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Singh PK, Sharma P, Afanzar O, Goldfarb MH, Maklashina E, Eisenbach M, Cecchini G, Iverson TM. CryoEM structures reveal how the bacterial flagellum rotates and switches direction. Nat Microbiol 2024; 9:1271-1281. [PMID: 38632342 PMCID: PMC11087270 DOI: 10.1038/s41564-024-01674-1] [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: 08/19/2023] [Accepted: 03/12/2024] [Indexed: 04/19/2024]
Abstract
Bacterial chemotaxis requires bidirectional flagellar rotation at different rates. Rotation is driven by a flagellar motor, which is a supercomplex containing multiple rings. Architectural uncertainty regarding the cytoplasmic C-ring, or 'switch', limits our understanding of how the motor transmits torque and direction to the flagellar rod. Here we report cryogenic electron microscopy structures for Salmonella enterica serovar typhimurium inner membrane MS-ring and C-ring in a counterclockwise pose (4.0 Å) and isolated C-ring in a clockwise pose alone (4.6 Å) and bound to a regulator (5.9 Å). Conformational differences between rotational poses include a 180° shift in FliF/FliG domains that rotates the outward-facing MotA/B binding site to inward facing. The regulator has specificity for the clockwise pose by bridging elements unique to this conformation. We used these structures to propose how the switch reverses rotation and transmits torque to the flagellum, which advances the understanding of bacterial chemotaxis and bidirectional motor rotation.
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Affiliation(s)
- Prashant K Singh
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Pankaj Sharma
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Oshri Afanzar
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Margo H Goldfarb
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Elena Maklashina
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, CA, USA
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
| | - Michael Eisenbach
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Gary Cecchini
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, CA, USA
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
| | - T M Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA.
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA.
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA.
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA.
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2
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Bhandari V, Reichheld SE, Houliston S, Lemak A, Arrowsmith CH, Sharpe S, Houry WA. The RavA-ViaA chaperone complex modulates bacterial persistence through its association with the fumarate reductase enzyme. J Biol Chem 2023; 299:105199. [PMID: 37660904 PMCID: PMC10585395 DOI: 10.1016/j.jbc.2023.105199] [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: 06/28/2023] [Revised: 08/24/2023] [Accepted: 08/28/2023] [Indexed: 09/05/2023] Open
Abstract
Regulatory ATPase variant A (RavA) is a MoxR AAA+ protein that functions together with a partner protein termed von Willebrand factor type A interacting with AAA+ ATPase (ViaA). RavA-ViaA are functionally associated with anaerobic respiration in Escherichia coli through interactions with the fumarate reductase (Frd) electron transport complex. Through this association, RavA and ViaA modulate the activity of the Frd complex and, hence, are proposed to have chaperone-like activity. However, the functional role of RavA-ViaA in the cell is not yet well established. We had demonstrated that RavA-ViaA can sensitize E. coli cells to sublethal concentrations of the aminoglycoside class of antibiotics. Since Frd has been associated with bacterial persistence against antibiotics, the relationship of RavA-ViaA and Frd was explored within this context. Experiments performed here reveal a function of RavA-ViaA in bacterial persistence upon treatment with antibiotics through the association of the chaperone complex with Frd. As part of this work, the NMR structure of the N-terminal domain of ViaA was solved. The structure reveals a novel alpha helical fold, which we name the VAN fold, that has not been observed before. We show that this domain is required for the function of the chaperone complex. We propose that modulating the levels of RavA-ViaA could enhance the susceptibility of Gram-negative bacteria to antibiotics.
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Affiliation(s)
- Vaibhav Bhandari
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Sean E Reichheld
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Scott Houliston
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Alexander Lemak
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Cheryl H Arrowsmith
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; Structural Genomics Consortium, Toronto, Ontario, Canada
| | - Simon Sharpe
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Walid A Houry
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Chemistry, University of Toronto, Toronto, Ontario, Canada.
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3
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Oliveira RNS, de Aguiar SRMM, Pauleta SR. Coordination of the N-Terminal Heme in the Non-Classical Peroxidase from Escherichia coli. Molecules 2023; 28:4598. [PMID: 37375153 DOI: 10.3390/molecules28124598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 05/28/2023] [Accepted: 06/05/2023] [Indexed: 06/29/2023] Open
Abstract
The non-classical bacterial peroxidase from Escherichia coli, YhjA, is proposed to deal with peroxidative stress in the periplasm when the bacterium is exposed to anoxic environments, defending it from hydrogen peroxide and allowing it to thrive under those conditions. This enzyme has a predicted transmembrane helix and is proposed to receive electrons from the quinol pool in an electron transfer pathway involving two hemes (NT and E) to accomplish the reduction of hydrogen peroxide in the periplasm at the third heme (P). Compared with classical bacterial peroxidases, these enzymes have an additional N-terminal domain binding the NT heme. In the absence of a structure of this protein, several residues (M82, M125 and H134) were mutated to identify the axial ligand of the NT heme. Spectroscopic data demonstrate differences only between the YhjA and YhjA M125A variant. In the YhjA M125A variant, the NT heme is high-spin with a lower reduction potential than in the wild-type. Thermostability was studied by circular dichroism, demonstrating that YhjA M125A is thermodynamically more unstable than YhjA, with a lower TM (43 °C vs. 50 °C). These data also corroborate the structural model of this enzyme. The axial ligand of the NT heme was validated to be M125, and mutation of this residue was proven to affect the spectroscopic, kinetic, and thermodynamic properties of YhjA.
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Affiliation(s)
- Ricardo N S Oliveira
- Microbial Stress Lab, UCIBIO-Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Sara R M M de Aguiar
- Microbial Stress Lab, UCIBIO-Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Sofia R Pauleta
- Microbial Stress Lab, UCIBIO-Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
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4
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Iverson TM, Singh PK, Cecchini G. An evolving view of complex II-noncanonical complexes, megacomplexes, respiration, signaling, and beyond. J Biol Chem 2023; 299:104761. [PMID: 37119852 PMCID: PMC10238741 DOI: 10.1016/j.jbc.2023.104761] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/20/2023] [Accepted: 04/22/2023] [Indexed: 05/01/2023] Open
Abstract
Mitochondrial complex II is traditionally studied for its participation in two key respiratory processes: the electron transport chain and the Krebs cycle. There is now a rich body of literature explaining how complex II contributes to respiration. However, more recent research shows that not all of the pathologies associated with altered complex II activity clearly correlate with this respiratory role. Complex II activity has now been shown to be necessary for a range of biological processes peripherally related to respiration, including metabolic control, inflammation, and cell fate. Integration of findings from multiple types of studies suggests that complex II both participates in respiration and controls multiple succinate-dependent signal transduction pathways. Thus, the emerging view is that the true biological function of complex II is well beyond respiration. This review uses a semichronological approach to highlight major paradigm shifts that occurred over time. Special emphasis is given to the more recently identified functions of complex II and its subunits because these findings have infused new directions into an established field.
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Affiliation(s)
- T M Iverson
- Departments of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Departments of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA.
| | - Prashant K Singh
- Departments of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Gary Cecchini
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, California, USA; Department of Biochemistry & Biophysics, University of California, San Francisco, California, USA.
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5
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Han F, Hu Y, Wu M, He Z, Tian H, Zhou L. Structures of Tetrahymena thermophila respiratory megacomplexes on the tubular mitochondrial cristae. Nat Commun 2023; 14:2542. [PMID: 37248254 DOI: 10.1038/s41467-023-38158-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 04/19/2023] [Indexed: 05/31/2023] Open
Abstract
Tetrahymena thermophila, a classic ciliate model organism, has been shown to possess tubular mitochondrial cristae and highly divergent electron transport chain involving four transmembrane protein complexes (I-IV). Here we report cryo-EM structures of its ~8 MDa megacomplex IV2 + (I + III2 + II)2, as well as a ~ 10.6 MDa megacomplex (IV2 + I + III2 + II)2 at lower resolution. In megacomplex IV2 + (I + III2 + II)2, each CIV2 protomer associates one copy of supercomplex I + III2 and one copy of CII, forming a half ring-shaped architecture that adapts to the membrane curvature of mitochondrial cristae. Megacomplex (IV2 + I + III2 + II)2 defines the relative position between neighbouring half rings and maintains the proximity between CIV2 and CIII2 cytochrome c binding sites. Our findings expand the current understanding of divergence in eukaryotic electron transport chain organization and how it is related to mitochondrial morphology.
