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Adolph C, Cheung CY, McNeil MB, Jowsey WJ, Williams ZC, Hards K, Harold LK, Aboelela A, Bujaroski RS, Buckley BJ, Tyndall JDA, Li Z, Langer JD, Preiss L, Meier T, Steyn AJC, Rhee KY, Berney M, Kelso MJ, Cook GM. A dual-targeting succinate dehydrogenase and F 1F o-ATP synthase inhibitor rapidly sterilizes replicating and non-replicating Mycobacterium tuberculosis. Cell Chem Biol 2024; 31:683-698.e7. [PMID: 38151019 DOI: 10.1016/j.chembiol.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 09/13/2023] [Accepted: 12/04/2023] [Indexed: 12/29/2023]
Abstract
Mycobacterial bioenergetics is a validated target space for antitubercular drug development. Here, we identify BB2-50F, a 6-substituted 5-(N,N-hexamethylene)amiloride derivative as a potent, multi-targeting bioenergetic inhibitor of Mycobacterium tuberculosis. We show that BB2-50F rapidly sterilizes both replicating and non-replicating cultures of M. tuberculosis and synergizes with several tuberculosis drugs. Target identification experiments, supported by docking studies, showed that BB2-50F targets the membrane-embedded c-ring of the F1Fo-ATP synthase and the catalytic subunit (substrate-binding site) of succinate dehydrogenase. Biochemical assays and metabolomic profiling showed that BB2-50F inhibits succinate oxidation, decreases the activity of the tricarboxylic acid (TCA) cycle, and results in succinate secretion from M. tuberculosis. Moreover, we show that the lethality of BB2-50F under aerobic conditions involves the accumulation of reactive oxygen species. Overall, this study identifies BB2-50F as an effective inhibitor of M. tuberculosis and highlights that targeting multiple components of the mycobacterial respiratory chain can produce fast-acting antimicrobials.
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Affiliation(s)
- Cara Adolph
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1042, New Zealand
| | - Chen-Yi Cheung
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Matthew B McNeil
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1042, New Zealand
| | - William J Jowsey
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1042, New Zealand
| | - Zoe C Williams
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Kiel Hards
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Liam K Harold
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Ashraf Aboelela
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Richard S Bujaroski
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Benjamin J Buckley
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Joel D A Tyndall
- School of Pharmacy, University of Otago, Dunedin 9054, New Zealand
| | - Zhengqiu Li
- School of Pharmacy, Jinan University, Guangzhou, China
| | - Julian D Langer
- Proteomics, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany
| | - Laura Preiss
- Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany
| | - Thomas Meier
- Department of Life Sciences, Imperial College London, Exhibition Road, London SW7 2AZ, UK; Private University in the Principality of Liechtenstein, Triesen, Liechtenstein
| | - Adrie J C Steyn
- Africa Health Research Institute, University of KwaZulu Natal, Durban, KwaZulu, Natal, South Africa; Department of Microbiology, Centers for AIDs Research and Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Kyu Y Rhee
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY 14853, USA; Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Michael Berney
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, NY, USA
| | - Michael J Kelso
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Gregory M Cook
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1042, New Zealand.
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2
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Balderas E, Lee SH, Shankar TS, Yin X, Balynas AM, Kyriakopoulos CP, Selzman CH, Drakos SG, Chaudhuri D. Mitochondria possess a large, non-selective ionic current that is enhanced during cardiac injury. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.15.567241. [PMID: 38014208 PMCID: PMC10680780 DOI: 10.1101/2023.11.15.567241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Mitochondrial ion channels are essential for energy production and cell survival. To avoid depleting the electrochemical gradient used for ATP synthesis, channels so far described in the mitochondrial inner membrane open only briefly, are highly ion-selective, have restricted tissue distributions, or have small currents. Here, we identify a mitochondrial inner membrane conductance that has strikingly different behavior from previously described channels. It is expressed ubiquitously, and transports cations non-selectively, producing a large, up to nanoampere-level, current. The channel does not lead to inner membrane uncoupling during normal physiology because it only becomes active at depolarized voltages. It is inhibited by external Ca2+, corresponding to the intermembrane space, as well as amiloride. This large, ubiquitous, non-selective, amiloride-sensitive (LUNA) current appears most active when expression of the mitochondrial calcium uniporter is minimal, such as in the heart. In this organ, we find that LUNA current magnitude increases two- to threefold in multiple mouse models of injury, an effect also seen in cardiac mitochondria from human patients with heart failure with reduced ejection fraction. Taken together, these features lead us to speculate that LUNA current may arise from an essential protein that acts as a transporter under physiological conditions, but becomes a channel under conditions of mitochondrial stress and depolarization.
