1
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Janczak M, Vilhjálmsdóttir J, Ädelroth P. Proton transfer in cytochrome bd-I from E. coli involves Asp-105 in CydB. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2024; 1865:149489. [PMID: 39009175 DOI: 10.1016/j.bbabio.2024.149489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 06/27/2024] [Indexed: 07/17/2024]
Abstract
Cytochrome bds are bacterial terminal oxidases expressed under low oxygen conditions, and they are important for the survival of many pathogens and hence potential drug targets. The largest subunit CydA contains the three redox-active cofactors heme b558, heme b595 and the active site heme d. One suggested proton transfer pathway is found at the interface between the CydA and the other major subunit CydB. Here we have studied the O2 reduction mechanism in E. coli cyt. bd-I using the flow-flash technique and focused on the mechanism, kinetics and pathway for proton transfer. Our results show that the peroxy (P) to ferryl (F) transition, coupled to the oxidation of the low-spin heme b558 is pH dependent, with a maximum rate constant (~104 s-1) that is slowed down at higher pH. We assign this behavior to rate-limitation by internal proton transfer from a titratable residue with pKa ~ 9.7. Proton uptake from solution occurs with the same P➔F rate constant. Site-directed mutagenesis shows significant effects on catalytic turnover in the CydB variants Asp58B➔Asn and Asp105B➔Asn variants consistent with them playing a role in proton transfer. Furthermore, in the Asp105B➔Asn variant, the reactions up to P formation occur essentially as in the wildtype bd-I, but the P➔F transition is specifically inhibited, supporting a direct and specific role for Asp105B in the functional proton transfer pathway in bd-I. We further discuss the possible identity of the high pKa proton donor, and the conservation pattern of the Asp-105B in the cyt. bd superfamily.
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Affiliation(s)
- M Janczak
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - J Vilhjálmsdóttir
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - P Ädelroth
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
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2
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Seitz C, Ahn SH, Wei H, Kyte M, Cook GM, Krause KL, McCammon JA. Targeting Tuberculosis: Novel Scaffolds for Inhibiting Cytochrome bd Oxidase. J Chem Inf Model 2024; 64:5232-5241. [PMID: 38874541 DOI: 10.1021/acs.jcim.4c00344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Discovered in the 1920s, cytochrome bd is a terminal oxidase that has received renewed attention as a drug target since its atomic structure was first determined in 2016. Only found in prokaryotes, we study it here as a drug target for Mycobacterium tuberculosis (Mtb). Most previous drug discovery efforts toward cytochrome bd have involved analogues of the canonical substrate quinone, known as Aurachin D. Here, we report six new cytochrome bd inhibitor scaffolds determined from a computational screen and confirmed on target activity through in vitro testing. These scaffolds provide new avenues for lead optimization toward Mtb therapeutics.
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Affiliation(s)
- Christian Seitz
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Surl-Hee Ahn
- Department of Chemical Engineering, University of California, Davis, Davis, California 95616, United States
| | - Haixin Wei
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Matson Kyte
- Department of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand
| | - Gregory M Cook
- Department of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand
| | - Kurt L Krause
- Department of Biochemistry, University of Otago, Dunedin 9016, New Zealand
| | - J Andrew McCammon
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, United States
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3
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Saha P, Das S, Indurthi HK, Kumar R, Roy A, Kalia NP, Sharma DK. Cytochrome bd oxidase: an emerging anti-tubercular drug target. RSC Med Chem 2024; 15:769-787. [PMID: 38516593 PMCID: PMC10953478 DOI: 10.1039/d3md00587a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 01/25/2024] [Indexed: 03/23/2024] Open
Abstract
Cytochrome bd (cyt-bd) oxidase, one of the two terminal oxidases in the Mycobacterium tuberculosis (Mtb) oxidative phosphorylation pathway, plays an indispensable role in maintaining the functionality of the metabolic pathway under stressful conditions. However, the absence of this oxidase in eukaryotic cells allows researchers to select it as a potential drug target for the synthesis of anti-tubercular (anti-TB) molecules. Cyt-bd inhibitors have often been combined with cytochrome bcc/aa3 super-complex inhibitors in anti-TB drug regimens to achieve a desired bactericidal response. The functional redundancy between both the terminal oxidases is responsible for this. The cryo-EM structure of cyt-bd oxidase from Mtb (PDB ID: 7NKZ) further accelerated the research to identify its inhibitor. Herein, we have summarized the reported anti-TB cyt-bd inhibitors, insight into the rationale behind targeting cyt-bd oxidase, and an outline of the architecture of Mtb cyt-bd oxidase.