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Affiliation(s)
- Fangzhu Han
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
| | - Yiqi Hu
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
| | - Mengchen Wu
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
| | - Zhaoxiang He
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
| | - Hongtao Tian
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
| | - Long Zhou
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China.
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China.
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6
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Du Z, Zhou X, Lai Y, Xu J, Zhang Y, Zhou S, Feng Z, Yu L, Tang Y, Wang W, Yu L, Tian C, Ran T, Chen H, Guddat LW, Liu F, Gao Y, Rao Z, Gong H. Structure of the human respiratory complex II. Proc Natl Acad Sci U S A 2023; 120:e2216713120. [PMID: 37098072 PMCID: PMC10161127 DOI: 10.1073/pnas.2216713120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 03/10/2023] [Indexed: 04/26/2023] Open
Abstract
Human complex II is a key protein complex that links two essential energy-producing processes: the tricarboxylic acid cycle and oxidative phosphorylation. Deficiencies due to mutagenesis have been shown to cause mitochondrial disease and some types of cancers. However, the structure of this complex is yet to be resolved, hindering a comprehensive understanding of the functional aspects of this molecular machine. Here, we have determined the structure of human complex II in the presence of ubiquinone at 2.86 Å resolution by cryoelectron microscopy, showing it comprises two water-soluble subunits, SDHA and SDHB, and two membrane-spanning subunits, SDHC and SDHD. This structure allows us to propose a route for electron transfer. In addition, clinically relevant mutations are mapped onto the structure. This mapping provides a molecular understanding to explain why these variants have the potential to produce disease.
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Affiliation(s)
- Zhanqiang Du
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Xiaoting Zhou
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China
| | - Yuezheng Lai
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Jinxu Xu
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Yuying Zhang
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Shan Zhou
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Ziyan Feng
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Long Yu
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Yanting Tang
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Weiwei Wang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Lu Yu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Changlin Tian
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Ting Ran
- Innovative Center For Pathogen Research, Guangzhou Laboratory, Guangzhou 510005, China
| | - Hongming Chen
- Innovative Center For Pathogen Research, Guangzhou Laboratory, Guangzhou 510005, China
| | - Luke W Guddat
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Fengjiang Liu
- Innovative Center For Pathogen Research, Guangzhou Laboratory, Guangzhou 510005, China
| | - Yan Gao
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Zihe Rao
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- Laboratory of Structural Biology, Tsinghua University, Beijing 100084, China
| | - Hongri Gong
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
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7
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Unusual reactivity of a flavin in a bifurcating electron-transferring flavoprotein leads to flavin modification and a charge-transfer complex. J Biol Chem 2022; 298:102606. [PMID: 36257407 PMCID: PMC9713284 DOI: 10.1016/j.jbc.2022.102606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 10/08/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022] Open
Abstract
From the outset, canonical electron transferring flavoproteins (ETFs) earned a reputation for containing modified flavin. We now show that modification occurs in the recently recognized bifurcating (Bf) ETFs as well. In Bf ETFs, the 'electron transfer' (ET) flavin mediates single electron transfer via a stable anionic semiquinone state, akin to the FAD of canonical ETFs, whereas a second flavin mediates bifurcation (the Bf FAD). We demonstrate that the ET FAD undergoes transformation to two different modified flavins by a sequence of protein-catalyzed reactions that occurs specifically in the ET site, when the enzyme is maintained at pH 9 in an amine-based buffer. Our optical and mass spectrometric characterizations identify 8-formyl flavin early in the process and 8-amino flavins (8AFs) at later times. The latter have not previously been documented in an ETF to our knowledge. Mass spectrometry of flavin products formed in Tris or bis-tris-aminopropane solutions demonstrates that the source of the amine adduct is the buffer. Stepwise reduction of the 8AF demonstrates that it can explain a charge transfer band observed near 726 nm in Bf ETF, as a complex involving the hydroquinone state of the 8AF in the ET site with the oxidized state of unmodified flavin in the Bf site. This supports the possibility that Bf ETF can populate a conformation enabling direct electron transfer between its two flavins, as has been proposed for cofactors brought together in complexes between ETF and its partner proteins.
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Komatsuya K, Sakura T, Shiomi K, Ōmura S, Hikosaka K, Nozaki T, Kita K, Inaoka DK. Siccanin Is a Dual-Target Inhibitor of Plasmodium falciparum Mitochondrial Complex II and Complex III. Pharmaceuticals (Basel) 2022; 15:ph15070903. [PMID: 35890202 PMCID: PMC9319939 DOI: 10.3390/ph15070903] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 02/05/2023] Open
Abstract
Plasmodium falciparum contains several mitochondrial electron transport chain (ETC) dehydrogenases shuttling electrons from the respective substrates to the ubiquinone pool, from which electrons are consecutively transferred to complex III, complex IV, and finally to the molecular oxygen. The antimalarial drug atovaquone inhibits complex III and validates this parasite’s ETC as an attractive target for chemotherapy. Among the ETC dehydrogenases from P. falciparum, dihydroorotate dehydrogenase, an essential enzyme used in de novo pyrimidine biosynthesis, and complex III are the two enzymes that have been characterized and validated as drug targets in the blood-stage parasite, while complex II has been shown to be essential for parasite survival in the mosquito stage; therefore, these enzymes and complex II are considered candidate drug targets for blocking parasite transmission. In this study, we identified siccanin as the first (to our knowledge) nanomolar inhibitor of the P. falciparum complex II. Moreover, we demonstrated that siccanin also inhibits complex III in the low-micromolar range. Siccanin did not inhibit the corresponding complexes from mammalian mitochondria even at high concentrations. Siccanin inhibited the growth of P. falciparum with IC50 of 8.4 μM. However, the growth inhibition of the P. falciparum blood stage did not correlate with ETC inhibition, as demonstrated by lack of resistance to siccanin in the yDHODH-3D7 (EC50 = 10.26 μM) and Dd2-ELQ300 strains (EC50 = 18.70 μM), suggesting a third mechanism of action that is unrelated to mitochondrial ETC inhibition. Hence, siccanin has at least a dual mechanism of action, being the first potent and selective inhibitor of P. falciparum complexes II and III over mammalian enzymes and so is a potential candidate for the development of a new class of antimalarial drugs.
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Affiliation(s)
- Keisuke Komatsuya
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; (K.K.); (T.N.)
- Laboratory of Biomembrane, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Takaya Sakura
- Department of Molecular Infection Dynamics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki 852-8523, Japan;
- School of Tropical Medicine and Global Health, Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
| | - Kazuro Shiomi
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo 108-8641, Japan;
| | - Satoshi Ōmura
- Ōmura Satoshi Memorial Institute, Kitasato University, Minato-ku, Tokyo 108-8641, Japan;
| | - Kenji Hikosaka
- Department of Infection and Host Defense, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan;
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; (K.K.); (T.N.)
| | - Kiyoshi Kita
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; (K.K.); (T.N.)
- School of Tropical Medicine and Global Health, Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
- Department of Host-Defense Biochemistry, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki 852-8523, Japan
- Correspondence: (K.K.); (D.K.I.); Tel.: +81-95-819-7575 (K.K.); +81-95-819-7230 (D.K.I.)
| | - Daniel Ken Inaoka
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; (K.K.); (T.N.)