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Affiliation(s)
- Enrique Balderas
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Sandra H.J. Lee
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Thirupura S. Shankar
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Xue Yin
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Anthony M. Balynas
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Christos P. Kyriakopoulos
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Craig H. Selzman
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
- Department of Surgery, Division of Cardiothoracic Surgery, University of Utah, Salt Lake City, UT
- U.T.A.H. (Utah Transplant Affiliated Hospitals) Cardiac Transplant Program: University of Utah Healthcare and School of Medicine, Intermountain Medical Center, Salt Lake Veterans Affairs Health Care System, Salt Lake City, UT
| | - Stavros G. Drakos
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
- U.T.A.H. (Utah Transplant Affiliated Hospitals) Cardiac Transplant Program: University of Utah Healthcare and School of Medicine, Intermountain Medical Center, Salt Lake Veterans Affairs Health Care System, Salt Lake City, UT
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT
| | - Dipayan Chaudhuri
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
- U.T.A.H. (Utah Transplant Affiliated Hospitals) Cardiac Transplant Program: University of Utah Healthcare and School of Medicine, Intermountain Medical Center, Salt Lake Veterans Affairs Health Care System, Salt Lake City, UT
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT
- Departments of Biochemistry, Biomedical Engineering, University of Utah, Salt Lake City, UT
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3
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Duque JE, Urbina DL, Vesga LC, Ortiz-Rodríguez LA, Vanegas TS, Stashenko EE, Mendez-Sanchez SC. Insecticidal activity of essential oils from American native plants against Aedes aegypti (Diptera: Culicidae): an introduction to their possible mechanism of action. Sci Rep 2023; 13:2989. [PMID: 36805522 PMCID: PMC9941582 DOI: 10.1038/s41598-023-30046-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 02/15/2023] [Indexed: 02/22/2023] Open
Abstract
Searching for new bioactive molecules to design insecticides is a complex process since pesticides should be highly selective, active against the vector, and bio-safe for humans. Aiming to find natural compounds for mosquito control, we evaluated the insecticidal activity of essential oils (EOs) from 20 American native plants against Aedes aegypti larvae using bioassay, biochemical, and in silico analyses. The highest larvicide activity was exhibited by EOs from Steiractinia aspera (LC50 = 42.4 µg/mL), Turnera diffusa (LC50 = 70.9 µg/mL), Piper aduncum (LC50 = 55.8 µg/mL), Lippia origanoides (chemotype thymol/carvacrol) (LC50 = 61.9 µg/mL), L. origanoides (chemotype carvacrol/thymol) (LC50 = 59.8 µg/mL), Hyptis dilatata (LC50 = 61.1 µg/mL), Elaphandra quinquenervis (LC50 = 61.1 µg/mL), and Calycolpus moritzianus (LC50 = 73.29 µg/mL) after 24 h. This biological activity may be related to the disruption of the electron transport chain through the mitochondrial protein complexes. We hypothesized that the observed EOs' effect is due to their major components, where computational approaches such as homology modeling and molecular docking may suggest the possible binding pose of secondary metabolites that inhibit the mitochondrial enzymes and acetylcholinesterase activity (AChE). Our results provided insights into the possible mechanism of action of EOs and their major compounds for new insecticide designs targeting the mitochondria and AChE activity in A. aegypti for effective and safe insecticide.
