scholarly journals Ovarian carcinoma immunoreactive antigen-like protein 2 (OCIAD2) is a novel metazoan specific complex III assembly factor

2020 ◽  
Author(s):  
Katarzyna Justyna Chojnacka ◽  
Karthik Mohanraj ◽  
Sylvie Callegari ◽  
Ben Hur Marins Mussulini ◽  
Praveenraj Elanchelyan ◽  
...  
Keyword(s):  
Ovarian Carcinoma ◽  
Gene Editing ◽  
Complex Iii ◽  
Hek293 Cells ◽  
Mitochondrial Morphology ◽  
Mitochondrial Inner Membrane ◽  
Transport Chain ◽  
Specific Complex ◽  
Assembly Factor ◽  
Insight Into

ABSTRACTAssembly of the dimeric complex III (CIII2) in the mitochondrial inner membrane is an intricate process in which many factors are involved. Despite many studies this process is yet to be completely understood. Here we report the identification of human OCIAD2 (Ovarian Carcinoma Immunoreactive Antigen domain containing protein 2) protein as an assembly factor for CIII2. OCIAD2 was found deregulated in several carcinomas and in some neurodegenerative disorders; however its non-pathological role was not elucidated to date. We have shown that OCIAD2 localizes to mitochondria and interacts with electron transport chain (ETC) proteins. Complete loss of OCIAD2 using gene editing in HEK293 cells resulted in abnormal mitochondrial morphology, decrease assembly of both CIII2 and supercomplex III2+IV and decreased activities of complex I and III. Identification of OCIAD2 as a protein required for assembly of functional CIII2 provides a new insight into the biogenesis and architecture of the ETC. Elucidating the mechanism of OCIAD2 action is important both for the understanding of cellular metabolism and for understanding of its role in the malignant transformation.

scholarly journals C11orf83, a Mitochondrial Cardiolipin-Binding Protein Involved inbc1Complex Assembly and Supercomplex Stabilization

2015 ◽  
Vol 35 (7) ◽  
pp. 1139-1156 ◽  
Author(s):  
Marjorie Desmurs ◽  
Michelangelo Foti ◽  
Etienne Raemy ◽  
Frédéric Maxime Vaz ◽  
Jean-Claude Martinou ◽  
...  
Keyword(s):  
Intermembrane Space ◽  
Core Complex ◽  
Mitochondrial Inner Membrane ◽  
Transport Chain ◽  
Mammalian Mitochondria ◽  
Assembly Factor ◽  
Subsequent Elimination ◽  
Inner Membrane Protein ◽  
Selection Of ◽  
Higher Sensitivity

Mammalian mitochondria may contain up to 1,500 different proteins, and many of them have neither been confidently identified nor characterized. In this study, we demonstrated that C11orf83, which was lacking experimental characterization, is a mitochondrial inner membrane protein facing the intermembrane space. This protein is specifically associated with thebc1complex of the electron transport chain and involved in the early stages of its assembly by stabilizing thebc1core complex. C11orf83 displays some overlapping functions with Cbp4p, a yeastbc1complex assembly factor. Therefore, we suggest that C11orf83, now called UQCC3, is the functional human equivalent of Cbp4p. In addition, C11orf83 depletion in HeLa cells caused abnormal crista morphology, higher sensitivity to apoptosis, a decreased ATP level due to impaired respiration and subtle, but significant, changes in cardiolipin composition. We showed that C11orf83 binds to cardiolipin by its α-helices 2 and 3 and is involved in the stabilization ofbc1complex-containing supercomplexes, especially the III2/IV supercomplex. We also demonstrated that the OMA1 metalloprotease cleaves C11orf83 in response to mitochondrial depolarization, suggesting a role in the selection of cells with damaged mitochondria for their subsequent elimination by apoptosis, as previously described for OPA1.

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 MINOS1 is a conserved component of mitofilin complexes and required for mitochondrial function and cristae organization

2012 ◽  
Vol 23 (2) ◽  
pp. 247-257 ◽  
Author(s):  
Alwaleed K. Alkhaja ◽  
Daniel C. Jans ◽  
Miroslav Nikolov ◽  
Milena Vukotic ◽  
Oleksandr Lytovchenko ◽  
...  
Keyword(s):  
Carbon Sources ◽  
Ultrastructural Level ◽  
Yeast Cells ◽  
Mitochondrial Morphology ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Inner Membrane Protein ◽  
Protein Rich ◽  
Boundary Membrane ◽  
Insight Into