- Department of Molecular Infection Dynamics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki 852-8523, Japan;
- School of Tropical Medicine and Global Health, Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
- Correspondence: (K.K.); (D.K.I.); Tel.: +81-95-819-7575 (K.K.); +81-95-819-7230 (D.K.I.)
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9
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Schwarz MGA, Antunes D, Corrêa PR, da Silva-Gonçalves AJ, Malaga W, Caffarena ER, Guilhot C, Mendonça-Lima L. Mycobacterium tuberculosis and M. bovis BCG Moreau Fumarate Reductase Operons Produce Different Polypeptides That May Be Related to Non-canonical Functions. Front Microbiol 2021; 11:624121. [PMID: 33510737 PMCID: PMC7835394 DOI: 10.3389/fmicb.2020.624121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/17/2020] [Indexed: 12/14/2022] Open
Abstract
Tuberculosis is a world widespread disease, caused by Mycobacterium tuberculosis (M.tb). Although considered an obligate aerobe, this organism can resist life-limiting conditions such as microaerophily mainly due to its set of enzymes responsible for energy production and coenzyme restoration under these conditions. One of these enzymes is fumarate reductase, an heterotetrameric complex composed of a catalytic (FrdA), an iron-sulfur cluster (FrdB) and two transmembrane (FrdC and FrdD) subunits involved in anaerobic respiration and important for the maintenance of membrane potential. In this work, aiming to further characterize this enzyme function in mycobacteria, we analyzed the expression of FrdB-containing proteins in M.tb and Mycobacterium bovis Bacillus Calmette–Guérin (BCG) Moreau, the Brazilian vaccine strain against tuberculosis. We identified three isoforms in both mycobacteria, two of them corresponding to the predicted encoded polypeptides of M.tb (27 kDa) and BCG Moreau (40 kDa) frd sequences, as due to an insertion on the latter’s operon a fused FrdBC protein is expected. The third 52 kDa band can be explained by a transcriptional slippage event, typically occurring when mutation arises in a repetitive region within a coding sequence, thought to reduce its impact allowing the production of both native and variant forms. Comparative modeling of the M.tb and BCG Moreau predicted protein complexes allowed the detection of subtle overall differences, showing a high degree of structure and maybe functional resemblance among them. Axenic growth and macrophage infection assays show that the frd locus is important for proper bacterial development in both scenarios, and that both M.tb’s and BCG Moreau’s alleles can partially revert the hampered phenotype of the knockout strain. Altogether, our results show that the frdABCD operon of Mycobacteria may have evolved to possess other yet non-described functions, such as those necessary during aerobic logarithmic growth and early stage steps of infection.
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Affiliation(s)
| | - Deborah Antunes
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | - Paloma Rezende Corrêa
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | | | - Wladimir Malaga
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, Université Paul Sabatier, Toulouse, France
| | - Ernesto Raul Caffarena
- Grupo de Biofísica Computacional e Modelagem Molecular, Programa de Computação Científica, Fiocruz, Rio de Janeiro, Brazil
| | - Christophe Guilhot
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, Université Paul Sabatier, Toulouse, France
| | - Leila Mendonça-Lima
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
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10
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Yoshida H, Kojima K, Shiota M, Yoshimatsu K, Yamazaki T, Ferri S, Tsugawa W, Kamitori S, Sode K. X-ray structure of the direct electron transfer-type FAD glucose dehydrogenase catalytic subunit complexed with a hitchhiker protein. Acta Crystallogr D Struct Biol 2019; 75:841-851. [PMID: 31478907 PMCID: PMC6719666 DOI: 10.1107/s2059798319010878] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 08/02/2019] [Indexed: 11/13/2022] Open
Abstract
The bacterial flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase complex derived from Burkholderia cepacia (BcGDH) is a representative molecule of direct electron transfer-type FAD-dependent dehydrogenase complexes. In this study, the X-ray structure of BcGDHγα, the catalytic subunit (α-subunit) of BcGDH complexed with a hitchhiker protein (γ-subunit), was determined. The most prominent feature of this enzyme is the presence of the 3Fe-4S cluster, which is located at the surface of the catalytic subunit and functions in intramolecular and intermolecular electron transfer from FAD to the electron-transfer subunit. The structure of the complex revealed that these two molecules are connected through disulfide bonds and hydrophobic interactions, and that the formation of disulfide bonds is required to stabilize the catalytic subunit. The structure of the complex revealed the putative position of the electron-transfer subunit. A comparison of the structures of BcGDHγα and membrane-bound fumarate reductases suggested that the whole BcGDH complex, which also includes the membrane-bound β-subunit containing three heme c moieties, may form a similar overall structure to fumarate reductases, thus accomplishing effective electron transfer.
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Affiliation(s)
- Hiromi Yoshida
- Life Science Research Center and Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan
| | - Katsuhiro Kojima
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Masaki Shiota
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Keiichi Yoshimatsu
- Department of Chemistry, Missouri State University, Springfield, MO 65897, USA
| | - Tomohiko Yamazaki
- Research Center for Functional Materials, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Stefano Ferri
- Department of Applied Chemistry and Biochemical Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8561, Japan
| | - Wakako Tsugawa
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Shigehiro Kamitori
- Life Science Research Center and Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan
| | - Koji Sode
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC 27599, USA
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11
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Koganitsky A, Tworowski D, Dadosh T, Cecchini G, Eisenbach M. A Mechanism of Modulating the Direction of Flagellar Rotation in Bacteria by Fumarate and Fumarate Reductase. J Mol Biol 2019; 431:3662-3676. [PMID: 31412261 DOI: 10.1016/j.jmb.2019.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 02/04/2023]
Abstract
Fumarate, an electron acceptor in anaerobic respiration of Escherichia coli, has an additional function of assisting the flagellar motor to shift from counterclockwise to clockwise rotation, with a consequent modulation of the bacterial swimming behavior. Fumarate transmits its effect to the motor via the fumarate reductase complex (FrdABCD), shown to bind to FliG-one of the motor's switch proteins. How binding of the FrdABCD respiratory enzyme to FliG enhances clockwise rotation and how fumarate is involved in this activity have remained puzzling. Here we show that the FrdA subunit in the presence of fumarate is sufficient for binding to FliG and for clockwise enhancement. We further demonstrate by in vitro binding assays and super-resolution microscopy in vivo that the mechanism by which fumarate-occupied FrdA enhances clockwise rotation involves its preferential binding to the clockwise state of FliG (FliGcw). Continuum electrostatics combined with docking analysis and conformational sampling endorsed the experimental conclusions and suggested that the FrdA-FliGcw interaction is driven by the positive electrostatic potential generated by FrdA and the negatively charged areas of FliG. They further demonstrated that fumarate changes FrdA's conformation to one that can bind to FliGcw. These findings also show that the reason for the failure of the succinate dehydrogenase flavoprotein SdhA (an almost-identical analog of FrdA shown to bind to FliG equally well) to enhance clockwise rotation is that it has no binding preference for FliGcw. We suggest that this mechanism is physiologically important as it can modulate the magnitude of ΔG0 between the clockwise and counterclockwise states of the motor to tune the motor to the growth conditions of the bacteria.
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Affiliation(s)
- Anna Koganitsky
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Dmitry Tworowski
- Department of Structural Biology, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Tali Dadosh
- Department of Chemical Research Support, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Gary Cecchini
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, CA 94121, USA; Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, USA
| | - Michael Eisenbach
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 7610001 Rehovot, Israel.