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Affiliation(s)
- Pallavi Saha
- Department of Pharmaceutical Engg. and Tech, IIT-Banaras Hindu University Varanasi UP 221005 India
| | - Samarpita Das
- Department of Pharmaceutical Engg. and Tech, IIT-Banaras Hindu University Varanasi UP 221005 India
| | - Harish K Indurthi
- Department of Pharmaceutical Engg. and Tech, IIT-Banaras Hindu University Varanasi UP 221005 India
| | - Rohit Kumar
- Department of Pharmaceutical Engg. and Tech, IIT-Banaras Hindu University Varanasi UP 221005 India
| | - Arnab Roy
- Department of Pharmacology and Toxicology, NIPER-Hyderabad Hyderabad 500037 India
| | - Nitin Pal Kalia
- Department of Pharmacology and Toxicology, NIPER-Hyderabad Hyderabad 500037 India
| | - Deepak K Sharma
- Department of Pharmaceutical Engg. and Tech, IIT-Banaras Hindu University Varanasi UP 221005 India
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4
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Harden SA, Courbon GM, Liang Y, Kim AS, Rubinstein JL. A simple assay for inhibitors of mycobacterial oxidative phosphorylation. J Biol Chem 2024; 300:105483. [PMID: 37992805 PMCID: PMC10770618 DOI: 10.1016/j.jbc.2023.105483] [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: 08/08/2023] [Revised: 10/26/2023] [Accepted: 11/15/2023] [Indexed: 11/24/2023] Open
Abstract
Oxidative phosphorylation, the combined activities of the electron transport chain (ETC) and ATP synthase, has emerged as a valuable target for antibiotics to treat infection with Mycobacterium tuberculosis and related pathogens. In oxidative phosphorylation, the ETC establishes a transmembrane electrochemical proton gradient that powers ATP synthesis. Monitoring oxidative phosphorylation with luciferase-based detection of ATP synthesis or measurement of oxygen consumption can be technically challenging and expensive. These limitations reduce the utility of these methods for characterization of mycobacterial oxidative phosphorylation inhibitors. Here, we show that fluorescence-based measurement of acidification of inverted membrane vesicles (IMVs) can detect and distinguish between inhibition of the ETC, inhibition of ATP synthase, and nonspecific membrane uncoupling. In this assay, IMVs from Mycobacterium smegmatis are acidified either through the activity of the ETC or ATP synthase, the latter modified genetically to allow it to serve as an ATP-driven proton pump. Acidification is monitored by fluorescence from 9-amino-6-chloro-2-methoxyacridine, which accumulates and quenches in acidified IMVs. Nonspecific membrane uncouplers prevent both succinate- and ATP-driven IMV acidification. In contrast, the ETC Complex III2IV2 inhibitor telacebec (Q203) prevents succinate-driven acidification but not ATP-driven acidification, and the ATP synthase inhibitor bedaquiline prevents ATP-driven acidification but not succinate-driven acidification. We use the assay to show that, as proposed previously, lansoprazole sulfide is an inhibitor of Complex III2IV2, whereas thioridazine uncouples the mycobacterial membrane nonspecifically. Overall, the assay is simple, low cost, and scalable, which will make it useful for identifying and characterizing new mycobacterial oxidative phosphorylation inhibitors.
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Affiliation(s)
- Serena A Harden
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Gautier M Courbon
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Medical Biophysics, The University of Toronto, Toronto, Ontario, Canada
| | - Yingke Liang
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, The University of Toronto, Toronto, Ontario, Canada
| | - Angelina S Kim
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, The University of Toronto, Toronto, Ontario, Canada
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Medical Biophysics, The University of Toronto, Toronto, Ontario, Canada; Department of Biochemistry, The University of Toronto, Toronto, Ontario, Canada.
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5
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Zhu C, Shi Y, Yu J, Zhao W, Li L, Liang J, Yang X, Zhang B, Zhao Y, Gao Y, Chen X, Yang X, Zhang L, Guddat LW, Liu L, Yang H, Rao Z, Li J. Cryo-EM structures of a prokaryotic heme transporter CydDC. Protein Cell 2023; 14:919-923. [PMID: 37144855 PMCID: PMC10691846 DOI: 10.1093/procel/pwad022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/12/2023] [Accepted: 04/17/2023] [Indexed: 05/06/2023] Open
Affiliation(s)
- Chen Zhu
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- National Clinical Research Center for Infectious Disease, Shenzhen Third People’s Hospital, Shenzhen 518112, China
| | - Yanfeng Shi
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jing Yu
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Wenhao Zhao
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Lingqiao Li
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jingxi Liang
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300353, China
| | - Xiaolin Yang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- National Clinical Research Center for Infectious Disease, Shenzhen Third People’s Hospital, Shenzhen 518112, China
| | - Bing Zhang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yao Zhao
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- National Clinical Research Center for Infectious Disease, Shenzhen Third People’s Hospital, Shenzhen 518112, China
| | - Yan Gao
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiaobo Chen
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiuna Yang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Lu Zhang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Luke W Guddat
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Lei Liu
- National Clinical Research Center for Infectious Disease, Shenzhen Third People’s Hospital, Shenzhen 518112, China
| | - Haitao Yang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Zihe Rao
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- National Clinical Research Center for Infectious Disease, Shenzhen Third People’s Hospital, Shenzhen 518112, China
- Laboratory of Structural Biology, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300353, China
- Innovative Center for Pathogen Research, Guangzhou Laboratory, Guangzhou 510005, China
| | - Jun Li
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- National Clinical Research Center for Infectious Disease, Shenzhen Third People’s Hospital, Shenzhen 518112, China
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6
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Huynh JQ, Lowder EP, Kranz RG. Structural basis of membrane machines that traffick and attach heme to cytochromes. J Biol Chem 2023; 299:105332. [PMID: 37827288 PMCID: PMC10663686 DOI: 10.1016/j.jbc.2023.105332] [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: 08/31/2023] [Revised: 10/04/2023] [Accepted: 10/06/2023] [Indexed: 10/14/2023] Open
Abstract
We evaluate cryoEM and crystal structures of two molecular machines that traffick heme and attach it to cytochrome c (cyt c), the second activity performed by a cyt c synthase. These integral membrane proteins, CcsBA and CcmF/H, both covalently attach heme to cyt c, but carry it out via different mechanisms. A CcsB-CcsA complex transports heme through a channel to its external active site, where it forms two thioethers between reduced (Fe+2) heme and CysXxxXxxCysHis in cyt c. The active site is formed by a periplasmic WWD sequence and two histidines (P-His1 and P-His2). We evaluate each proposed functional domain in CcsBA cryoEM densities, exploring their presence in other CcsB-CcsA proteins from a wide distribution of organisms (e.g., from Gram positive to Gram negative bacteria to chloroplasts.) Two conserved pockets, for the first and second cysteines of CXXCH, explain stereochemical heme attachment. In addition to other universal features, a conserved periplasmic beta stranded structure, called the beta cap, protects the active site when external heme is not present. Analysis of CcmF/H, here called an oxidoreductase and cyt c synthase, addresses mechanisms of heme access and attachment. We provide evidence that CcmF/H receives Fe+3 heme from holoCcmE via a periplasmic entry point in CcmF, whereby heme is inserted directly into a conserved WWD/P-His domain from above. Evidence suggests that CcmF acts as a heme reductase, reducing holoCcmE (to Fe+2) through a transmembrane electron transfer conduit, which initiates a complicated series of events at the active site.