The inner membrane of mitochondria is especially protein rich and displays a unique morphology characterized by large invaginations, the mitochondrial cristae, and the inner boundary membrane, which is in proximity to the outer membrane. Mitochondrial inner membrane proteins appear to be not evenly distributed in the inner membrane, but instead organize into functionally distinct subcompartments. It is unknown how the organization of the inner membrane is achieved. We identified MINOS1/MIO10 (C1orf151/YCL057C-A), a conserved mitochondrial inner membrane protein. mio10-mutant yeast cells are affected in growth on nonfermentable carbon sources and exhibit altered mitochondrial morphology. At the ultrastructural level, mutant mitochondria display loss of inner membrane organization. Proteomic analyses reveal MINOS1/Mio10 as a novel constituent of Mitofilin/Fcj1 complexes in human and yeast mitochondria. Thus our analyses reveal new insight into the composition of the mitochondrial inner membrane organizing machinery.

scholarly journals TIMMDC1/C3orf1 Functions as a Membrane-Embedded Mitochondrial Complex I Assembly Factor through Association with the MCIA Complex

2013 ◽  
Vol 34 (5) ◽  
pp. 847-861 ◽  
Author(s):  
Virginia Guarani ◽  
Joao Paulo ◽  
Bo Zhai ◽  
Edward L. Huttlin ◽  
Steven P. Gygi ◽  
...  
Keyword(s):  
Complex I ◽  
Cellular Respiration ◽  
Inner Membrane ◽  
Atp Production ◽  
Mitochondrial Inner Membrane ◽  
Transport Chain ◽  
Assembly Factors ◽  
Assembly Factor ◽  
Interaction Proteomics ◽  
Complex I Assembly

Complex I (CI) of the electron transport chain, a large membrane-embedded NADH dehydrogenase, couples electron transfer to the release of protons into the mitochondrial inner membrane space to promote ATP production through ATP synthase. In addition to being a central conduit for ATP production, CI activity has been linked to neurodegenerative disorders, including Parkinson's disease. CI is built in a stepwise fashion through the actions of several assembly factors. We employed interaction proteomics to interrogate the molecular associations of 15 core subunits and assembly factors previously linked to human CI deficiency, resulting in a network of 101 proteins and 335 interactions (edges). TIMMDC1, a predicted 4-pass membrane protein, reciprocally associated with multiple members of the MCIA CI assembly factor complex and core CI subunits and was localized in the mitochondrial inner membrane, and its depletion resulted in reduced CI activity and cellular respiration. Quantitative proteomics demonstrated a role for TIMMDC1 in assembly of membrane-embedded and soluble arms of the complex. This study defines a new membrane-embedded CI assembly factor and provides a resource for further analysis of CI biology.

scholarly journals AB0031 T HELPER 17 CELLS WERE SIGNIFICANTLY DECREASED BY MITOCHONDRIAL ELECTRON TRANSPORT CHAIN COMPLEX INHIBITOR IN PATIENTS WITH RHEUMATOID ARTHRITIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1318.2-1318
Author(s):  
H. R. Lee ◽  
S. J. Yoo ◽  
J. Kim ◽  
I. S. Yoo ◽  
C. K. Park ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Electron Transport ◽  
Disease Activity ◽  
Th17 Cells ◽  
Electron Transport Chain ◽  
Chain Complex ◽  
Complex Iii ◽  
Mitochondrial Electron Transport Chain ◽  
Transport Chain ◽  
Healthy Control

Background:Reactive oxygen species (ROS) and T helper 17 (TH17) cells have been known to play an important role in the pathogenesis of rheumatoid arthritis (RA). However, the interrelationship between ROS and TH17 remains unclear in RAObjectives:To explore whether ROS affect TH17 cells in peripheral blood mononuclear cells (PBMC) of RA patients, we analyzed ROS expressions among T cell subsets following treatment with mitochondrial electron transport chain complex inhibitors.Methods:Blood samples were collected from 40 RA patients and 10 healthy adult volunteers. RA activity was divided according to clinical parameter DAS28. PBMC cells were obtained from the whole blood using lymphocyte separation medium density gradient centrifugation. Following PBMC was stained with Live/Dead stain dye, cells were incubated with antibodies for CD3, CD4, CD8, and CD25. After fixation and permeabilization, samples were stained with antibodies for FoxP3 and IL-17A. MitoSox were used for mitochondrial specific staining.Results:The frequency of TH17 cells was increased by 4.83 folds in moderate disease activity group (5.1>DAS28≥3.2) of RA patients compared to healthy control. Moderate RA activity patients also showed higher ratio of TH17/Treg than healthy control (3.57 folds). All RA patients had elevated expression of mitochondrial specific ROS than healthy control. When PBMC cells were treated with 2.5uM of antimycin A (mitochondrial electron transport chain complex III inhibitor) for 16 h, the frequency of TH17 cells was significantly decreased.Conclusion:The mitochondrial electron transport chain complex III inhibitor markedly downregulated the frequency of TH17 cells in moderate disease activity patients with RA. These findings provide a novel approach to regulate TH17 function in RA through mitochondrial metabolism related ROS production.References:[1]Szekanecz, Z., et al., New insights in synovial angiogenesis. Joint Bone Spine, 2010. 77(1): p. 13-9.[2]Prevoo, M.L., et al., Modified disease activity scores that include twenty-eight-joint counts. Development and validation in a prospective longitudinal study of patients with rheumatoid arthritis. Arthritis Rheum, 1995. 38(1): p. 44-8.Disclosure of Interests:None declared