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12
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Lubek D, Simon AH, Pinske C. Amino acid variants of the HybB membrane subunit ofEscherichia coli[NiFe]‐hydrogenase‐2 support a role in proton transfer. FEBS Lett 2019; 593:2194-2203. [DOI: 10.1002/1873-3468.13514] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/25/2019] [Accepted: 06/25/2019] [Indexed: 11/09/2022]
Affiliation(s)
- Dorothea Lubek
- Department of Microbiology Martin‐Luther University Halle‐Wittenberg Germany
| | - Andreas H. Simon
- Department Naturstoffbiochemie, Charles Tanford Protein Centre Martin‐Luther University Halle‐Wittenberg Germany
| | - Constanze Pinske
- Department of Microbiology Martin‐Luther University Halle‐Wittenberg Germany
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13
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Hards K, Rodriguez SM, Cairns C, Cook GM. Alternate quinone coupling in a new class of succinate dehydrogenase may potentiate mycobacterial respiratory control. FEBS Lett 2019; 593:475-486. [DOI: 10.1002/1873-3468.13330] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 01/16/2019] [Indexed: 11/09/2022]
Affiliation(s)
- Kiel Hards
- Department of Microbiology and Immunology University of Otago Dunedin New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery The University of Auckland New Zealand
| | | | - Charlotte Cairns
- Department of Microbiology and Immunology University of Otago Dunedin New Zealand
| | - Gregory M. Cook
- Department of Microbiology and Immunology University of Otago Dunedin New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery The University of Auckland New Zealand
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14
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Manoj KM, Parashar A, David Jacob V, Ramasamy S. Aerobic respiration: proof of concept for the oxygen-centric murburn perspective. J Biomol Struct Dyn 2019; 37:4542-4556. [PMID: 30488771 DOI: 10.1080/07391102.2018.1552896] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The inner mitochondrial membrane protein complexes (I-V) and prokaryotic respiratory machinery are examined for a deeper understanding of their structure-function correlations and dynamics. In silico analysis of the structure of complexes I-IV, docking studies and erstwhile literature confirm that they carry sites which are in close proximity to DROS (diffusible reactive oxygen species) generating redox centers. These findings provide supportive evidence for the newly proposed oxygen-centric chemical-coupling mechanism (murburn concept), wherein DROS catalyzes the esterification of inorganic phosphate to ADP. Further, in a reductionist system, we demonstrate that a DROS (like superoxide) can effectively esterify inorganic phosphate to ADP. The impact of these findings and the interactive dynamics of classical inhibitors (rotenone and cyanide), uncouplers (dinitrophenol and uncoupling protein) and other toxins (atractyloside and oligomycin) are briefly discussed. Highlights • Earlier perception: Complexes (I-IV) pump protons and Complex V make ATP (aided by protons) • Herein: Respiratory molecular machinery is probed for new structure-function correlations • Analyses: Quantitative arguments discount proton-centric ATP synthesis in mitochondria and bacteria • In silico data: ADP-binding sites and O2/ diffusible reactive oxygen species (DROS)-accessible channels are unveiled in respiratory proteins • In vitro data: Using luminometry, ATP synthesis is demonstrated from ADP, Pi and superoxide • Inference: Findings agree with decentralized ADP-Pi activation via oxygen-centric murburn scheme Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
| | - Abhinav Parashar
- Department of Biotechnology, Vignan's Foundation for Science, Technology & Research , Vadlamudi , Guntur, Andhra Pradesh, India
| | | | - Surjith Ramasamy
- Department of Biotechnology, Indian Institute of Technology Guwahati , Guwahati , Assam, India
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15
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Structural insights into the electron/proton transfer pathways in the quinol:fumarate reductase from Desulfovibrio gigas. Sci Rep 2018; 8:14935. [PMID: 30297797 PMCID: PMC6175931 DOI: 10.1038/s41598-018-33193-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 09/18/2018] [Indexed: 11/08/2022] Open
Abstract
The membrane-embedded quinol:fumarate reductase (QFR) in anaerobic bacteria catalyzes the reduction of fumarate to succinate by quinol in the anaerobic respiratory chain. The electron/proton-transfer pathways in QFRs remain controversial. Here we report the crystal structure of QFR from the anaerobic sulphate-reducing bacterium Desulfovibrio gigas (D. gigas) at 3.6 Å resolution. The structure of the D. gigas QFR is a homo-dimer, each protomer comprising two hydrophilic subunits, A and B, and one transmembrane subunit C, together with six redox cofactors including two b-hemes. One menaquinone molecule is bound near heme bL in the hydrophobic subunit C. This location of the menaquinone-binding site differs from the menaquinol-binding cavity proposed previously for QFR from Wolinella succinogenes. The observed bound menaquinone might serve as an additional redox cofactor to mediate the proton-coupled electron transport across the membrane. Armed with these structural insights, we propose electron/proton-transfer pathways in the quinol reduction of fumarate to succinate in the D. gigas QFR.
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16
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Structure and electrochemistry of proteins harboring iron-sulfur clusters of different nuclearities. Part III. [4Fe-4S], [3Fe-4S] and [2Fe-2S] iron-sulfur proteins. J Struct Biol 2018; 202:264-274. [DOI: 10.1016/j.jsb.2018.03.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/16/2018] [Indexed: 11/18/2022]
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17
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Koppel N, Bisanz JE, Pandelia ME, Turnbaugh PJ, Balskus EP. Discovery and characterization of a prevalent human gut bacterial enzyme sufficient for the inactivation of a family of plant toxins. eLife 2018; 7:33953. [PMID: 29761785 PMCID: PMC5953540 DOI: 10.7554/elife.33953] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 04/11/2018] [Indexed: 12/21/2022] Open
Abstract
Although the human gut microbiome plays a prominent role in xenobiotic transformation, most of the genes and enzymes responsible for this metabolism are unknown. Recently, we linked the two-gene 'cardiac glycoside reductase' (cgr) operon encoded by the gut Actinobacterium Eggerthella lenta to inactivation of the cardiac medication and plant natural product digoxin. Here, we compared the genomes of 25 E. lenta strains and close relatives, revealing an expanded 8-gene cgr-associated gene cluster present in all digoxin metabolizers and absent in non-metabolizers. Using heterologous expression and in vitro biochemical characterization, we discovered that a single flavin- and [4Fe-4S] cluster-dependent reductase, Cgr2, is sufficient for digoxin inactivation. Unexpectedly, Cgr2 displayed strict specificity for digoxin and other cardenolides. Quantification of cgr2 in gut microbiomes revealed that this gene is widespread and conserved in the human population. Together, these results demonstrate that human-associated gut bacteria maintain specialized enzymes that protect against ingested plant toxins.
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Affiliation(s)
- Nitzan Koppel
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Jordan E Bisanz
- Department of Microbiology & Immunology, University of California, San Francisco, United States
| | | | - Peter J Turnbaugh
- Department of Microbiology & Immunology, University of California, San Francisco, United States.,Chan Zuckerberg Biohub, San Francisco, United States
| | - Emily P Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States.,Broad Institute, Cambridge, United States
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18
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Dash P, Bala Divya M, Guruprasad L, Guruprasad K. Three-dimensional models of Mycobacterium tuberculosis proteins Rv1555, Rv1554 and their docking analyses with sildenafil, tadalafil, vardenafil drugs, suggest interference with quinol binding likely to affect protein's function. BMC STRUCTURAL BIOLOGY 2018; 18:5. [PMID: 29669541 PMCID: PMC5907181 DOI: 10.1186/s12900-018-0085-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 04/11/2018] [Indexed: 12/14/2022]
Abstract
Background Earlier based on bioinformatics analyses, we had predicted the Mycobacterium tuberculosis (M.tb) proteins; Rv1555 and Rv1554, among the potential new tuberculosis drug targets. According to the ‘TB-drugome’ the Rv1555 protein is ‘druggable’ with sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) drugs. In the present work, we intended to understand via computer modeling studies, how the above drugs are likely to inhibit the M.tb protein’s function. Results The three-dimensional computer models for M.tb proteins; Rv1555 and Rv1554 constructed on the template of equivalent membrane anchor subunits of the homologous E.coli quinol fumarate reductase respiratory protein complex, followed by drug docking analyses, suggested that the binding of above drugs interferes with quinol binding sites. Also, we experimentally observed the in-vitro growth inhibition of E.coli bacteria containing the homologous M.tb protein sequences with sildenafil and tadalafil drugs. Conclusions The predicted binding sites of the drugs is likely to affect the above M.tb proteins function as quinol binding is known to be essential for electron transfer function during anaerobic respiration in the homologous E.coli protein complex. Therefore, sildenafil and related drugs currently used in the treatment of male erectile dysfunction targeting the human phosphodiesterase 5 enzyme may be evaluated for their plausible role as repurposed drugs to treat human tuberculosis. Electronic supplementary material The online version of this article (10.1186/s12900-018-0085-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Pallabini Dash
- Kunchur Guruprasad, Bioinformatics, Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad, 500007, India
| | - M Bala Divya
- School of Chemistry, University of Hyderabad, Gachibowli, Hyderabad, 500046, India
| | - Lalitha Guruprasad
- School of Chemistry, University of Hyderabad, Gachibowli, Hyderabad, 500046, India
| | - Kunchur Guruprasad
- Kunchur Guruprasad, Bioinformatics, Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad, 500007, India.