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Affiliation(s)
- Jonathan Q Huynh
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | - Ethan P Lowder
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | - Robert G Kranz
- Department of Biology, Washington University, St. Louis, Missouri, USA.
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7
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Kelam LM, Wani MA, Dhaked DK. An update on ATP synthase inhibitors: A unique target for drug development in M. tuberculosis. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 180-181:87-104. [PMID: 37105260 DOI: 10.1016/j.pbiomolbio.2023.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 04/21/2023] [Accepted: 04/24/2023] [Indexed: 04/29/2023]
Abstract
ATP synthase is a key protein in the oxidative phosphorylation process, as it aids in the effective production of ATP (Adenosine triphosphate) in all life's of kingdoms. ATP synthases have distinctive properties that contribute to efficient ATP synthesis. The ATP synthase of mycobacterium is of special relevance since it has been identified as a target for potential anti-TB molecules, especially Bedaquiline (BDQ). Better knowledge of how mycobacterial ATP synthase functions and its peculiar characteristics will aid in our understanding of bacterial energy metabolism adaptations. Furthermore, identifying and understanding the important distinctions between human ATP synthase and bacterial ATP synthase may provide insight into the design and development of inhibitors that target specific ATP synthase. In recent years, many potential candidates targeting the ATP synthase of mycobacterium have been developed. In this review, we discuss the druggable targets of the Electron transport chain (ETC) and recently identified potent inhibitors (including clinical molecules) from 2015 to 2022 of diverse classes that target ATP synthase of M. tuberculosis.
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Affiliation(s)
- Lakshmi Mounika Kelam
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER)-Kolkata, Chunilal Bhawan, 168 Maniktala Main Road, Kolkata, 700054, West Bengal, India
| | - Mushtaq Ahmad Wani
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER)-Kolkata, Chunilal Bhawan, 168 Maniktala Main Road, Kolkata, 700054, West Bengal, India
| | - Devendra K Dhaked
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER)-Kolkata, Chunilal Bhawan, 168 Maniktala Main Road, Kolkata, 700054, West Bengal, India.
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8
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Wu D, Mehdipour AR, Finke F, Goojani HG, Groh RR, Grund TN, Reichhart TMB, Zimmermann R, Welsch S, Bald D, Shepherd M, Hummer G, Safarian S. Dissecting the conformational complexity and mechanism of a bacterial heme transporter. Nat Chem Biol 2023:10.1038/s41589-023-01314-5. [PMID: 37095238 PMCID: PMC10374445 DOI: 10.1038/s41589-023-01314-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 03/14/2023] [Indexed: 04/26/2023]
Abstract
Iron-bound cyclic tetrapyrroles (hemes) are redox-active cofactors in bioenergetic enzymes. However, the mechanisms of heme transport and insertion into respiratory chain complexes remain unclear. Here, we used cellular, biochemical, structural and computational methods to characterize the structure and function of the heterodimeric bacterial ABC transporter CydDC. We provide multi-level evidence that CydDC is a heme transporter required for functional maturation of cytochrome bd, a pharmaceutically relevant drug target. Our systematic single-particle cryogenic-electron microscopy approach combined with atomistic molecular dynamics simulations provides detailed insight into the conformational landscape of CydDC during substrate binding and occlusion. Our simulations reveal that heme binds laterally from the membrane space to the transmembrane region of CydDC, enabled by a highly asymmetrical inward-facing CydDC conformation. During the binding process, heme propionates interact with positively charged residues on the surface and later in the substrate-binding pocket of the transporter, causing the heme orientation to rotate 180°.
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Affiliation(s)
- Di Wu
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt/Main, Germany
| | - Ahmad R Mehdipour
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt/Main, Germany
- Center for Molecular Modeling (CMM), Ghent University, Zwijnaarde, Belgium
| | - Franziska Finke
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt/Main, Germany
| | - Hojjat G Goojani
- Amsterdam Institute for Life and Environment (A-LIFE), AIMMS, Faculty of Science, Vrije University of Amsterdam, Amsterdam, the Netherlands
| | - Roan R Groh
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt/Main, Germany
| | - Tamara N Grund
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt/Main, Germany
| | - Thomas M B Reichhart
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt/Main, Germany
| | - Rita Zimmermann
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt/Main, Germany
| | - Sonja Welsch
- Central Electron Microscopy Facility, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Dirk Bald
- Amsterdam Institute for Life and Environment (A-LIFE), AIMMS, Faculty of Science, Vrije University of Amsterdam, Amsterdam, the Netherlands
| | - Mark Shepherd
- School of Biosciences, RAPID Group, University of Kent, Canterbury, UK
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt/Main, Germany
- Institute of Biophysics, Goethe University Frankfurt, Frankfurt/Main, Germany
| | - Schara Safarian
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt/Main, Germany.
