphorylation. The basic structural and functional details of these complexes are discussed. In addition, we briefly review the information on the so-called supercomplexes, aggregates of complexes I-IV, and summarize basic physiological aspects of cell respiration.
Topics: Mitochondrial Membranes; Electron Transport; Cell Respiration; Oxidative Phosphorylation
PubMed: 37945170
DOI: 10.1016/bs.enz.2023.05.001 -
Methods in Molecular Biology (Clifton,... 2021Complexome profiling combines blue native gel electrophoresis (BNE) and quantitative mass spectrometry to define an entire protein interactome of a cell, an organelle,...
Complexome profiling combines blue native gel electrophoresis (BNE) and quantitative mass spectrometry to define an entire protein interactome of a cell, an organelle, or a biological membrane preparation. The method allows the identification of protein assemblies with low abundance and detects dynamic processes of protein complex assembly. Applications of complexome profiling range from the determination of complex subunit compositions, assembly of single protein complexes, and supercomplexes to comprehensive differential studies between patients or disease models. This chapter describes the workflow of complexome profiling from sample preparation, mass spectrometry to data analysis with a bioinformatics tool.
Topics: Cell Line, Tumor; Chromatography, Liquid; Humans; Mass Spectrometry; Membrane Proteins; Mitochondria; Mitochondrial Membranes; Mitochondrial Proteins; Native Polyacrylamide Gel Electrophoresis; Peptides; Tandem Mass Spectrometry
PubMed: 33230779
DOI: 10.1007/978-1-0716-0834-0_19 -
Protein-dependent membrane remodeling in mitochondrial morphology and clathrin-mediated endocytosis.European Biophysics Journal : EBJ Mar 2021Cellular 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... (Review)
Review
Cellular 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.
Topics: Animals; Clathrin; Endocytosis; Humans; Membrane Proteins; Mitochondrial Membranes
PubMed: 33527201
DOI: 10.1007/s00249-021-01501-z -
Autophagy Mar 2023Mitophagy, as one of the most important cellular processes to ensure quality control of mitochondria, aims at transporting damaged, aging, dysfunctional or excess... (Review)
Review
Mitophagy, as one of the most important cellular processes to ensure quality control of mitochondria, aims at transporting damaged, aging, dysfunctional or excess mitochondria to vacuoles (plants and fungi) or lysosomes (mammals) for degradation and recycling. The normal functioning of mitophagy is critical for cellular homeostasis from yeasts to humans. Although the role of mitophagy has been well studied in mammalian cells and in certain model organisms, especially the budding yeast , our understanding of its significance in other fungi, particularly in pathogenic filamentous fungi, is still at the preliminary stage. Recent studies have shown that mitophagy plays a vital role in spore production, vegetative growth and virulence of pathogenic fungi, which are very different from its roles in mammal and yeast. In this review, we summarize the functions of mitophagy for mitochondrial quality and quantity control, fungal growth and pathogenesis that have been reported in the field of molecular biology over the past two decades. These findings may help researchers and readers to better understand the multiple functions of mitophagy and provide new perspectives for the study of mitophagy in fungal pathogenesis. AIM/LIR: Atg8-family interacting motif/LC3-interacting region; BAR: Bin-Amphiphysin-Rvs; BNIP3: BCL2 interacting protein 3; CK2: casein kinase 2; Cvt: cytoplasm-to-vacuole targeting; ER: endoplasmic reticulum; IMM: inner mitochondrial membrane; mETC: mitochondrial electron transport chain; OMM: outer mitochondrial membrane; OPTN: optineurin; PAS: phagophore assembly site; PD: Parkinson disease; PE: phosphatidylethanolamine; PHB2: prohibitin 2; PX: Phox homology; ROS, reactive oxygen species; TM: transmembrane.
Topics: Humans; Animals; Mitophagy; Autophagy; Mitochondria; Mitochondrial Membranes; Saccharomyces cerevisiae; Mammals
PubMed: 35793406
DOI: 10.1080/15548627.2022.2098452 -
FEBS Letters Apr 2021Mitochondria play a key role in cellular signalling, metabolism and energetics. Proper architecture and remodelling of the inner mitochondrial membrane are essential for... (Review)
Review
Mitochondria play a key role in cellular signalling, metabolism and energetics. Proper architecture and remodelling of the inner mitochondrial membrane are essential for efficient respiration, apoptosis and quality control in the cell. Several protein complexes including mitochondrial contact site and cristae organizing system (MICOS), F F -ATP synthase, and Optic Atrophy 1 (OPA1), facilitate formation, maintenance and stability of cristae membranes. MICOS, the F F -ATP synthase, OPA1 and inner membrane phospholipids such as cardiolipin and phosphatidylethanolamine interact with each other to organize the inner membrane ultra-structure and remodel cristae in response to the cell's demands. Functional alterations in these proteins or in the biosynthesis pathway of cardiolipin and phosphatidylethanolamine result in an aberrant inner membrane architecture and impair mitochondrial function. Mitochondrial dysfunction and abnormalities hallmark several human conditions and diseases including neurodegeneration, cardiomyopathies and diabetes mellitus. Yet, they have long been regarded as secondary pathological effects. This review discusses emerging evidence of a direct relationship between protein- and lipid-dependent regulation of the inner mitochondrial membrane morphology and diseases such as fatal encephalopathy, Leigh syndrome, Parkinson's disease, and cancer.