scholarly journals Complex II subunit SDHD is critical for cell growth and metabolism, which can be partially restored with a synthetic ubiquinone analog

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Aloka B. Bandara ◽  
Joshua C. Drake ◽  
David A. Brown
Keyword(s):  
Mammalian Cells ◽  
Krebs Cycle ◽  
Atp Synthesis ◽  
Hek293 Cells ◽  
Knockout Mutant ◽  
Complex Ii ◽  
Growth Defects ◽  
Transport Chain ◽  
Mutant Cells

Abstract Background Succinate dehydrogenase (Complex II) plays a dual role in respiration by catalyzing the oxidation of succinate to fumarate in the mitochondrial Krebs cycle and transferring electrons from succinate to ubiquinone in the mitochondrial electron transport chain (ETC). Mutations in Complex II are associated with a number of pathologies. SDHD, one of the four subunits of Complex II, serves by anchoring the complex to the inner-membrane and transferring electrons from the complex to ubiquinone. Thus, modeling SDHD dysfunction could be a valuable tool for understanding its importance in metabolism and developing novel therapeutics, however no suitable models exist. Results Via CRISPR/Cas9, we mutated SDHD in HEK293 cells and investigated the in vitro role of SDHD in metabolism. Compared to the parent HEK293, the knockout mutant HEK293ΔSDHD produced significantly less number of cells in culture. The mutant cells predictably had suppressed Complex II-mediated mitochondrial respiration, but also Complex I-mediated respiration. SDHD mutation also adversely affected glycolytic capacity and ATP synthesis. Mutant cells were more apoptotic and susceptible to necrosis. Treatment with the mitochondrial therapeutic idebenone partially improved oxygen consumption and growth of mutant cells. Conclusions Overall, our results suggest that SDHD is vital for growth and metabolism of mammalian cells, and that respiratory and growth defects can be partially restored with treatment of a ubiquinone analog. This is the first report to use CRISPR/Cas9 approach to construct a knockout SDHD cell line and evaluate the efficacy of an established mitochondrial therapeutic candidate to improve bioenergetic capacity.

scholarly journals Assembly factors monitor sequential hemylation of cytochrome b to regulate mitochondrial translation

2014 ◽  
Vol 205 (4) ◽  
pp. 511-524 ◽  
Author(s):  
Markus Hildenbeutel ◽  
Eric L. Hegg ◽  
Katharina Stephan ◽  
Steffi Gruschke ◽  
Brigitte Meunier ◽  
...  
Keyword(s):  
Electron Transport ◽  
Cytochrome B ◽  
Mitochondrial Respiratory Chain ◽  
Complex Iii ◽  
Mitochondrial Translation ◽  
Respiratory Chain Complexes ◽  
Mitochondrial Inner Membrane ◽  
Sequence Of Events ◽  
Chain Complexes ◽  
Assembly Factors

Mitochondrial respiratory chain complexes convert chemical energy into a membrane potential by connecting electron transport with charge separation. Electron transport relies on redox cofactors that occupy strategic positions in the complexes. How these redox cofactors are assembled into the complexes is not known. Cytochrome b, a central catalytic subunit of complex III, contains two heme bs. Here, we unravel the sequence of events in the mitochondrial inner membrane by which cytochrome b is hemylated. Heme incorporation occurs in a strict sequential process that involves interactions of the newly synthesized cytochrome b with assembly factors and structural complex III subunits. These interactions are functionally connected to cofactor acquisition that triggers the progression of cytochrome b through successive assembly intermediates. Failure to hemylate cytochrome b sequesters the Cbp3–Cbp6 complex in early assembly intermediates, thereby causing a reduction in cytochrome b synthesis via a feedback loop that senses hemylation of cytochrome b.