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Frankfurt/Main, Germany.
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9
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Makarchuk I, Kägi J, Gerasimova T, Wohlwend D, Friedrich T, Melin F, Hellwig P. pH-dependent kinetics of NO release from E. coli bd-I and bd-II oxidase reveals involvement of Asp/Glu58 B. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148952. [PMID: 36535430 DOI: 10.1016/j.bbabio.2022.148952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 12/06/2022] [Accepted: 12/09/2022] [Indexed: 12/23/2022]
Abstract
Escherichia coli contains two cytochrome bd oxidases, bd-I and bd-II. The structure of both enzymes is highly similar, but they exhibit subtle differences such as the accessibility of the active site through a putative proton channel. Here, we demonstrate that the duroquinol:dioxygen oxidoreductase activity of bd-I increased with alkaline pH, whereas bd-II showed a broad activity maximum around pH 7. Likewise, the pH dependence of NO release from the reduced active site, an essential property of bd oxidases, differed between the two oxidases as detected by UV/vis spectroscopy. Both findings may be attributed to differences in the proton channel leading to the active site heme d. The channel comprises a titratable residue (Asp58B in bd-I and Glu58B in bd-II). Conservative mutations at this position drastically altered NO release demonstrating its contribution to the process.
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Affiliation(s)
- Iryna Makarchuk
- Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, Chimie de la Matière Complexe, Université de Strasbourg-CNRS, 67000 Strasbourg, France
| | - Jan Kägi
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr 21, 79104 Freiburg, Germany
| | - Tatjana Gerasimova
- Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, Chimie de la Matière Complexe, Université de Strasbourg-CNRS, 67000 Strasbourg, France; Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr 21, 79104 Freiburg, Germany
| | - Daniel Wohlwend
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr 21, 79104 Freiburg, Germany
| | - Thorsten Friedrich
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr 21, 79104 Freiburg, Germany
| | - Frédéric Melin
- Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, Chimie de la Matière Complexe, Université de Strasbourg-CNRS, 67000 Strasbourg, France
| | - Petra Hellwig
- Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, Chimie de la Matière Complexe, Université de Strasbourg-CNRS, 67000 Strasbourg, France.
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10
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Liang Y, Plourde A, Bueler SA, Liu J, Brzezinski P, Vahidi S, Rubinstein JL. Structure of mycobacterial respiratory complex I. Proc Natl Acad Sci U S A 2023; 120:e2214949120. [PMID: 36952383 PMCID: PMC10068793 DOI: 10.1073/pnas.2214949120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 02/10/2023] [Indexed: 03/24/2023] Open
Abstract
Oxidative phosphorylation, the combined activity of the electron transport chain (ETC) and adenosine triphosphate synthase, has emerged as a valuable target for the treatment of infection by Mycobacterium tuberculosis and other mycobacteria. The mycobacterial ETC is highly branched with multiple dehydrogenases transferring electrons to a membrane-bound pool of menaquinone and multiple oxidases transferring electrons from the pool. The proton-pumping type I nicotinamide adenine dinucleotide (NADH) dehydrogenase (Complex I) is found in low abundance in the plasma membranes of mycobacteria in typical in vitro culture conditions and is often considered dispensable. We found that growth of Mycobacterium smegmatis in carbon-limited conditions greatly increased the abundance of Complex I and allowed isolation of a rotenone-sensitive preparation of the enzyme. Determination of the structure of the complex by cryoEM revealed the "orphan" two-component response regulator protein MSMEG_2064 as a subunit of the assembly. MSMEG_2064 in the complex occupies a site similar to the proposed redox-sensing subunit NDUFA9 in eukaryotic Complex I. An apparent purine nucleoside triphosphate within the NuoG subunit resembles the GTP-derived molybdenum cofactor in homologous formate dehydrogenase enzymes. The membrane region of the complex binds acyl phosphatidylinositol dimannoside, a characteristic three-tailed lipid from the mycobacterial membrane. The structure also shows menaquinone, which is preferentially used over ubiquinone by gram-positive bacteria, in two different positions along the quinone channel, comparable to ubiquinone in other structures and suggesting a conserved quinone binding mechanism.
