scholarly journals Rieske head domain dynamics and indazole-derivative inhibition of Candida albicans complex III

2021 ◽  
Author(s):  
Justin Di Trani ◽  
Zhongle Liu ◽  
Luke Whitesell ◽  
Peter Brzezinski ◽  
Leah Cowen ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Electron Transport ◽  
Electron Transport Chain ◽  
Transport Processes ◽  
Complex Iii ◽  
Cellular Respiration ◽  
Inner Mitochondrial Membrane ◽  
Head Domain ◽  
Q Cycle ◽  
Transport Chain

During cellular respiration, electron transfer between the integral membrane protein complexes of the electron transport chain is coupled to proton translocation across the inner mitochondrial membrane, which in turn powers synthesis of ATP and transmembrane transport processes. The homodimeric electron transport chain Complex III (CIII2) oxidizes ubiquinol (UQH2) to ubiquinone (UQ), transferring electrons to cytochrome c, and translocating protons through a mechanism known as the Q cycle. The Q cycle involves UQH2 oxidation and UQ reduction at two different sites within each CIII monomer, as well as movement of the head domain of the Rieske subunit. We used cryoEM to determine the structure of CIII2 from Candida albicans, revealing density for endogenous UQ in the structure and allowing us to directly visualize the continuum of conformations of the Rieske head domain. Analysis of these conformations does not indicate cooperativity in the position of the Rieske head domains or binding of ligands in the two CIIIs of the CIII2 dimer. CryoEM with the indazole derivative Inz-5, which inhibits fungal CIII2 and is fungicidal when administered with fungistatic azole drugs, showed that inhibition by Inz-5 alters the equilibrium of the Rieske head domain positions.

The Electron Transport Chain

2014 ◽  
Vol 76 (7) ◽  
pp. 456-458 ◽  
Author(s):  
Chris Romero ◽  
James Choun
Keyword(s):  
Electron Transport ◽  
Advanced Placement ◽  
Electron Transport Chain ◽  
Cellular Respiration ◽  
College Level ◽  
Inner Mitochondrial Membrane ◽  
College Biology ◽  
Everyday Objects ◽  
Transport Chain ◽  
Introductory College

This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular respiration produces ATP. The activity works best as a supplement after you have already discussed the electron transport chain in lecture but can be used prior to instruction to help students visualize the processes that occur. This demonstration was designed for general college biology for majors at a community college, but it could be used in any introductory college-level or advanced placement biology course.

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

Contribution of leucine 85 to the structure and function of Saccharomyces cerevisiae iso-1 cytochrome c

2001 ◽  
Vol 79 (4) ◽  
pp. 517-524 ◽  
Author(s):  
Jonathan C Parrish ◽  
J Guy Guillemette ◽  
Carmichael JA Wallace
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Electron Transfer ◽  
Electron Transport ◽  
Cytochrome C ◽  
Transport Processes ◽  
Complex Iii ◽  
Side Chain ◽  
Inner Mitochondrial Membrane ◽  
And Function ◽  
First Time

Cytochrome c is a small electron-transport protein whose major role is to transfer electrons between complex III (cytochrome reductase) and complex IV (cytochrome c oxidase) in the inner mitochondrial membrane of eukaryotes. Cytochrome c is used as a model for the examination of protein folding and structure and for the study of biological electron-transport processes. Amongst 96 cytochrome c sequences, residue 85 is generally conserved as either isoleucine or leucine. Spatially, the side chain is associated closely with that of the invariant residue Phe82, and this interaction may be important for optimal cytochrome c activity. The functional role of residue 85 has been examined using six site-directed mutants of Saccharomyces cerevisiae iso-1 cytochrome c, including, for the first time, kinetic data for electron transfer with the principle physiological partners. Results indicate two likely roles for the residue: first, heme crevice resistance to ligand exchange, sensitive to both the hydrophobicity and volume of the side chain; second, modulation of electron-transport activity through maintenance of the hydrophobic character of the protein in the vicinity of Phe82 and the exposed heme edge, and possibly of the ability of this region to facilitate redox-linked conformational change.Key words: protein engineering, cytochrome c, structure-function relations, electron transfer, hydrophobic packing.

scholarly journals A Chemogenomic Screen in Saccharomyces cerevisiae Uncovers a Primary Role for the Mitochondria in Farnesol Toxicity and Its Regulation by the Pkc1 Pathway

2006 ◽  
Vol 282 (7) ◽  
pp. 4868-4874 ◽  
Author(s):  
Gregory D. Fairn ◽  
Kendra MacDonald ◽  
Christopher R. McMaster
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Reactive Oxygen Species ◽  
Cell Death ◽  
Electron Transport ◽  
Signaling Pathway ◽  
Electron Transport Chain ◽  
Reactive Oxygen ◽  
Complex Iii ◽  
Oxygen Species ◽  
Transport Chain