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Affiliation(s)
- Jonny E. Duque
- grid.411595.d0000 0001 2105 7207Centro de Investigaciones en Enfermedades Tropicales – Cintrop, Departamento de Ciencias Básicas, Escuela de Medicina, Universidad Industrial de Santander, Parque Tecnológico y de Investigaciones Guatiguará Km 2 El Refugio, Piedecuesta, Colombia
| | - Diana L. Urbina
- grid.411595.d0000 0001 2105 7207Grupo de Investigación en Bioquímica y Microbiología (GIBIM), Escuela de Química, Universidad Industrial de Santander, Bucaramanga, Colombia
| | - Luis C. Vesga
- grid.411595.d0000 0001 2105 7207Grupo de Investigación en Bioquímica y Microbiología (GIBIM), Escuela de Química, Universidad Industrial de Santander, Bucaramanga, Colombia
| | - Luis A. Ortiz-Rodríguez
- grid.411595.d0000 0001 2105 7207Centro de Investigaciones en Enfermedades Tropicales – Cintrop, Departamento de Ciencias Básicas, Escuela de Medicina, Universidad Industrial de Santander, Parque Tecnológico y de Investigaciones Guatiguará Km 2 El Refugio, Piedecuesta, Colombia
| | - Thomas S. Vanegas
- grid.411595.d0000 0001 2105 7207Centro de Investigaciones en Enfermedades Tropicales – Cintrop, Departamento de Ciencias Básicas, Escuela de Medicina, Universidad Industrial de Santander, Parque Tecnológico y de Investigaciones Guatiguará Km 2 El Refugio, Piedecuesta, Colombia
| | - Elena E. Stashenko
- grid.411595.d0000 0001 2105 7207Centro de Investigación en Biomoléculas – CIBIMOL y Centro Nacional de Investigación para la Agroindustrialización de Plantas Aromáticas y Medicinales Tropicales – CENIVAM, Universidad Industrial de Santander, Bucaramanga, Colombia
| | - Stelia C. Mendez-Sanchez
- grid.411595.d0000 0001 2105 7207Grupo de Investigación en Bioquímica y Microbiología (GIBIM), Escuela de Química, Universidad Industrial de Santander, Bucaramanga, Colombia
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4
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Unten Y, Murai M, Koshitaka T, Kitao K, Shirai O, Masuya T, Miyoshi H. Comprehensive understanding of multiple actions of anticancer drug tamoxifen in isolated mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148520. [PMID: 34896079 DOI: 10.1016/j.bbabio.2021.148520] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 10/11/2021] [Accepted: 12/02/2021] [Indexed: 12/13/2022]
Abstract
Tamoxifen has been widely used in the treatment of estrogen receptor (ER)-positive breast cancer, whereas it also exhibits ER-independent anticancer effects in various cancer cell types. As one of the convincing mechanisms underlying the ER-independent effects, induction of apoptosis through mitochondrial dysfunction has been advocated. However, the mechanism of action of tamoxifen even at the isolated mitochondrial level is not fully understood and remains controversial. Here, we attempted to comprehensively understand tamoxifen's multiple actions in isolated rat liver mitochondria through not only revisiting the actions hitherto reported but also conducting originally designed experiments. Using submitochondrial particles, we found that tamoxifen has potential as an inhibitor of both respiratory complex I and ATP synthase. However, these inhibitory effects were not elicited in intact mitochondria, likely because penetration of tamoxifen across the inner mitochondrial membrane is highly restricted owing to its localized positive charge (-N+H(CH3)2). This restricted penetration may also explain why tamoxifen is unable to function as a protonophore-type uncoupler in mitochondria. Moreover, tamoxifen suppressed opening of the mitochondrial permeability transition pore induced by Ca2+ overload through enhancing phosphate uptake into the matrix. The photoaffinity labeling experiments using a photolabile tamoxifen derivative (pTAM1) indicated that pTAM1 specifically binds to voltage-dependent anion channels (VDACs) 1 and 3, which regulate transport of various substances into mitochondria. The binding of tamoxifen to VDAC1 and/or VDAC3 could be responsible for the enhancement of phosphate uptake. Taking all the results together, we consider the principal impairment of mitochondrial functions caused by tamoxifen.
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Affiliation(s)
- Yufu Unten
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Tomoki Koshitaka
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Kotaro Kitao
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Osamu Shirai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Takahiro Masuya
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
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5
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Specific chemical modification explores dynamic structure of the NqrB subunit in Na +-pumping NADH-ubiquinone oxidoreductase from Vibrio cholerae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148432. [PMID: 33932367 DOI: 10.1016/j.bbabio.2021.148432] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 04/20/2021] [Indexed: 12/28/2022]
Abstract
The Na+-pumping NADH-ubiquinone oxidoreductase (Na+-NQR) is a main ion transporter in many pathogenic bacteria. We previously proposed that N-terminal stretch of the NqrB subunit plays an important role in regulating the ubiquinone reaction at the adjacent NqrA subunit in Vibrio cholerae Na+-NQR. However, since approximately three quarters of the stretch (NqrB-Met1-Pro37) was not modeled in an earlier crystallographic study, its structure and function remain unknown. If we can develop a method that enables pinpoint modification of this stretch by functional chemicals (such as spin probes), it could lead to new ways to investigate the unsettled issues. As the first step to this end, we undertook to specifically attach an alkyne group to a lysine located in the stretch via protein-ligand affinity-driven substitution using synthetic ligands NAS-K1 and NAS-K2. The alkyne, once attached, can serve as an "anchor" for connecting functional chemicals via convenient click chemistry. After a short incubation of isolated Na+-NQR with these ligands, alkyne was predominantly incorporated into NqrB. Proteomic analyses in combination with mutagenesis of predicted target lysines revealed that alkyne attaches to NqrB-Lys22 located at the nonmodeled region of the stretch. This study not only achieved the specific modification initially aimed for but also provided valuable information about positioning of the nonmodeled region. For example, the fact that hydrophobic NAS-Ks come into contact with NqrB-Lys22 suggests that the nonmodeled region may orient toward the membrane phase rather than protruding into cytoplasmic medium. This conformation may be essential for regulating the ubiquinone reaction in the adjacent NqrA.