A Single Xyloglucan Xylosyltransferase is Sufficient for Generation of the XXXG Xylosylation Pattern of Xyloglucan

2021 ◽  
Author(s):  
Ruiqin Zhong ◽  
Dennis R Phillips ◽  
Zheng-Hua Ye
Keyword(s):  
Recombinant Proteins ◽  
Cell Walls ◽  
Degree Of Polymerization ◽  
Primary Cell ◽  
Hek293 Cells ◽  
Biochemical Mechanism ◽  
The Third ◽  
Insight Into

Abstarct Xyloglucan is the most abundant hemicellulose in the primary cell walls of dicots. Dicot xyloglucan is the XXXG-type consisting of repeating units of three consecutive xylosylated Glc residues followed by one unsubstituted Glc. Its xylosylation is catalyzed by xyloglucan 6-xylosyltransferases (XXTs) and there exist five XXTs (AtXXT1-5) in Arabidopsis. While AtXXT1and AtXXT2 have been shown to add the first two Xyl residues in the XXXG repeat, which XXTs are responsible for the addition of the third Xyl residue remains elusive although AtXXT5 was a proposed candidate. In this report, we generated recombinant proteins of all five Arabidopsis XXTs and one rice XXT (OsXXT1) in the mammalian HEK293 cells and investigated their ability to sequentially xylosylate Glc residues to generate the XXXG xylosylation pattern. We found that like AtXXT1/2, AtXXT4 and OsXXT1 could efficiently xylosylate the cellohexaose (G6) acceptor to produce mono- and di-xylosylated G6, whereas AtXXT5 was only barely capable of adding one Xyl onto G6. When AtXXT1-catalyzed products were used as acceptors, AtXXT1/2/4 and OsXXT1 but not AtXXT5 were able to xylosylate additional Glc residues to generate tri- and tetra-xylosylated G6. Further characterization of the tri- and tetra-xylosylated G6 revealed that they had the sequence of GXXXGG and GXXXXG with three and four consecutive xylosylated Glc residues, respectively. In addition, we have found that although tri-xylosylation occurred on G6, cello-oligomers with a degree of polymerization of 3 to 5 could only be mono- and di-xylosylated. Together, these results indicate that each of AtXXT1/2/4 and OsXXT1 is capable of sequentially adding Xyl onto three contiguous Glc residues to generate the XXXG xylosylation pattern and these findings provide new insight into the biochemical mechanism underlying xyloglucan biosynthesis.

Complex III Mitochondrial Leukoencephalopathy Masquerading Acute Demyelinating Syndrome Due to a Novel Variant in CYC1

2021 ◽  
Author(s):  
Erfan Heidari ◽  
Maryam Rasoulinezhad ◽  
Neda Pak ◽  
Mahmoud Reza Ashrafi ◽  
Morteza Heidari ◽  
...  
Keyword(s):  
Vision Loss ◽  
Nuclear Dna ◽  
Missense Variant ◽  
Mitochondrial Respiratory Chain ◽  
Complex Iii ◽  
Clinical Spectrum ◽  
Neurological Deficits ◽  
Respiratory Chain Complexes ◽  
Mitochondrial Inner Membrane ◽  
Novel Variant

Abstract Background Complex III (CIII) is the third out of five mitochondrial respiratory chain complexes residing at the mitochondrial inner membrane. The assembly of 10 subunits encoded by nuclear DNA and one by mitochondrial DNA result in the functional CIII which transfers electrons from ubiquinol to cytochrome c. Deficiencies of CIII are among the least investigated mitochondrial disorders and thus clinical spectrum of patients with mutations in CIII is not well defined. Resultswe report on a 10-year-old girl born to consanguineous Iranian parents presenting with acute neurological deficits reminiscent of acquired demyelination, mainly acute bilateral vision loss, who was ultimately confirmed to have a novel homozygous missense variant, c.949C>T; p.(Arg317Trp) in complex III of the mitochondrial chain. Sanger sequencing confirmed the segregation of this variant with disease in the family. ConclusionWe present a patient with a mitochondrial leukoencephalopathy due to complex III deficiency that manifested with features suggestive of an acquired demyelinating syndrome. The effect of this variant on the protein structure was shown in-silico. Our findings, not only expand the clinical spectrum due to defects in CYC1 gene but also highlight that mitochondrial disease should be considered in children with acute CNS demyelination.

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