The isoprenoid farnesol has been shown to preferentially induce apoptosis in cancerous cells; however, the mode of action of farnesol-induced death is not established. We used chemogenomic profiling using Saccharomyces cerevisiae to probe the core cellular processes targeted by farnesol. This screen revealed 48 genes whose inactivation increased sensitivity to farnesol. The gene set indicated a role for the generation of oxygen radicals by the Rieske iron-sulfur component of complex III of the electron transport chain as a major mediator of farnesol-induced cell death. Consistent with this, loss of mitochondrial DNA, which abolishes electron transport, resulted in robust resistance to farnesol. A genomic interaction map predicted interconnectedness between the Pkc1 signaling pathway and farnesol sensitivity via regulation of the generation of reactive oxygen species. Consistent with this prediction (i) Pkc1, Bck1, and Mkk1 relocalized to the mitochondria upon farnesol addition, (ii) inactivation of the only non-essential and non-redundant member of the Pkc1 signaling pathway, BCK1, resulted in farnesol sensitivity, and (iii) expression of activated alleles of PKC1, BCK1, and MKK1 increased resistance to farnesol and hydrogen peroxide. Sensitivity to farnesol was not affected by the presence of the osmostabilizer sorbitol nor did farnesol affect phosphorylation of the ultimate Pkc1-responsive kinase responsible for controlling the cell wall integrity pathway, Slt2. The data indicate that the generation of reactive oxygen species by the electron transport chain is a primary mechanism by which farnesol kills cells. The Pkc1 signaling pathway regulates farnesol-mediated cell death through management of the generation of reactive oxygen species.

Activity of complex III of the mitochondrial electron transport chain is essential for early heart muscle cell differentiation

2004 ◽  
Vol 18 (11) ◽  
pp. 1300-1302 ◽  
Author(s):  
Dimitry Spitkovsky ◽  
Philipp Sasse ◽  
Eugen Kolossov ◽  
Cornelia Böttinger ◽  
Bernd K. Fleischmann ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Electron Transport ◽  
Muscle Cell ◽  
Heart Muscle ◽  
Electron Transport Chain ◽  
Complex Iii ◽  
Mitochondrial Electron Transport Chain ◽  
Heart Muscle Cell ◽  
Muscle Cell Differentiation ◽  
Transport Chain

scholarly journals Oxidation and reduction of pyridine nucleotides in alamethicin-permeabilized plant mitochondria

2004 ◽  
Vol 380 (1) ◽  
pp. 193-202 ◽  
Author(s):  
Fredrik I. JOHANSSON ◽  
Agnieszka M. MICHALECKA ◽  
Ian M. MØLLER ◽  
Allan G. RASMUSSON
Keyword(s):  
Electron Transport ◽  
Complex I ◽  
Electron Transport Chain ◽  
Nadh Dehydrogenase ◽  
Plant Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Intact Cells ◽  
Transport Chain ◽  
Invasive Method

The inner mitochondrial membrane is selectively permeable, which limits the transport of solutes and metabolites across the membrane. This constitutes a problem when intramitochondrial enzymes are studied. The channel-forming antibiotic AlaM (alamethicin) was used as a potentially less invasive method to permeabilize mitochondria and study the highly branched electron-transport chain in potato tuber (Solanum tuberosum) and pea leaf (Pisum sativum) mitochondria. We show that AlaM permeabilized the inner membrane of plant mitochondria to NAD(P)H, allowing the quantification of internal NAD(P)H dehydrogenases as well as matrix enzymes in situ. AlaM was found to inhibit the electron-transport chain at the external Ca2+-dependent rotenone-insensitive NADH dehydrogenase and around complexes III and IV. Nevertheless, under optimal conditions, especially complex I-mediated NADH oxidation in AlaM-treated mitochondria was much higher than what has been previously measured by other techniques. Our results also show a difference in substrate specificities for complex I in mitochondria as compared with inside-out submitochondrial particles. AlaM facilitated the passage of cofactors to and from the mitochondrial matrix and allowed the determination of NAD+ requirements of malate oxidation in situ. In summary, we conclude that AlaM provides the best method for quantifying NADH dehydrogenase activities and that AlaM will prove to be an important method to study enzymes under conditions that resemble their native environment not only in plant mitochondria but also in other membrane-enclosed compartments, such as intact cells, chloroplasts and peroxisomes.

scholarly journals Differential remodeling of the electron transport chain is required to support TLR3 and TLR4 signaling and cytokine production in macrophages

2019 ◽  
Author(s):  
Duale Ahmed ◽  
David Roy ◽  
Allison Jaworski ◽  
Alex Edwards ◽  
Alfonso Abizaid ◽  
...  
Keyword(s):  
Electron Transport ◽  
Immune Responses ◽  
Electron Transport Chain ◽  
Cytokine Production ◽  
Critical Role ◽  
Innate Immune ◽  
Fine Tuning ◽  
Complex Iii ◽  
Innate Immune Responses ◽  
Transport Chain