Topics: Apoptosis; Humans; Mitochondria; Mitochondrial Diseases; Mitochondrial Membranes; Mitochondrial Proteins
PubMed: 33837538
DOI: 10.1002/1873-3468.14089 -
Methods in Molecular Biology (Clifton,... 2022Analyzing the membrane integrity and topology of a mitochondrial protein is essential for truly understanding its function. In this chapter, we demonstrate how to...
Analyzing the membrane integrity and topology of a mitochondrial protein is essential for truly understanding its function. In this chapter, we demonstrate how to analyze mitochondrial membrane proteins using both an immunological-based assay and an in vivo self-assembling GFP approach. First, immunological approaches to investigate the solubility or membrane association of a protein within mitochondria are described. With this method, we demonstrate how the topology of soluble domains of a membrane-integrated protein can be determined. Using protein-specific antibodies, the localization of the soluble domains of a protein are analyzed by a proteolytic-cleavage approach using proteinase K in mitochondria, outer membrane-ruptured mitochondria, and solubilized mitochondrial membranes. In a second approach, we determine the topology of plant mitochondrial proteins using an in vivo self-assembling GFP localization approach.
Topics: Antibodies; Endopeptidase K; Intracellular Membranes; Membrane Proteins; Mitochondria; Mitochondrial Membranes; Mitochondrial Proteins
PubMed: 34545493
DOI: 10.1007/978-1-0716-1653-6_13 -
EMBO Reports Nov 2023The mitochondrial respiratory chain (MRC) is a key energy transducer in eukaryotic cells. Four respiratory chain complexes cooperate in the transfer of electrons derived... (Review)
Review
The mitochondrial respiratory chain (MRC) is a key energy transducer in eukaryotic cells. Four respiratory chain complexes cooperate in the transfer of electrons derived from various metabolic pathways to molecular oxygen, thereby establishing an electrochemical gradient over the inner mitochondrial membrane that powers ATP synthesis. This electron transport relies on mobile electron carries that functionally connect the complexes. While the individual complexes can operate independently, they are in situ organized into large assemblies termed respiratory supercomplexes. Recent structural and functional studies have provided some answers to the question of whether the supercomplex organization confers an advantage for cellular energy conversion. However, the jury is still out, regarding the universality of these claims. In this review, we discuss the current knowledge on the functional significance of MRC supercomplexes, highlight experimental limitations, and suggest potential new strategies to overcome these obstacles.
Topics: Mitochondrial Membranes; Electron Transport; Mitochondria
PubMed: 37828827
DOI: 10.15252/embr.202357092 -
Journal of Internal Medicine Jun 2020Mitochondria play central roles in cellular energetics, metabolism and signalling. Efficient respiration, mitochondrial quality control, apoptosis and inheritance of... (Review)
Review
Mitochondria play central roles in cellular energetics, metabolism and signalling. Efficient respiration, mitochondrial quality control, apoptosis and inheritance of mitochondrial DNA depend on the proper architecture of the mitochondrial membranes and a dynamic remodelling of inner membrane cristae. Defects in mitochondrial architecture can result in severe human diseases affecting predominantly the nervous system and the heart. Inner membrane morphology is generated and maintained in particular by the mitochondrial contact site and cristae organizing system (MICOS), the F F -ATP synthase, the fusion protein OPA1/Mgm1 and the nonbilayer-forming phospholipids cardiolipin and phosphatidylethanolamine. These protein complexes and phospholipids are embedded in a network of functional interactions. They communicate with each other and additional factors, enabling them to balance different aspects of cristae biogenesis and to dynamically remodel the inner mitochondrial membrane. Genetic alterations disturbing these membrane-shaping factors can lead to human pathologies including fatal encephalopathy, dominant optic atrophy, Leigh syndrome, Parkinson's disease and Barth syndrome.
Topics: DNA, Mitochondrial; Humans; Mitochondria; Mitochondrial Diseases; Mitochondrial Membranes; Mitochondrial Proteins; Mitochondrial Proton-Translocating ATPases; Mutation
PubMed: 32012363
DOI: 10.1111/joim.13031 -
International Journal of Molecular... May 2022Mitochondria import about 1000 precursor proteins from the cytosol. The translocase of the outer membrane (TOM complex) forms the major entry site for precursor... (Review)
Review
Mitochondria import about 1000 precursor proteins from the cytosol. The translocase of the outer membrane (TOM complex) forms the major entry site for precursor proteins. Subsequently, membrane-bound protein translocases sort the precursor proteins into the outer and inner membrane, the intermembrane space, and the matrix. The phospholipid composition of mitochondrial membranes is critical for protein import. Structural and biochemical data revealed that phospholipids affect the stability and activity of mitochondrial protein translocases. Integration of proteins into the target membrane involves rearrangement of phospholipids and distortion of the lipid bilayer. Phospholipids are present in the interface between subunits of protein translocases and affect the dynamic coupling of partner proteins. Phospholipids are required for full activity of the respiratory chain to generate membrane potential, which in turn drives protein import across and into the inner membrane. Finally, outer membrane protein translocases are closely linked to organellar contact sites that mediate lipid trafficking. Altogether, intensive crosstalk between mitochondrial protein import and lipid biogenesis controls mitochondrial biogenesis.
Topics: Carrier Proteins; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Membranes; Mitochondrial Proteins; Phospholipids; Protein Transport; Saccharomyces cerevisiae Proteins
PubMed: 35563660
DOI: 10.3390/ijms23095274