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Affiliation(s)
- Yingke Liang
- Molecular Medicine Program, The Hospital for Sick Children, TorontoM5G 0A4, Canada
- Department of Biochemistry, University of Toronto, TorontoM5S 1A8, Canada
| | - Alicia Plourde
- Department of Molecular and Cellular Biology, University of Guelph, TorontoN1G 2W1, Canada
| | - Stephanie A. Bueler
- Molecular Medicine Program, The Hospital for Sick Children, TorontoM5G 0A4, Canada
| | - Jun Liu
- Department of Molecular Genetics, University of Toronto, TorontoM5S 1A8, Canada
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91Stockholm, Sweden
| | - Siavash Vahidi
- Department of Molecular and Cellular Biology, University of Guelph, TorontoN1G 2W1, Canada
| | - John L. Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, TorontoM5G 0A4, Canada
- Department of Biochemistry, University of Toronto, TorontoM5S 1A8, Canada
- Department of Medical Biophysics, University of Toronto, TorontoM5G 1L7, Canada
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11
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Cao YC, Liao RZ. QM Calculations Revealed that Outer-Sphere Electron Transfer Boosted O-O Bond Cleavage in the Multiheme-Dependent Cytochrome bd Oxygen Reductase. Inorg Chem 2023; 62:4066-4075. [PMID: 36857027 DOI: 10.1021/acs.inorgchem.2c03742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
The cytochrome bd oxygen reductase catalyzes the four-electron reduction of dioxygen to two water molecules. The structure of this enzyme reveals three heme molecules in the active site, which differs from that of heme-copper cytochrome c oxidase. The quantum chemical cluster approach was used to uncover the reaction mechanism of this intriguing metalloenzyme. The calculations suggested that a proton-coupled electron transfer reduction occurs first to generate a ferrous heme b595. This is followed by the dioxygen binding at the heme d center coupled with an outer-sphere electron transfer from the ferrous heme b595 to the dioxygen moiety, affording a ferric ion superoxide intermediate. A second proton-coupled electron transfer produces a heme d ferric hydroperoxide, which undergoes efficient O-O bond cleavage facilitated by an outer-sphere electron transfer from the ferrous heme b595 to the O-O σ* orbital and an inner-sphere proton transfer from the heme d hydroxyl group to the leaving hydroxide. The synergistic benefits of the two types of hemes rationalize the highly efficient oxygen reduction repertoire for the multi-heme-dependent cytochrome bd oxygen reductase family.
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Affiliation(s)
- Yu-Chen Cao
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Rong-Zhen Liao
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
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12
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Jeffreys LN, Ardrey A, Hafiz TA, Dyer LA, Warman AJ, Mosallam N, Nixon GL, Fisher NE, Hong WD, Leung SC, Aljayyoussi G, Bibby J, Almeida DV, Converse PJ, Fotouhi N, Berry NG, Nuermberger EL, Upton AM, O'Neill PM, Ward SA, Biagini GA. Identification of 2-Aryl-Quinolone Inhibitors of Cytochrome bd and Chemical Validation of Combination Strategies for Respiratory Inhibitors against Mycobacterium tuberculosis. ACS Infect Dis 2023; 9:221-238. [PMID: 36606559 PMCID: PMC9926492 DOI: 10.1021/acsinfecdis.2c00283] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Mycobacterium tuberculosis cytochrome bd quinol oxidase (cyt bd), the alternative terminal oxidase of the respiratory chain, has been identified as playing a key role during chronic infection and presents a putative target for the development of novel antitubercular agents. Here, we report confirmation of successful heterologous expression of M. tuberculosis cytochrome bd. The heterologous M. tuberculosis cytochrome bd expression system was used to identify a chemical series of inhibitors based on the 2-aryl-quinolone pharmacophore. Cytochrome bd inhibitors displayed modest efficacy in M. tuberculosis growth suppression assays together with a bacteriostatic phenotype in time-kill curve assays. Significantly, however, inhibitor combinations containing our front-runner cyt bd inhibitor CK-2-63 with either cyt bcc-aa3 inhibitors (e.g., Q203) and/or adenosine triphosphate (ATP) synthase inhibitors (e.g., bedaquiline) displayed enhanced efficacy with respect to the reduction of mycobacterium oxygen consumption, growth suppression, and in vitro sterilization kinetics. In vivo combinations of Q203 and CK-2-63 resulted in a modest lowering of lung burden compared to treatment with Q203 alone. The reduced efficacy in the in vivo experiments compared to in vitro experiments was shown to be a result of high plasma protein binding and a low unbound drug exposure at the target site. While further development is required to improve the tractability of cyt bd inhibitors for clinical evaluation, these data support the approach of using small-molecule inhibitors to target multiple components of the branched respiratory chain of M. tuberculosis as a combination strategy to improve therapeutic and pharmacokinetic/pharmacodynamic (PK/PD) indices related to efficacy.
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Affiliation(s)
- Laura N Jeffreys
- Centre for Drugs and Diagnostics, Department of Tropical Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, U.K
| | - Alison Ardrey
- Centre for Drugs and Diagnostics, Department of Tropical Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, U.K
| | - Taghreed A Hafiz
- Centre for Drugs and Diagnostics, Department of Tropical Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, U.K
| | - Lauri-Anne Dyer
- Centre for Drugs and Diagnostics, Department of Tropical Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, U.K
| | - Ashley J Warman
- Centre for Drugs and Diagnostics, Department of Tropical Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, U.K
| | - Nada Mosallam
- Department of Chemistry, University of Liverpool, LiverpoolL69 7ZD, U.K
| | - Gemma L Nixon
- Department of Chemistry, University of Liverpool, LiverpoolL69 7ZD, U.K
| | - Nicholas E Fisher
- Centre for Drugs and Diagnostics, Department of Tropical Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, U.K
| | - W David Hong
- Department of Chemistry, University of Liverpool, LiverpoolL69 7ZD, U.K
| | - Suet C Leung
- Department of Chemistry, University of Liverpool, LiverpoolL69 7ZD, U.K
| | - Ghaith Aljayyoussi
- Centre for Drugs and Diagnostics, Department of Tropical Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, U.K