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6
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Zeiler MJ, Melander RJ, Melander C. Second-Generation Meridianin Analogues Inhibit the Formation of Mycobacterium smegmatis Biofilms and Sensitize Polymyxin-Resistant Gram-Negative Bacteria to Colistin. ChemMedChem 2020; 15:1672-1679. [PMID: 32662926 DOI: 10.1002/cmdc.202000438] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Indexed: 11/10/2022]
Abstract
Drug-resistant bacteria are rapidly becoming a significant problem across the globe. One element that factors into this crisis is the role played by bacterial biofilms in the recalcitrance of some infections to the effects of conventional antibiotics. Bacteria within a biofilm are highly tolerant of both antibiotic treatment and host immune responses. Biofilms are implicated in many chronic infections, including tuberculosis, in which they can act as bacterial reservoirs, requiring an arduous antibiotic regimen to eradicate the infection. A separate, compounding problem is that antibiotics once seen as last-resort drugs, such as the polymyxin colistin, are now seeing more frequent usage as resistance to front-line drugs in Gram-negative bacteria becomes more prevalent. The increased use of such antibiotics inevitably leads to an increased frequency of resistance. Drugs that inhibit biofilms and/or act as adjuvants to overcome resistance to existing antibiotics will potentially be an important component of future approaches to antibacterial treatment. We have previously demonstrated that analogues of the meridianin natural product family possess adjuvant and antibiofilm activities. In this study, we explore structural variation of the lead molecule from previous studies, and identify compounds showing both improved biofilm inhibition potency and synergy with colistin.
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Affiliation(s)
- Michael J Zeiler
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Roberta J Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
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Murai M. Exploring the binding pocket of quinone/inhibitors in mitochondrial respiratory complex I by chemical biology approaches. Biosci Biotechnol Biochem 2020; 84:1322-1331. [PMID: 32264779 DOI: 10.1080/09168451.2020.1747974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
NADH-quinone oxidoreductase (respiratory complex I) is a key player in mitochondrial energy metabolism. The enzyme couples electron transfer from NADH to quinone with the translocation of protons across the membrane, providing a major proton-motive force that drives ATP synthesis. Recently, X-ray crystallography and cryo-electron microscopy provided further insights into the structure and functions of the enzyme. However, little is known about the mechanism of quinone reduction, which is a crucial step in the energy coupling process. A variety of complex I inhibitors targeting the quinone-binding site have been indispensable tools for mechanistic studies on the enzyme. Using biorationally designed inhibitor probes, the author has accumulated a large amount of experimental data characterizing the actions of complex I inhibitors. On the basis of comprehensive interpretations of the data, the author reviews the structural features of the binding pocket of quinone/inhibitors in bovine mitochondrial complex I. ABBREVIATIONS ATP: adenosine triphosphate; BODIPY: boron dipyrromethene; complex I: proton-translocating NADH-quinone oxidoreductase; DIBO: dibenzocyclooctyne; EM: electron microscopy; FeS: iron-sulfur; FMN: flavin adenine mononucleotide; LDT: ligand-directed tosylate; NADH: nicotinamide adenine dinucleotide; ROS: reactive oxygen species; SMP: submitochondrial particle; TAMRA: 6-carboxy-N,N,N',N'-tetramethylrhodamine; THF: tetrahydrofuran; TMH: transmembrane helix.