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19
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Starbird C, Tomasiak TM, Singh PK, Yankovskaya V, Maklashina E, Eisenbach M, Cecchini G, Iverson T. New crystal forms of the integral membrane Escherichia coli quinol:fumarate reductase suggest that ligands control domain movement. J Struct Biol 2018; 202:100-104. [PMID: 29158068 PMCID: PMC5835405 DOI: 10.1016/j.jsb.2017.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/10/2017] [Accepted: 11/12/2017] [Indexed: 01/28/2023]
Abstract
Quinol:fumarate reductase (QFR) is an integral membrane protein and a member of the respiratory Complex II superfamily. Although the structure of Escherichia coli QFR was first reported almost twenty years ago, many open questions of catalysis remain. Here we report two new crystal forms of QFR, one grown from the lipidic cubic phase and one grown from dodecyl maltoside micelles. QFR crystals grown from the lipid cubic phase processed as P1, merged to 7.5 Å resolution, and exhibited crystal packing similar to previous crystal forms. Crystals grown from dodecyl maltoside micelles processed as P21, merged to 3.35 Å resolution, and displayed a unique crystal packing. This latter crystal form provides the first view of the E. coli QFR active site without a dicarboxylate ligand. Instead, an unidentified anion binds at a shifted position. In one of the molecules in the asymmetric unit, this is accompanied by rotation of the capping domain of the catalytic subunit. In the other molecule, this is associated with loss of interpretable electron density for this same capping domain. Analysis of the structure suggests that the ligand adjusts the position of the capping domain.
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Affiliation(s)
- C.A. Starbird
- Graduate Program in Chemical and Physical Biology, Vanderbilt University, Nashville, Tennessee 37232
| | - Thomas M. Tomasiak
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232
| | - Prashant K. Singh
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232
| | - Victoria Yankovskaya
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, California 94121, Department of Biochemistry & Biophysics, University of California, San Francisco, California 94158
| | - Elena Maklashina
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, California 94121, Department of Biochemistry & Biophysics, University of California, San Francisco, California 94158
| | - Michael Eisenbach
- Department of Biomolecular Sciences, Weizmann Institute of Science, Israel
| | - Gary Cecchini
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, California 94121, Department of Biochemistry & Biophysics, University of California, San Francisco, California 94158
| | - T.M. Iverson
- Graduate Program in Chemical and Physical Biology, Vanderbilt University, Nashville, Tennessee 37232,Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232
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20
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Nóbrega CS, Devreese B, Pauleta SR. YhjA - An Escherichia coli trihemic enzyme with quinol peroxidase activity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:411-422. [PMID: 29550214 DOI: 10.1016/j.bbabio.2018.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 02/11/2018] [Accepted: 03/13/2018] [Indexed: 10/17/2022]
Abstract
The trihemic bacterial cytochrome c peroxidase from Escherichia coli, YhjA, is a membrane-anchored protein with a C-terminal domain homologous to the classical bacterial peroxidases and an additional N-terminal (NT) heme binding domain. Recombinant YhjA is a 50 kDa monomer in solution with three c-type hemes covalently bound. Here is reported the first biochemical and spectroscopic characterization of YhjA and of the NT domain demonstrating that NT heme is His63/Met125 coordinated. The reduction potentials of P (active site), NT and E hemes were established to be -170 mV, +133 mV and +210 mV, respectively, at pH 7.5. YhjA has quinol peroxidase activity in vitro with optimum activity at pH 7.0 and millimolar range KM values using hydroquinone and menadiol (a menaquinol analogue) as electron donors (KM = 0.6 ± 0.2 and 1.8 ± 0.5 mM H2O2, respectively), with similar turnover numbers (kcat = 19 ± 2 and 13 ± 2 s-1, respectively). YhjA does not require reductive activation for maximum activity, in opposition to classical bacterial peroxidases, as P heme is always high-spin 6-coordinated with a water-derived molecule as distal axial ligand but shares the need for the presence of calcium ions in the kinetic assays. Formation of a ferryl Fe(IV) = O species was observed upon incubation of fully oxidized YhjA with H2O2. The data reported improve our understanding of the biochemical properties and catalytic mechanism of YhjA, a three-heme peroxidase that uses the quinol pool to defend the cells against hydrogen peroxide during transient exposure to oxygenated environments.
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Affiliation(s)
- Cláudia S Nóbrega
- Microbial Stress Lab, UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal
| | - Bart Devreese
- Laboratory of Protein Biochemistry and Biomolecular Engineering, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Sofia R Pauleta
- Microbial Stress Lab, UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal.
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21
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Sharma P, Maklashina E, Cecchini G, Iverson TM. Crystal structure of an assembly intermediate of respiratory Complex II. Nat Commun 2018; 9:274. [PMID: 29348404 PMCID: PMC5773532 DOI: 10.1038/s41467-017-02713-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 12/20/2017] [Indexed: 02/06/2023] Open
Abstract
Flavin is covalently attached to the protein scaffold in ~10% of flavoenzymes. However, the mechanism of covalent modification is unclear, due in part to challenges in stabilizing assembly intermediates. Here, we capture the structure of an assembly intermediate of the Escherichiacoli Complex II (quinol:fumarate reductase (FrdABCD)). The structure contains the E. coli FrdA subunit bound to covalent FAD and crosslinked with its assembly factor, SdhE. The structure contains two global conformational changes as compared to prior structures of the mature protein: the rotation of a domain within the FrdA subunit, and the destabilization of two large loops of the FrdA subunit, which may create a tunnel to the active site. We infer a mechanism for covalent flavinylation. As supported by spectroscopic and kinetic analyses, we suggest that SdhE shifts the conformational equilibrium of the FrdA active site to disfavor succinate/fumarate interconversion and enhance covalent flavinylation. The mechanism for covalent flavinylation of flavoenzymes is still unclear. Here, the authors propose a mechanism based on the crystal structure of a flavinylation assembly intermediate of the E. coli respiratory Complex II comprising the E. coli FrdA subunit bound to covalent FAD and crosslinked with its assembly factor SdhE.
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Affiliation(s)
- Pankaj Sharma
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Elena Maklashina
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, CA, 94121, USA.,Department of Biochemistry & Biophysics, University of California, San Francisco, CA, 94158, USA
| | - Gary Cecchini
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, CA, 94121, USA. .,Department of Biochemistry & Biophysics, University of California, San Francisco, CA, 94158, USA.
| | - T M Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA. .,Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA. .,Center for Structural Biology, Vanderbilt University, Nashville, TN, 37232, USA. .,Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, 37232, USA.