| | - Jaclyn Bibby
- Department of Chemistry, University of Liverpool, LiverpoolL69 7ZD, U.K
| | - Deepak V Almeida
- Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland21205, United States
| | - Paul J Converse
- Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland21205, United States
| | - Nader Fotouhi
- Global Alliance for TB Drug Development, New York, New York10005, United States
| | - Neil G Berry
- Department of Chemistry, University of Liverpool, LiverpoolL69 7ZD, U.K
| | - Eric L Nuermberger
- Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland21205, United States
| | - Anna M Upton
- Global Alliance for TB Drug Development, New York, New York10005, United States.,Evotec (US) Inc., 303B College Road East, Princeton, New Jersey08540, United States
| | - Paul M O'Neill
- Department of Chemistry, University of Liverpool, LiverpoolL69 7ZD, U.K
| | - Stephen A Ward
- Centre for Drugs and Diagnostics, Department of Tropical Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, U.K
| | - Giancarlo A Biagini
- Centre for Drugs and Diagnostics, Department of Tropical Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, U.K
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13
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Grund TN, Kabashima Y, Kusumoto T, Wu D, Welsch S, Sakamoto J, Michel H, Safarian S. The cryoEM structure of cytochrome bd from C. glutamicum provides novel insights into structural properties of actinobacterial terminal oxidases. Front Chem 2023; 10:1085463. [PMID: 36688035 PMCID: PMC9846854 DOI: 10.3389/fchem.2022.1085463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 12/12/2022] [Indexed: 01/05/2023] Open
Abstract
Cytochromes bd are essential for microaerobic respiration of many prokaryotes including a number of human pathogens. These enzymes catalyze the reduction of molecular oxygen to water using quinols as electron donors. Their importance for prokaryotic survival and the absence of eukaryotic homologs make these enzyme ideal targets for antimicrobial drugs. Here, we determined the cryoEM structure of the menaquinol-oxidizing cytochrome bd-type oxygen reductase of the facultative anaerobic Actinobacterium Corynebacterium glutamicum at a resolution of 2.7 Å. The obtained structure adopts the signature pseudosymmetrical heterodimeric architecture of canonical cytochrome bd oxidases formed by the core subunits CydA and CydB. No accessory subunits were identified for this cytochrome bd homolog. The two b-type hemes and the oxygen binding heme d are organized in a triangular geometry with a protein environment around these redox cofactors similar to that of the closely related cytochrome bd from M. tuberculosis. We identified oxygen and a proton conducting channels emerging from the membrane space and the cytoplasm, respectively. Compared to the prototypical enzyme homolog from the E. coli, the most apparent difference is found in the location and size of the proton channel entry site. In canonical cytochrome bd oxidases quinol oxidation occurs at the highly flexible periplasmic Q-loop located in the loop region between TMHs six and seven. An alternative quinol-binding site near heme b 595 was previously identified for cytochrome bd from M. tuberculosis. We discuss the relevance of the two quinol oxidation sites in actinobacterial bd-type oxidases and highlight important differences that may explain functional and electrochemical differences between C. glutamicum and M. tuberculosis. This study expands our current understanding of the structural diversity of actinobacterial and proteobacterial cytochrome bd oxygen reductases and provides deeper insights into the unique structural and functional properties of various cytochrome bd variants from different phylae.
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Affiliation(s)
- Tamara N. Grund
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Yoshiki Kabashima
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Fukuoka, Japan
| | - Tomoichirou Kusumoto
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Fukuoka, Japan
| | - Di Wu
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Sonja Welsch
- Central Electron Microscopy Facility, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Junshi Sakamoto
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Fukuoka, Japan
| | - Hartmut Michel
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Schara Safarian
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany,Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand,Fraunhofer Institute for Translational Medicine and Pharmacology ITMP Frankfurt, Frankfurt, Germany,*Correspondence: Schara Safarian,
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14
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Response of Mycobacterium smegmatis to the Cytochrome bcc Inhibitor Q203. Int J Mol Sci 2022; 23:ijms231810331. [PMID: 36142240 PMCID: PMC9498996 DOI: 10.3390/ijms231810331] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 11/16/2022] Open
Abstract
For the design of next-generation tuberculosis chemotherapy, insight into bacterial defence against drugs is required. Currently, targeting respiration has attracted strong attention for combatting drug-resistant mycobacteria. Q203 (telacebec), an inhibitor of the cytochrome bcc complex in the mycobacterial respiratory chain, is currently evaluated in phase-2 clinical trials. Q203 has bacteriostatic activity against M. tuberculosis, which can be converted to bactericidal activity by concurrently inhibiting an alternative branch of the mycobacterial respiratory chain, cytochrome bd. In contrast, non-tuberculous mycobacteria, such as Mycobacterium smegmatis, show only very little sensitivity to Q203. In this report, we investigated factors that M. smegmatis employs to adapt to Q203 in the presence or absence of a functional cytochrome bd, especially regarding its terminal oxidases. In the presence of a functional cytochrome bd, M. smegmatis responds to Q203 by increasing the expression of cytochrome bcc as well as of cytochrome bd, whereas a M. smegmatisbd-KO strain adapted to Q203 by increasing the expression of cytochrome bcc. Interestingly, single-cell studies revealed cell-to-cell variability in drug adaptation. We also investigated the role of a putative second cytochrome bd isoform postulated for M. smegmatis. Although this putative isoform showed differential expression in response to Q203 in the M. smegmatisbd-KO strain, it did not display functional features similar to the characterised cytochrome bd variant.