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Affiliation(s)
- Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Kyoto, Japan
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8
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Unten Y, Murai M, Yamamoto T, Watanabe A, Ichimaru N, Aburaya S, Aoki W, Shinohara Y, Miyoshi H. Pentenediol-Type Compounds Specifically Bind to Voltage-Dependent Anion Channel 1 in Saccharomyces cerevisiae Mitochondria. Biochemistry 2019; 58:1141-1154. [PMID: 30657320 DOI: 10.1021/acs.biochem.8b01209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Voltage-dependent anion channel 1 (VDAC1) situated in the outer mitochondrial membrane regulates the transfer of various metabolites and is a key player in mitochondria-mediated apoptosis. Although many small chemicals that modulate the functions of VDAC1 have been reported to date, most, if not all, of them cannot be regarded as specific reagents due to their interactions with other transporters or enzymes. By screening our chemical libraries using isolated Saccharomyces cerevisiae mitochondria, we found pentenediol (PTD)-type compounds (e.g., PTD-023) as new specific inhibitors of VDAC1. PTD-023 inhibited overall ADP-uptake/ATP-release reactions in isolated mitochondria at a single digit μM level. To identify the binding position of PTDs in VDAC1 by visualizing PTD-bound peptides, we conducted ligand-directed tosyl (LDT) chemistry using the synthetic LDT reagent t-PTD-023 derived from the parent PTD-023 in combination with mutagenesis experiments. t-PTD-023 made a covalent bond predominantly and subsidiarily with nucleophilic Cys210 and Cys130, respectively, indicating that PTDs bind to the region interactive with both residues. Site-directed mutations of hydrogen bond-acceptable Asp139 and Glu152 to Ala, which were selected as potential interactive partners of the critical pentenediol moiety based on the presumed binding model of PTDs in VDAC1, resulted in a decrease in susceptibility against PTD-023. This result strongly suggests that PTDs bind to VDAC1 through a specific hydrogen bond with the two residues. The present study is the first to demonstrate the binding position of specific inhibitors of VDAC1 at the amino acid level.
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Affiliation(s)
- Yufu Unten
- Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Sakyo-ku, Kyoto 606-8502 , Japan
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Sakyo-ku, Kyoto 606-8502 , Japan
| | - Takenori Yamamoto
- Institute for Genome Research , University of Tokushima , Kuramotocho-3 , Tokushima 770-8503 , Japan
| | - Akira Watanabe
- Institute for Genome Research , University of Tokushima , Kuramotocho-3 , Tokushima 770-8503 , Japan
| | - Naoya Ichimaru
- Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Sakyo-ku, Kyoto 606-8502 , Japan
| | - Shunsuke Aburaya
- Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Sakyo-ku, Kyoto 606-8502 , Japan
| | - Wataru Aoki
- Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Sakyo-ku, Kyoto 606-8502 , Japan
| | - Yasuo Shinohara
- Institute for Genome Research , University of Tokushima , Kuramotocho-3 , Tokushima 770-8503 , Japan
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Sakyo-ku, Kyoto 606-8502 , Japan
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9
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Uno S, Kimura H, Murai M, Miyoshi H. Exploring the quinone/inhibitor-binding pocket in mitochondrial respiratory complex I by chemical biology approaches. J Biol Chem 2018; 294:679-696. [PMID: 30425100 DOI: 10.1074/jbc.ra118.006056] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 11/10/2018] [Indexed: 11/06/2022] Open
Abstract
NADH-quinone oxidoreductase (respiratory complex I) couples NADH-to-quinone electron transfer to the translocation of protons across the membrane. Even though the architecture of the quinone-access channel in the enzyme has been modeled by X-ray crystallography and cryo-EM, conflicting findings raise the question whether the models fully reflect physiologically relevant states present throughout the catalytic cycle. To gain further insights into the structural features of the binding pocket for quinone/inhibitor, we performed chemical biology experiments using bovine heart sub-mitochondrial particles. We synthesized ubiquinones that are oversized (SF-UQs) or lipid-like (PC-UQs) and are highly unlikely to enter and transit the predicted narrow channel. We found that SF-UQs and PC-UQs can be catalytically reduced by complex I, albeit only at moderate or low rates. Moreover, quinone-site inhibitors completely blocked the catalytic reduction and the membrane potential formation coupled to this reduction. Photoaffinity-labeling experiments revealed that amiloride-type inhibitors bind to the interfacial domain of multiple core subunits (49 kDa, ND1, and PSST) and the 39-kDa supernumerary subunit, although the latter does not make up the channel cavity in the current models. The binding of amilorides to the multiple target subunits was remarkably suppressed by other quinone-site inhibitors and SF-UQs. Taken together, the present results are difficult to reconcile with the current channel models. On the basis of comprehensive interpretations of the present results and of previous findings, we discuss the physiological relevance of these models.