AbstractIncreasing evidence suggests that mitochondria play a critical role in driving innate immune responses against bacteria and viruses. However, it is unclear if differential reprogramming of mitochondrial function contributes to the fine tuning of pathogen specific immune responses. Here, we found that TLR3 and TLR4 engagement on murine bone marrow derived macrophages was associated with differential remodeling of electron transport chain complex expression. This remodeling was associated with differential accumulation of mitochondrial and cytosolic ROS, which were required to support ligand specific inflammatory and antiviral cytokine production. We also found that the magnitude of TLR3, but not TLR4, responses were modulated by glucose availability. Under conditions of low glucose conditions, TLR3 engagement was associated with increased ETC complex III expression, increased mitochondrial and cytosolic ROS and increased inflammatory and antiviral cytokine production. This amplification was selectively reversed by targeting superoxide production from the outer Q-binding site of the ETC complex III. These results suggest that ligand specific modulation of the ETC may act as a rheostat that fine-tunes innate immune responses via mitochondrial ROS production. Modulation of these processes may represent a novel mechanism to modulate the nature as well as the magnitude of antiviral versus inflammatory immune responses.

scholarly journals Differential remodeling of the electron transport chain is required to support TLR3 and TLR4 signaling and cytokine production in macrophages

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Duale Ahmed ◽  
David Roy ◽  
Allison Jaworski ◽  
Alexander Edwards ◽  
Alfonso Abizaid ◽  
...  
Keyword(s):  
Electron Transport ◽  
Immune Responses ◽  
Electron Transport Chain ◽  
Cytokine Production ◽  
Critical Role ◽  
Innate Immune ◽  
Fine Tuning ◽  
Complex Iii ◽  
Innate Immune Responses ◽  
Transport Chain

AbstractIncreasing evidence suggests that mitochondria play a critical role in driving innate immune responses against bacteria and viruses. However, it is unclear if differential reprogramming of mitochondrial function contributes to the fine tuning of pathogen specific immune responses. Here, we found that TLR3 and TLR4 engagement on murine bone marrow derived macrophages was associated with differential remodeling of electron transport chain complex expression. This remodeling was associated with differential accumulation of mitochondrial and cytosolic ROS, which were required to support ligand specific inflammatory and antiviral cytokine production. We also found that the magnitude of TLR3, but not TLR4, responses were modulated by glucose availability. Under conditions of low glucose, TLR3 engagement was associated with increased ETC complex III expression, increased mitochondrial and cytosolic ROS and increased inflammatory and antiviral cytokine production. This amplification was selectively reversed by targeting superoxide production from the outer Q-binding site of the ETC complex III. These results suggest that ligand specific modulation of the ETC may act as a rheostat that fine tunes innate immune responses via mitochondrial ROS production. Modulation of these processes may represent a novel mechanism to modulate the nature as well as the magnitude of antiviral vs. inflammatory immune responses.

The efficiency and plasticity of mitochondrial energy transduction

2005 ◽  
Vol 33 (5) ◽  
pp. 897-904 ◽  
Author(s):  
M.D. Brand
Keyword(s):  
Electron Transport ◽  
Atp Synthase ◽  
Electron Transport Chain ◽  
Uncoupling Protein ◽  
Coupling Efficiency ◽  
Energy Transduction ◽  
Proton Pumping ◽  
Complex Iii ◽  
Proton Pumps ◽  
Transport Chain

Since it was first realized that biological energy transduction involves oxygen and ATP, opinions about the amount of ATP made per oxygen consumed have continually evolved. The coupling efficiency is crucial because it constrains mechanistic models of the electron-transport chain and ATP synthase, and underpins the physiology and ecology of how organisms prosper in a thermodynamically hostile environment. Mechanistically, we have a good model of proton pumping by complex III of the electron-transport chain and a reasonable understanding of complex IV and the ATP synthase, but remain ignorant about complex I. Energy transduction is plastic: coupling efficiency can vary. Whether this occurs physiologically by molecular slipping in the proton pumps remains controversial. However, the membrane clearly leaks protons, decreasing the energy funnelled into ATP synthesis. Up to 20% of the basal metabolic rate may be used to drive this basal leak. In addition, UCP1 (uncoupling protein 1) is used in specialized tissues to uncouple oxidative phosphorylation, causing adaptive thermogenesis. Other UCPs can also uncouple, but are tightly regulated; they may function to decrease coupling efficiency and so attenuate mitochondrial radical production. UCPs may also integrate inputs from different fuels in pancreatic β-cells and modulate insulin secretion. They are exciting potential targets for treatment of obesity, cachexia, aging and diabetes.

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