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15
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McNeil MB, Cheung CY, Waller NJE, Adolph C, Chapman CL, Seeto NEJ, Jowsey W, Li Z, Hameed HMA, Zhang T, Cook GM. Uncovering interactions between mycobacterial respiratory complexes to target drug-resistant Mycobacterium tuberculosis. Front Cell Infect Microbiol 2022; 12:980844. [PMID: 36093195 PMCID: PMC9461714 DOI: 10.3389/fcimb.2022.980844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/03/2022] [Indexed: 11/24/2022] Open
Abstract
Mycobacterium tuberculosis remains a leading cause of infectious disease morbidity and mortality for which new drug combination therapies are needed. Mycobacterial bioenergetics has emerged as a promising space for the development of novel therapeutics. Further to this, unique combinations of respiratory inhibitors have been shown to have synergistic or synthetic lethal interactions, suggesting that combinations of bioenergetic inhibitors could drastically shorten treatment times. Realizing the full potential of this unique target space requires an understanding of which combinations of respiratory complexes, when inhibited, have the strongest interactions and potential in a clinical setting. In this review, we discuss (i) chemical-interaction, (ii) genetic-interaction and (iii) chemical-genetic interaction studies to explore the consequences of inhibiting multiple mycobacterial respiratory components. We provide potential mechanisms to describe the basis for the strongest interactions. Finally, whilst we place an emphasis on interactions that occur with existing bioenergetic inhibitors, by highlighting interactions that occur with alternative respiratory components we envision that this information will provide a rational to further explore alternative proteins as potential drug targets and as part of unique drug combinations.
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Affiliation(s)
- Matthew B. McNeil
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Maurice Wilkins, Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
- *Correspondence: Matthew B. McNeil, ; Gregory M. Cook,
| | - Chen-Yi Cheung
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Natalie J. E. Waller
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Cara Adolph
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Cassandra L. Chapman
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Noon E. J. Seeto
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - William Jowsey
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Zhengqiu Li
- School of Pharmacy, Jinan University, Guangzhou, China
| | - H. M. Adnan Hameed
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health (GIBH), Chinese Academy of Sciences (CAS), Guangzhou, China
- China-New Zealand Joint Laboratory of Biomedicine and Health, Guangzhou Institutes of Biomedicine and Health (GIBH), Chinese Academy of Sciences (CAS), Guangzhou, China
- Guangdong-Hong Kong-Macau Joint Laboratory of Respiratory Infectious Diseases, Guangzhou, China
- University of Chinese Academy of Sciences (UCAS), Beijing, China
| | - Tianyu Zhang
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health (GIBH), Chinese Academy of Sciences (CAS), Guangzhou, China
- China-New Zealand Joint Laboratory of Biomedicine and Health, Guangzhou Institutes of Biomedicine and Health (GIBH), Chinese Academy of Sciences (CAS), Guangzhou, China
- Guangdong-Hong Kong-Macau Joint Laboratory of Respiratory Infectious Diseases, Guangzhou, China
- University of Chinese Academy of Sciences (UCAS), Beijing, China
| | - Gregory M. Cook
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Maurice Wilkins, Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
- *Correspondence: Matthew B. McNeil, ; Gregory M. Cook,
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16
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Forte E, Nastasi MR, Borisov VB. Preparations of Terminal Oxidase Cytochrome bd-II Isolated from Escherichia coli Reveal Significant Hydrogen Peroxide Scavenging Activity. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:720-730. [PMID: 36171653 DOI: 10.1134/s0006297922080041] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 06/16/2023]
Abstract
Cytochrome bd-II is one of the three terminal quinol oxidases of the aerobic respiratory chain of Escherichia coli. Preparations of the detergent-solubilized untagged bd-II oxidase isolated from the bacterium were shown to scavenge hydrogen peroxide (H2O2) with high rate producing molecular oxygen (O2). Addition of H2O2 to the same buffer that does not contain enzyme or contains thermally denatured cytochrome bd-II does not lead to any O2 production. The latter observation rules out involvement of adventitious transition metals bound to the protein. The H2O2-induced O2 production is not susceptible to inhibition by N-ethylmaleimide (the sulfhydryl binding compound), antimycin A (the compound that binds specifically to a quinol binding site), and CO (diatomic gas that binds specifically to the reduced heme d). However, O2 formation is inhibited by cyanide (IC50 = 4.5 ± 0.5 µM) and azide. Addition of H2O2 in the presence of dithiothreitol and ubiquinone-1 does not inactivate cytochrome bd-II and apparently does not affect the O2 reductase activity of the enzyme. The ability of cytochrome bd-II to detoxify H2O2 could play a role in bacterial physiology by conferring resistance to the peroxide-mediated stress.
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Affiliation(s)
- Elena Forte
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, I-00185, Italy
| | - Martina R Nastasi
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, I-00185, Italy
| | - Vitaliy B Borisov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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17
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Bioenergetics and Reactive Nitrogen Species in Bacteria. Int J Mol Sci 2022; 23:ijms23137321. [PMID: 35806323 PMCID: PMC9266656 DOI: 10.3390/ijms23137321] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 11/24/2022] Open
Abstract
The production of reactive nitrogen species (RNS) by the innate immune system is part of the host’s defense against invading pathogenic bacteria. In this review, we summarize recent studies on the molecular basis of the effects of nitric oxide and peroxynitrite on microbial respiration and energy conservation. We discuss possible molecular mechanisms underlying RNS resistance in bacteria mediated by unique respiratory oxygen reductases, the mycobacterial bcc-aa3 supercomplex, and bd-type cytochromes. A complete picture of the impact of RNS on microbial bioenergetics is not yet available. However, this research area is developing very rapidly, and the knowledge gained should help us develop new methods of treating infectious diseases.