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Affiliation(s)
- Shinpei Uno
- From the Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Hironori Kimura
- From the Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Masatoshi Murai
- From the Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Hideto Miyoshi
- From the Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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10
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Aoyama A, Murai M, Ichimaru N, Aburaya S, Aoki W, Miyoshi H. Epoxycyclohexenedione-Type Compounds Make Up a New Class of Inhibitors of the Bovine Mitochondrial ADP/ATP Carrier. Biochemistry 2018; 57:1031-1044. [PMID: 29313673 DOI: 10.1021/acs.biochem.7b01119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Through the extensive screening of our chemical library, we found epoxycyclohexenedione (ECHD)-type compounds (AMM-59 and -120) as unique inhibitors of the bovine heart mitochondrial ADP/ATP carrier (AAC). This study investigated the mechanism of inhibition of AAC by ECHDs using submitochondrial particles (SMPs). Proteomic analyses of ECHD-bound AAC as well as biochemical characterization using different SH reagents showed that ECHDs inhibit the function of AAC by covalently binding primarily to Cys57 and secondarily to Cys160. Interestingly, AAC remarkably aggregated in SMPs upon being incubated with high concentrations of ECHDs for a long period of time. This aggregation was observed under both oxidative and reductive conditions of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of SMP proteins, indicating that aggregation is not caused by intermolecular S-S linkages. ECHDs are the first chemicals, to the best of our knowledge, to induce prominent structural alteration in AAC without forming intermolecular S-S linkages. When all solvent-accessible cysteines (Cys57, Cys160, and Cys257) were previously modified by N-ethylmaleimide, the aggregation of AAC was completely suppressed. In contrast, when Cys57 or Cys160 is selectively modified by a SH reagent, the covalent binding of ECHDs to a residual free residue of the two cysteines is sufficient to induce aggregation. The aggregation-inducing ability of another ECHD analogue (AMM-124), which has an alkyl chain that is shorter than those of AMM-59 and -120, was significantly less efficient than that of the two compounds. On the basis of these results, the mechanism underlying the aggregation of AAC induced by ECHDs is discussed.
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Affiliation(s)
- Ayaki Aoyama
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
| | - Naoya Ichimaru
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
| | - Shunsuke Aburaya
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
| | - Wataru Aoki
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
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11
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Masuya T, Murai M, Ito T, Aburaya S, Aoki W, Miyoshi H. Pinpoint Chemical Modification of the Quinone-Access Channel of Mitochondrial Complex I via a Two-Step Conjugation Reaction. Biochemistry 2017; 56:4279-4287. [DOI: 10.1021/acs.biochem.7b00612] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Takahiro Masuya
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Masatoshi Murai
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Takeshi Ito
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Shunsuke Aburaya
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Wataru Aoki
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Hideto Miyoshi
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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12
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Kim J, You YJ. Regulation of organelle function by metformin. IUBMB Life 2017; 69:459-469. [PMID: 28444922 DOI: 10.1002/iub.1633] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/02/2017] [Indexed: 12/30/2022]
Abstract
Metformin ameliorates hyperglycemia without the side effects of lactic acidosis or hypoglycemia. Metformin lowers the blood glucose level by decreasing hepatic glucose production in the liver and by increasing glucose uptake in the muscle. Recent studies show that metformin induces cell death in certain cancer cell lines by interfering with the metabolism of the cancer cells. Therefore, understanding the mechanisms of action for metformin will provide insights into how to better treat diabetes and other metabolic disorders and also into the development of new therapeutic drugs. One of the best understood molecular targets of metformin is the mitochondrial complex I. However, given metformin's broad effects on metabolism, it could act on multiple targets. In this review, we summarize current findings in metformin's mechanisms of action regarding its known targets in mitochondria and known effects in cancer cell lines. Then, we introduce endosomal Na+ /H+ exchangers and the V-ATPase as new potential targets of metformin's action. Finally, we will discuss the hypothesis that metformin directly acts on endosome/lysosome regulation so as to regulate metabolism and ultimately alleviate type 2 diabetes. © 2017 IUBMB Life, 69(7):459-469, 2017.
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Affiliation(s)
- Jeongho Kim
- Department of Biological Sciences, Inha University, Incheon, South Korea
| | - Young-Jai You
- Nagoya Research Center for Brain and Neural Circuits, Graduate School of Science, Nagoya University, Nagoya, Japan
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13
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Kohiki T, Kato Y, Nishikawa Y, Yorita K, Sagawa I, Denda M, Inokuma T, Shigenaga A, Fukui K, Otaka A. Elucidation of inhibitor-binding pockets ofd-amino acid oxidase using docking simulation and N-sulfanylethylanilide-based labeling technology. Org Biomol Chem 2017; 15:5289-5297. [DOI: 10.1039/c7ob00633k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Binding pockets of a schizophrenia-relatedd-amino acid oxidase to its inhibitor were clarified by docking simulation and protein labeling experiments.