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22
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Szamosvári D, Böttcher T. An Unsaturated Quinolone N-Oxide of Pseudomonas aeruginosa Modulates Growth and Virulence of Staphylococcus aureus. Angew Chem Int Ed Engl 2017; 56:7271-7275. [PMID: 28523838 DOI: 10.1002/anie.201702944] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Indexed: 01/15/2023]
Abstract
The pathogen Pseudomonas aeruginosa produces over 50 different quinolones, 16 of which belong to the class of 2-alkyl-4-quinolone N-oxides (AQNOs) with various chain lengths and degrees of saturation. We present the first synthesis of a previously proposed unsaturated compound that is confirmed to be present in culture extracts of P. aeruginosa, and its structure is shown to be trans-Δ1 -2-(non-1-enyl)-4-quinolone N-oxide. This compound is the most active agent against S. aureus, including MRSA strains, by more than one order of magnitude whereas its cis isomer is inactive. At lower concentrations, the compound induces small-colony variants of S. aureus, reduces the virulence by inhibiting hemolysis, and inhibits nitrate reductase activity under anaerobic conditions. These studies suggest that this unsaturated AQNO is one of the major agents that are used by P. aeruginosa to modulate competing bacterial species.
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Affiliation(s)
- Dávid Szamosvári
- Fachbereich Chemie, Konstanz Research School Chemical Biology, Zukunftskolleg, Universität Konstanz, 78457, Konstanz, Germany
| | - Thomas Böttcher
- Fachbereich Chemie, Konstanz Research School Chemical Biology, Zukunftskolleg, Universität Konstanz, 78457, Konstanz, Germany
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23
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Szamosvári D, Böttcher T. Ein ungesättigtes Chinolon-N-oxid vonPseudomonas aeruginosamoduliert Wachstum und Virulenz vonStaphylococcus aureus. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201702944] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Dávid Szamosvári
- Fachbereich Chemie, Konstanz Research School Chemical Biology, Zukunftskolleg; Universität Konstanz; 78457 Konstanz Deutschland
| | - Thomas Böttcher
- Fachbereich Chemie, Konstanz Research School Chemical Biology, Zukunftskolleg; Universität Konstanz; 78457 Konstanz Deutschland
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24
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Wong KS, Bhandari V, Janga SC, Houry WA. The RavA-ViaA Chaperone-Like System Interacts with and Modulates the Activity of the Fumarate Reductase Respiratory Complex. J Mol Biol 2017; 429:324-344. [DOI: 10.1016/j.jmb.2016.12.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 12/05/2016] [Accepted: 12/05/2016] [Indexed: 01/02/2023]
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25
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Maklashina E, Rajagukguk S, Starbird CA, McDonald WH, Koganitsky A, Eisenbach M, Iverson TM, Cecchini G. Binding of the Covalent Flavin Assembly Factor to the Flavoprotein Subunit of Complex II. J Biol Chem 2015; 291:2904-16. [PMID: 26644464 DOI: 10.1074/jbc.m115.690396] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Indexed: 01/23/2023] Open
Abstract
Escherichia coli harbors two highly conserved homologs of the essential mitochondrial respiratory complex II (succinate:ubiquinone oxidoreductase). Aerobically the bacterium synthesizes succinate:quinone reductase as part of its respiratory chain, whereas under microaerophilic conditions, the quinol:fumarate reductase can be utilized. All complex II enzymes harbor a covalently bound FAD co-factor that is essential for their ability to oxidize succinate. In eukaryotes and many bacteria, assembly of the covalent flavin linkage is facilitated by a small protein assembly factor, termed SdhE in E. coli. How SdhE assists with formation of the covalent flavin bond and how it binds the flavoprotein subunit of complex II remain unknown. Using photo-cross-linking, we report the interaction site between the flavoprotein of complex II and the SdhE assembly factor. These data indicate that SdhE binds to the flavoprotein between two independently folded domains and that this binding mode likely influences the interdomain orientation. In so doing, SdhE likely orients amino acid residues near the dicarboxylate and FAD binding site, which facilitates formation of the covalent flavin linkage. These studies identify how the conserved SdhE assembly factor and its homologs participate in complex II maturation.
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Affiliation(s)
- Elena Maklashina
- From the Molecular Biology Division, Veterans Affairs Medical Center, San Francisco, California 94121, the Department of Biochemistry & Biophysics, University of California, San Francisco, California 94158
| | - Sany Rajagukguk
- From the Molecular Biology Division, Veterans Affairs Medical Center, San Francisco, California 94121
| | | | - W Hayes McDonald
- the Department of Biochemistry and Mass Spectrometry Research Center
| | - Anna Koganitsky
- the Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Michael Eisenbach
- the Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Tina M Iverson
- the Department of Biochemistry and Mass Spectrometry Research Center, the Department of Pharmacology, the Center for Structural Biology, and the Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, and
| | - Gary Cecchini
- From the Molecular Biology Division, Veterans Affairs Medical Center, San Francisco, California 94121, the Department of Biochemistry & Biophysics, University of California, San Francisco, California 94158,
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Abstract
Escherichia coli is a versatile facultative anaerobe that can respire on a number of terminal electron acceptors, including oxygen, fumarate, nitrate, and S- and N-oxides. Anaerobic respiration using S- and N-oxides is accomplished by enzymatic reduction of these substrates by dimethyl sulfoxide reductase (DmsABC) and trimethylamine N-oxide reductase (TorCA). Both DmsABC and TorCA are membrane-associated redox enzymes that couple the oxidation of menaquinol to the reduction of S- and N-oxides in the periplasm. DmsABC is membrane bound and is composed of a membrane-extrinsic dimer with a 90.4-kDa catalytic subunit (DmsA) and a 23.1-kDa electron transfer subunit (DmsB). These subunits face the periplasm and are held to the membrane by a 30.8-kDa membrane anchor subunit (DmsC). The enzyme provides the scaffold for an electron transfer relay composed of a quinol binding site, five [4Fe-4S] clusters, and a molybdo-bis(molybdopterin guanine dinucleotide) (present nomenclature: Mo-bis-pyranopterin) (Mo-bisMGD) cofactor. TorCA is composed of a soluble periplasmic subunit (TorA, 92.5 kDa) containing a Mo-bis-MGD. TorA is coupled to the quinone pool via a pentaheme c subunit (TorC, 40.4 kDa) in the membrane. Both DmsABC and TorCA require system-specific chaperones (DmsD or TorD) for assembly, cofactor insertion, and/or targeting to the Tat translocon. In this chapter, we discuss the complex regulation of the dmsABC and torCAD operons, the poorly understood paralogues, and what is known about the assembly and translocation to the periplasmic space by the Tat translocon.
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Structural Insights into the Molecular Design of Flutolanil Derivatives Targeted for Fumarate Respiration of Parasite Mitochondria. Int J Mol Sci 2015. [PMID: 26198225 PMCID: PMC4519900 DOI: 10.3390/ijms160715287] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Recent studies on the respiratory chain of Ascaris suum showed that the mitochondrial NADH-fumarate reductase system composed of complex I, rhodoquinone and complex II plays an important role in the anaerobic energy metabolism of adult A. suum. The system is the major pathway of energy metabolism for adaptation to a hypoxic environment not only in parasitic organisms, but also in some types of human cancer cells. Thus, enzymes of the pathway are potential targets for chemotherapy. We found that flutolanil is an excellent inhibitor for A. suum complex II (IC50 = 0.058 μM) but less effectively inhibits homologous porcine complex II (IC50 = 45.9 μM). In order to account for the specificity of flutolanil to A. suum complex II from the standpoint of structural biology, we determined the crystal structures of A. suum and porcine complex IIs binding flutolanil and its derivative compounds. The structures clearly demonstrated key interactions responsible for its high specificity to A. suum complex II and enabled us to find analogue compounds, which surpass flutolanil in both potency and specificity to A. suum complex II. Structures of complex IIs binding these compounds will be helpful to accelerate structure-based drug design targeted for complex IIs.