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18
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Anand P, Akhter Y. A review on enzyme complexes of electron transport chain from Mycobacterium tuberculosis as promising drug targets. Int J Biol Macromol 2022; 212:474-494. [PMID: 35613677 DOI: 10.1016/j.ijbiomac.2022.05.124] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/05/2022] [Accepted: 05/17/2022] [Indexed: 12/20/2022]
Abstract
Energy metabolism is a universal process occurring in all life forms. In Mycobacterium tuberculosis (Mtb), energy production is carried out in two possible ways, oxidative phosphorylation (OxPhos) and substrate-level phosphorylation. Mtb is an obligate aerobic bacterium, making it dependent on OxPhos for ATP synthesis and growth. Mtb inhabits varied micro-niches during the infection cycle, outside and within the host cells, which alters its primary metabolic pathways during the pathogenesis. In this review, we discuss cellular respiration in the context of the mechanism and structural importance of the proteins and enzyme complexes involved. These protein-protein complexes have been proven to be essential for Mtb virulence as they aid the bacteria's survival during aerobic and hypoxic conditions. ATP synthase, a crucial component of the electron transport chain, has been in the limelight, as a prominent drug target against tuberculosis. Likewise, in this review, we have explored other protein-protein complexes of the OxPhos pathway, their functional essentiality, and their mechanism in Mtb's diverse lifecycle. The review summarises crucial target proteins and reported inhibitors of the electron transport chain pathway of Mtb.
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Affiliation(s)
- Pragya Anand
- Department of Biotechnology, School of Life Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Lucknow, Uttar Pradesh 226025, India
| | - Yusuf Akhter
- Department of Biotechnology, School of Life Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Lucknow, Uttar Pradesh 226025, India.
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19
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Friedrich T, Wohlwend D, Borisov VB. Recent Advances in Structural Studies of Cytochrome bd and Its Potential Application as a Drug Target. Int J Mol Sci 2022; 23:ijms23063166. [PMID: 35328590 PMCID: PMC8951039 DOI: 10.3390/ijms23063166] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/14/2022] [Accepted: 03/14/2022] [Indexed: 02/06/2023] Open
Abstract
Cytochrome bd is a triheme copper-free terminal oxidase in membrane respiratory chains of prokaryotes. This unique molecular machine couples electron transfer from quinol to O2 with the generation of a proton motive force without proton pumping. Apart from energy conservation, the bd enzyme plays an additional key role in the microbial cell, being involved in the response to different environmental stressors. Cytochrome bd promotes virulence in a number of pathogenic species that makes it a suitable molecular drug target candidate. This review focuses on recent advances in understanding the structure of cytochrome bd and the development of its selective inhibitors.
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Affiliation(s)
- Thorsten Friedrich
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany; (T.F.); (D.W.)
| | - Daniel Wohlwend
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany; (T.F.); (D.W.)
| | - Vitaliy B. Borisov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow, Russia
- Correspondence:
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20
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Structure of Escherichia coli cytochrome bd-II type oxidase with bound aurachin D. Nat Commun 2021; 12:6498. [PMID: 34764272 PMCID: PMC8585947 DOI: 10.1038/s41467-021-26835-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
Cytochrome bd quinol:O2 oxidoreductases are respiratory terminal oxidases so far only identified in prokaryotes, including several pathogenic bacteria. Escherichia coli contains two bd oxidases of which only the bd-I type is structurally characterized. Here, we report the structure of the Escherichia coli cytochrome bd-II type oxidase with the bound inhibitor aurachin D as obtained by electron cryo-microscopy at 3 Å resolution. The oxidase consists of subunits AppB, C and X that show an architecture similar to that of bd-I. The three heme cofactors are found in AppC, while AppB is stabilized by a structural ubiquinone-8 at the homologous positions. A fourth subunit present in bd-I is lacking in bd-II. Accordingly, heme b595 is exposed to the membrane but heme d embedded within the protein and showing an unexpectedly high redox potential is the catalytically active centre. The structure of the Q-loop is fully resolved, revealing the specific aurachin binding. Terminal bd oxidases endow bacterial pathogens with resistance to cellular stressors. The authors report the structure of E. coli bd-II type oxidase with the bound inhibitor aurachin D, providing a structural basis for the design of specifically binding antibiotics.
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21
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Siletsky SA, Borisov VB. Proton Pumping and Non-Pumping Terminal Respiratory Oxidases: Active Sites Intermediates of These Molecular Machines and Their Derivatives. Int J Mol Sci 2021; 22:10852. [PMID: 34639193 PMCID: PMC8509429 DOI: 10.3390/ijms221910852] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/04/2021] [Accepted: 10/05/2021] [Indexed: 11/16/2022] Open
Abstract
Terminal respiratory oxidases are highly efficient molecular machines. These most important bioenergetic membrane enzymes transform the energy of chemical bonds released during the transfer of electrons along the respiratory chains of eukaryotes and prokaryotes from cytochromes or quinols to molecular oxygen into a transmembrane proton gradient. They participate in regulatory cascades and physiological anti-stress reactions in multicellular organisms. They also allow microorganisms to adapt to low-oxygen conditions, survive in chemically aggressive environments and acquire antibiotic resistance. To date, three-dimensional structures with atomic resolution of members of all major groups of terminal respiratory oxidases, heme-copper oxidases, and bd-type cytochromes, have been obtained. These groups of enzymes have different origins and a wide range of functional significance in cells. At the same time, all of them are united by a catalytic reaction of four-electron reduction in oxygen into water which proceeds without the formation and release of potentially dangerous ROS from active sites. The review analyzes recent structural and functional studies of oxygen reduction intermediates in the active sites of terminal respiratory oxidases, the features of catalytic cycles, and the properties of the active sites of these enzymes.
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Affiliation(s)
- Sergey A. Siletsky
- Department of Bioenergetics, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - Vitaliy B. Borisov
- Department of Molecular Energetics of Microorganisms, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia;
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