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Affiliation(s)
- Taiki Kohiki
- Institute of Biomedical Sciences and Graduate School of Pharmaceutical Sciences
- Tokushima University
- Tokushima 770-8505
- Japan
| | - Yusuke Kato
- Division of Enzyme Pathophysiology
- The Institute for Enzyme Research (KOSOKEN)
- Tokushima University
- Tokushima 770-8503
- Japan
| | - Yusuke Nishikawa
- Institute of Biomedical Sciences and Graduate School of Pharmaceutical Sciences
- Tokushima University
- Tokushima 770-8505
- Japan
| | - Kazuko Yorita
- Division of Enzyme Pathophysiology
- The Institute for Enzyme Research (KOSOKEN)
- Tokushima University
- Tokushima 770-8503
- Japan
| | - Ikuko Sagawa
- Support Center for Advanced Medical Sciences
- Institute of Biomedical Sciences
- Tokushima University Graduate School
- Tokushima 770-8505
- Japan
| | - Masaya Denda
- Institute of Biomedical Sciences and Graduate School of Pharmaceutical Sciences
- Tokushima University
- Tokushima 770-8505
- Japan
| | - Tsubasa Inokuma
- Institute of Biomedical Sciences and Graduate School of Pharmaceutical Sciences
- Tokushima University
- Tokushima 770-8505
- Japan
| | - Akira Shigenaga
- Institute of Biomedical Sciences and Graduate School of Pharmaceutical Sciences
- Tokushima University
- Tokushima 770-8505
- Japan
- PRESTO
| | - Kiyoshi Fukui
- Division of Enzyme Pathophysiology
- The Institute for Enzyme Research (KOSOKEN)
- Tokushima University
- Tokushima 770-8503
- Japan
| | - Akira Otaka
- Institute of Biomedical Sciences and Graduate School of Pharmaceutical Sciences
- Tokushima University
- Tokushima 770-8505
- Japan
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14
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Murai M, Inaoka H, Masuya T, Aburaya S, Aoki W, Miyoshi H. Specific Methylation of Asp160 (49 kDa subunit) Located inside the Quinone Binding Cavity of Bovine Mitochondrial Complex I. Biochemistry 2016; 55:3189-97. [DOI: 10.1021/acs.biochem.6b00190] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Masatoshi Murai
- Division of Applied Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Hiroyuki Inaoka
- Division of Applied Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Takahiro Masuya
- Division of Applied Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Shunsuke Aburaya
- Division of Applied Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Wataru Aoki
- Division of Applied Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Hideto Miyoshi
- Division of Applied Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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15
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Masuya T, Okuda K, Murai M, Miyoshi H. Characterization of the reaction of decoupling ubiquinone with bovine mitochondrial respiratory complex I. Biosci Biotechnol Biochem 2016; 80:1464-9. [PMID: 27140857 DOI: 10.1080/09168451.2016.1179095] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We previously produced the unique ubiquinone QT ("decoupling" quinone), the catalytic reduction of which in NADH-quinone oxidoreduction with bovine heart mitochondrial NADH-ubiquinone oxidoreductase (complex I) is completely decoupled from proton translocation across the membrane domain. This feature is markedly distinct from those of typical short-chain quinones such as ubiquinone-1. To further characterize the features of the QT reaction with complex I, we herein synthesized three QT analogs, QT2-QT4, and characterized their electron transfer reactions. We found that all aspects of electron transfer (e.g. electron-accepting activity and membrane potential formation) vary significantly among these analogs. The features of QT2 as decoupling quinone were slightly superior to those of original QT. Based on these results, we conclude that the bound positions of QTs within the quinone binding cavity susceptibly change depending on their side-chain structures, and the positions, in turn, govern the behavior of QTs as electron acceptors.