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Cheng VWT, Piragasam RS, Rothery RA, Maklashina E, Cecchini G, Weiner JH. Redox state of flavin adenine dinucleotide drives substrate binding and product release in Escherichia coli succinate dehydrogenase. Biochemistry 2015; 54:1043-52. [PMID: 25569225 DOI: 10.1021/bi501350j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The Complex II family of enzymes, comprising respiratory succinate dehydrogenases and fumarate reductases, catalyzes reversible interconversion of succinate and fumarate. In contrast to the covalent flavin adenine dinucleotide (FAD) cofactor assembled in these enzymes, soluble fumarate reductases (e.g., those from Shewanella frigidimarina) that assemble a noncovalent FAD cannot catalyze succinate oxidation but retain the ability to reduce fumarate. In this study, an SdhA-H45A variant that eliminates the site of the 8α-N3-histidyl covalent linkage between the protein and FAD was examined. Variants SdhA-R286A/K/Y and -H242A/Y that target residues thought to be important for substrate binding and catalysis were also studied. The variants SdhA-H45A and -R286A/K/Y resulted in the assembly of a noncovalent FAD cofactor, which led to a significant decrease (-87 mV or more) in its reduction potential. The variant enzymes were studied by electron paramagnetic resonance spectroscopy following stand-alone reduction and potentiometric titrations. The "free" and "occupied" states of the active site were linked to the reduced and oxidized states of FAD, respectively. Our data allow for a proposed model of succinate oxidation that is consistent with tunnel diode effects observed in the succinate dehydrogenase enzyme and a preference for fumarate reduction catalysis in fumarate reductase homologues that assemble a noncovalent FAD.
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Affiliation(s)
- Victor W T Cheng
- Department of Biochemistry, University of Alberta , Edmonton, Alberta T6G 2H7, Canada
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29
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Zanello P. The competition between chemistry and biology in assembling iron–sulfur derivatives. Molecular structures and electrochemistry. Part II. {[Fe2S2](SγCys)4} proteins. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2014.08.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Estellon J, Ollagnier de Choudens S, Smadja M, Fontecave M, Vandenbrouck Y. An integrative computational model for large-scale identification of metalloproteins in microbial genomes: a focus on iron-sulfur cluster proteins. Metallomics 2014; 6:1913-30. [PMID: 25117543 DOI: 10.1039/c4mt00156g] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Metalloproteins represent a ubiquitous group of molecules which are crucial to the survival of all living organisms. While several metal-binding motifs have been defined, it remains challenging to confidently identify metalloproteins from primary protein sequences using computational approaches alone. Here, we describe a comprehensive strategy based on a machine learning approach to design and assess a penalized generalized linear model. We used this strategy to detect members of the iron-sulfur cluster protein family. A new category of descriptors, whose profile is based on profile hidden Markov models, encoding structural information was combined with public descriptors into a linear model. The model was trained and tested on distinct datasets composed of well-characterized iron-sulfur protein sequences, and the resulting model provided higher sensitivity compared to a motif-based approach, while maintaining a good level of specificity. Analysis of this linear model allows us to detect and quantify the contribution of each descriptor, providing us with a better understanding of this complex protein family along with valuable indications for further experimental characterization. Two newly-identified proteins, YhcC and YdiJ, were functionally validated as genuine iron-sulfur proteins, confirming the prediction. The computational model was then applied to over 550 prokaryotic genomes to screen for iron-sulfur proteomes; the results are publicly available at: . This study represents a proof-of-concept for the application of a penalized linear model to identify metalloprotein superfamilies on a large-scale. The application employed here, screening for iron-sulfur proteomes, provides new candidates for further biochemical and structural analysis as well as new resources for an extensive exploration of iron-sulfuromes in the microbial world.
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Affiliation(s)
- Johan Estellon
- Univ. Grenoble Alpes, iRTSV-BGE, F-38000 Grenoble, France.
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Essentiality of succinate dehydrogenase in Mycobacterium smegmatis and its role in the generation of the membrane potential under hypoxia. mBio 2014; 5:mBio.01093-14. [PMID: 25118234 PMCID: PMC4145680 DOI: 10.1128/mbio.01093-14] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Succinate:quinone oxidoreductase (Sdh) is a membrane-bound complex that couples the oxidation of succinate to fumarate in the cytoplasm to the reduction of quinone to quinol in the membrane. Mycobacterial species harbor genes for two putative sdh operons, but the individual roles of these two operons are unknown. In this communication, we show that Mycobacterium smegmatis mc2155 expresses two succinate dehydrogenases designated Sdh1 and Sdh2. Sdh1 is encoded by a five-gene operon (MSMEG_0416-MSMEG_0420), and Sdh2 is encoded by a four-gene operon (MSMEG_1672-MSMEG_1669). These two operons are differentially expressed in response to carbon limitation, hypoxia, and fumarate, as monitored by sdh promoter-lacZ fusions. While deletion of the sdh1 operon did not yield any growth phenotypes on succinate or other nonfermentable carbon sources, the sdh2 operon could be deleted only in a merodiploid background, demonstrating that Sdh2 is essential for growth. Sdh activity and succinate-dependent proton pumping were detected in cells grown aerobically, as well as under hypoxia. Fumarate reductase activity was absent under these conditions, indicating that neither Sdh1 nor Sdh2 could catalyze the reverse reaction. Sdh activity was inhibited by the Sdh inhibitor 3-nitroproprionate (3NP), and treatment with 3NP dissipated the membrane potential of wild-type or Δsdh1 mutant cells under hypoxia but not that of cells grown aerobically. These data imply that Sdh2 is the generator of the membrane potential under hypoxia, an essential role for the cell. Complex II or succinate dehydrogenase (Sdh) is a major respiratory enzyme that couples the oxidation of succinate to fumarate in the cytoplasm to the reduction of quinone to quinol in the membrane. Mycobacterial species harbor genes for two putative sdh operons, sdh1 and sdh2, but the individual roles of these two operons are unknown. In this communication, we show that sdh1 and sdh2 are differentially expressed in response to energy limitation, oxygen tension, and alternative electron acceptor availability, suggesting distinct functional cellular roles. Sdh2 was essential for growth and generation of the membrane potential in hypoxic cells. Given the essentiality of succinate dehydrogenase and oxidative phosphorylation in the growth cycle of Mycobacterium tuberculosis, the potential exists to develop new antituberculosis agents against the mycobacterial succinate dehydrogenase. This enzyme has been proposed as a potential target for the development of new chemotherapeutic agents against intracellular parasites and mitochondrion-associated disease.
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Hellwig P. Infrared spectroscopic markers of quinones in proteins from the respiratory chain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:126-33. [PMID: 25026472 DOI: 10.1016/j.bbabio.2014.07.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/03/2014] [Accepted: 07/07/2014] [Indexed: 01/12/2023]
Abstract
In bioenergetic systems quinones play a central part in the coupling of electron and proton transfer. The specific function of each quinone binding site is based on the protein-quinone interaction that can be described by means of reaction induced FTIR difference spectroscopy, induced for example by light or electrochemically. The identification of sites in enzymes from the respiratory chain is presented together with the analysis of the accommodation of different types of quinones to the same enzyme and the possibility to monitor the interaction with inhibitors. Reaction induced FTIR difference spectroscopy is shown to give an essential information on the general geometry of quinone binding sites, the conformation of the ring and of the substituents as well as essential structural information on the identity of the amino-acid residues lining this site. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
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Affiliation(s)
- Petra Hellwig
- Laboratoire de bioélectrochimie et spectroscopie, UMR 7140, Chimie de la matière complexe, Université de Strasbourg, 1, rue Blaise Pascal, 67008 Strasbourg, France.