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Affiliation(s)
- Takahiro Masuya
- a Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Sakyo-ku, Kyoto , Japan
| | - Kenji Okuda
- a Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Sakyo-ku, Kyoto , Japan
| | - Masatoshi Murai
- a Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Sakyo-ku, Kyoto , Japan
| | - Hideto Miyoshi
- a Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Sakyo-ku, Kyoto , Japan
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16
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Jones AJY, Blaza JN, Bridges HR, May B, Moore AL, Hirst J. A Self-Assembled Respiratory Chain that Catalyzes NADH Oxidation by Ubiquinone-10 Cycling between Complex I and the Alternative Oxidase. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201507332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Okuda K, Murai M, Aburaya S, Aoki W, Miyoshi H. Reduction of Synthetic Ubiquinone QT Catalyzed by Bovine Mitochondrial Complex I Is Decoupled from Proton Translocation. Biochemistry 2016; 55:470-81. [PMID: 26701224 DOI: 10.1021/acs.biochem.5b01090] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We previously succeeded in site-specific chemical modifications of the inner part of the quinone binding pocket of bovine mitochondrial complex I through ligand-directed tosylate (LDT) chemistry using specific inhibitors as high-affinity ligands for the enzyme [Masuya, T., et al. (2014) Biochemistry 53, 2304-2317, 7816-7823]. To investigate whether a short-chain ubiquinone, in place of these specific inhibitors, serves as a ligand for LDT chemistry, we herein synthesized a LDT reagent QT possessing ubiquinone scaffold and performed LDT chemistry with bovine heart submitochondrial particles (SMP). Detailed proteomic analyses revealed that QT properly guides the tosylate group into the quinone binding pocket and transfers a terminal alkyne to nucleophilic amino acids His150 and Asp160 in the 49 kDa subunit. This result clearly indicates that QT occupies the inner part of the quinone binding pocket. Nevertheless, we noted that QT is a unique electron acceptor from complex I distinct from typical short-chain ubiquinones such as ubiquinone-1 (Q1) for several reasons; for example, QT reduction in NADH-QT oxidoreduction was almost completely insensitive to quinone-site inhibitors (such as bullatacin and piericidin A), and this reaction did not produce a membrane potential. On the basis of detailed comparisons of the electron transfer features between QT and typical short-chain quinones, we conclude that QT may accept electrons from an N2 cluster at a position different from that of typical short-chain quinones because of its unique side-chain structure; accordingly, QT reduction is unable to induce putative structural changes inside the quinone binding pocket, which are critical for driving proton translocation. Thus, QT is the first ubiquinone analogue, to the best of our knowledge, the catalytic reduction of which is decoupled from proton translocation through the membrane domain. Implications for mechanistic studies on QT are also discussed.
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Affiliation(s)
- Kenji Okuda
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
| | - Shunsuke Aburaya
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
| | - Wataru Aoki
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan
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18
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Current topics on inhibitors of respiratory complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:884-91. [PMID: 26625959 DOI: 10.1016/j.bbabio.2015.11.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 10/26/2015] [Accepted: 11/17/2015] [Indexed: 12/12/2022]
Abstract
There are a variety of chemicals which regulate the functions of bacterial and mitochondrial complex I. Some of them, such as rotenone and piericidin A, have been indispensable molecular tools in mechanistic studies on complex I. A large amount of experimental data characterizing the actions of complex I inhibitors has been accumulated so far. Recent X-ray crystallographic structural models of entire complex I may be helpful to carefully interpret this data. We herein focused on recent hot topics on complex I inhibitors and the subjects closely connected to these inhibitors, which may provide useful information not only on the structural and functional aspects of complex I, but also on drug design targeting this enzyme. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt.
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19
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Jones AJY, Blaza JN, Bridges HR, May B, Moore AL, Hirst J. A Self-Assembled Respiratory Chain that Catalyzes NADH Oxidation by Ubiquinone-10 Cycling between Complex I and the Alternative Oxidase. Angew Chem Int Ed Engl 2015; 55:728-31. [PMID: 26592861 PMCID: PMC4954055 DOI: 10.1002/anie.201507332] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/28/2015] [Indexed: 12/05/2022]
Abstract
Complex I is a crucial respiratory enzyme that conserves the energy from NADH oxidation by ubiquinone‐10 (Q10) in proton transport across a membrane. Studies of its energy transduction mechanism are hindered by the extreme hydrophobicity of Q10, and they have so far relied on native membranes with many components or on hydrophilic Q10 analogues that partition into membranes and undergo side reactions. Herein, we present a self‐assembled system without these limitations: proteoliposomes containing mammalian complex I, Q10, and a quinol oxidase (the alternative oxidase, AOX) to recycle Q10H2 to Q10. AOX is present in excess, so complex I is completely rate determining and the Q10 pool is kept oxidized under steady‐state catalysis. The system was used to measure a fully‐defined KM value for Q10. The strategy is suitable for any enzyme with a hydrophobic quinone/quinol substrate, and could be used to characterize hydrophobic inhibitors with potential applications as pharmaceuticals, pesticides, or fungicides.
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Affiliation(s)
- Andrew J Y Jones
- Medical Research Council Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY (UK)
| | - James N Blaza
- Medical Research Council Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY (UK)
| | - Hannah R Bridges
- Medical Research Council Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY (UK)
| | - Benjamin May
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG (UK)
| | - Anthony L Moore
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG (UK)
| | - Judy Hirst
- Medical Research Council Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY (UK).
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