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Abstract
Efforts from the TB Structural Genomics Consortium together with those of tuberculosis structural biologists worldwide have led to the determination of about 350 structures, making up nearly a tenth of the pathogen's proteome. Given that knowledge of protein structures is essential to obtaining a high-resolution understanding of the underlying biology, it is desirable to have a structural view of the entire proteome. Indeed, structure prediction methods have advanced sufficiently to allow structural models of many more proteins to be built based on homology modeling and fold recognition strategies. By means of these approaches, structural models for about 2,877 proteins, making up nearly 70% of the Mycobacterium tuberculosis proteome, are available. Knowledge from bioinformatics has made significant inroads into an improved annotation of the M. tuberculosis genome and in the prediction of key protein players that interact in vital pathways, some of which are unique to the organism. Functional inferences have been made for a large number of proteins based on fold-function associations. More importantly, ligand-binding pockets of the proteins are identified and scanned against a large database, leading to binding site-based ligand associations and hence structure-based function annotation. Near proteome-wide structural models provide a global perspective of the fold distribution in the genome. New insights about the folds that predominate in the genome, as well as the fold combinations that make up multidomain proteins, are also obtained. This chapter describes the structural proteome, functional inferences drawn from it, and its applications in drug discovery.
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34
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Sun F, Zhou Q, Pang X, Xu Y, Rao Z. Revealing various coupling of electron transfer and proton pumping in mitochondrial respiratory chain. Curr Opin Struct Biol 2013; 23:526-38. [DOI: 10.1016/j.sbi.2013.06.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/13/2013] [Accepted: 06/19/2013] [Indexed: 01/23/2023]
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Wang H, He Z, Zhang C, Zhang L, Xu D. Transmembrane protein alignment and fold recognition based on predicted topology. PLoS One 2013; 8:e69744. [PMID: 23894534 PMCID: PMC3716705 DOI: 10.1371/journal.pone.0069744] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 06/15/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Although Transmembrane Proteins (TMPs) are highly important in various biological processes and pharmaceutical developments, general prediction of TMP structures is still far from satisfactory. Because TMPs have significantly different physicochemical properties from soluble proteins, current protein structure prediction tools for soluble proteins may not work well for TMPs. With the increasing number of experimental TMP structures available, template-based methods have the potential to become broadly applicable for TMP structure prediction. However, the current fold recognition methods for TMPs are not as well developed as they are for soluble proteins. METHODOLOGY We developed a novel TMP Fold Recognition method, TMFR, to recognize TMP folds based on sequence-to-structure pairwise alignment. The method utilizes topology-based features in alignment together with sequence profile and solvent accessibility. It also incorporates a gap penalty that depends on predicted topology structure segments. Given the difference between α-helical transmembrane protein (αTMP) and β-strands transmembrane protein (βTMP), parameters of scoring functions are trained respectively for these two protein categories using 58 αTMPs and 17 βTMPs in a non-redundant training dataset. RESULTS We compared our method with HHalign, a leading alignment tool using a non-redundant testing dataset including 72 αTMPs and 30 βTMPs. Our method achieved 10% and 9% better accuracies than HHalign in αTMPs and βTMPs, respectively. The raw score generated by TMFR is negatively correlated with the structure similarity between the target and the template, which indicates its effectiveness for fold recognition. The result demonstrates TMFR provides an effective TMP-specific fold recognition and alignment method.
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Affiliation(s)
- Han Wang
- School of Computer Science and Information Technology, Northeast Normal University, Changchun, People’s Republic of China
- Department of Computer Science, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
| | - Zhiquan He
- Department of Computer Science, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
| | - Chao Zhang
- Department of Computer Science, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
| | - Li Zhang
- School of Computer Science and Engineering, Changchun University of Technology, Changchun, People’s Republic of China
| | - Dong Xu
- Department of Computer Science, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
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36
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Singh PK, Sarwar M, Maklashina E, Kotlyar V, Rajagukguk S, Tomasiak TM, Cecchini G, Iverson TM. Plasticity of the quinone-binding site of the complex II homolog quinol:fumarate reductase. J Biol Chem 2013; 288:24293-301. [PMID: 23836905 DOI: 10.1074/jbc.m113.487082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Respiratory processes often use quinone oxidoreduction to generate a transmembrane proton gradient, making the 2H(+)/2e(-) quinone chemistry important for ATP synthesis. There are a variety of quinones used as electron carriers between bioenergetic proteins, and some respiratory proteins can functionally interact with more than one quinone type. In the case of complex II homologs, which couple quinone chemistry to the interconversion of succinate and fumarate, the redox potentials of the biologically available ubiquinone and menaquinone aid in driving the chemical reaction in one direction. In the complex II homolog quinol:fumarate reductase, it has been demonstrated that menaquinol oxidation requires at least one proton shuttle, but many of the remaining mechanistic details of menaquinol oxidation are not fully understood, and little is known about ubiquinone reduction. In the current study, structural and computational studies suggest that the sequential removal of the two menaquinol protons may be accompanied by a rotation of the naphthoquinone ring to optimize the interaction with a second proton shuttling pathway. However, kinetic measurements of site-specific mutations of quinol:fumarate reductase variants show that ubiquinone reduction does not use the same pathway. Computational docking of ubiquinone followed by mutagenesis instead suggested redundant proton shuttles lining the ubiquinone-binding site or from direct transfer from solvent. These data show that the quinone-binding site provides an environment that allows multiple amino acid residues to participate in quinone oxidoreduction. This suggests that the quinone-binding site in complex II is inherently plastic and can robustly interact with different types of quinones.
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Affiliation(s)
- Prashant K Singh
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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37
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Cheng VWT, Tran QM, Boroumand N, Rothery RA, Maklashina E, Cecchini G, Weiner JH. A conserved lysine residue controls iron-sulfur cluster redox chemistry in Escherichia coli fumarate reductase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:1141-7. [PMID: 23711795 DOI: 10.1016/j.bbabio.2013.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 05/10/2013] [Accepted: 05/14/2013] [Indexed: 11/16/2022]
Abstract
The Escherichia coli respiratory complex II paralogs succinate dehydrogenase (SdhCDAB) and fumarate reductase (FrdABCD) catalyze interconversion of succinate and fumarate coupled to quinone reduction or oxidation, respectively. Based on structural comparison of the two enzymes, equivalent residues at the interface between the highly homologous soluble domains and the divergent membrane anchor domains were targeted for study. This included the residue pair SdhB-R205 and FrdB-S203, as well as the conserved SdhB-K230 and FrdB-K228 pair. The close proximity of these residues to the [3Fe-4S] cluster and the quinone binding pocket provided an excellent opportunity to investigate factors controlling the reduction potential of the [3Fe-4S] cluster, the directionality of electron transfer and catalysis, and the architecture and chemistry of the quinone binding sites. Our results indicate that both SdhB-R205 and SdhB-K230 play important roles in fine tuning the reduction potential of both the [3Fe-4S] cluster and the heme. In FrdABCD, mutation of FrdB-S203 did not alter the reduction potential of the [3Fe-4S] cluster, but removal of the basic residue at FrdB-K228 caused a significant downward shift (>100mV) in potential. The latter residue is also indispensable for quinone binding and enzyme activity. The differences observed for the FrdB-K228 and Sdh-K230 variants can be attributed to the different locations of the quinone binding site in the two paralogs. Although this residue is absolutely conserved, they have diverged to achieve different functions in Frd and Sdh.
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Affiliation(s)
- Victor W T Cheng
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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HdrC2 from Acidithiobacillus ferrooxidans owns two iron-sulfur binding motifs but binds only one variable cluster between [4Fe-4S] and [3Fe-4S]. Curr Microbiol 2012; 66:88-95. [PMID: 23053491 DOI: 10.1007/s00284-012-0244-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 09/20/2012] [Indexed: 10/27/2022]
Abstract
The heterodisulfide reductase complex HdrABC from Acidithiobacillus ferrooxidans was suggested to own novel features that act in reverse to convert the sulfane sulfur of GS( n )H species (n > 1) into sulfite in sulfur oxidation. The HdrC subunit is potentially encoded by two different highly upregulated genes sharing only 29 % identity in A. ferrooxidans grown in sulfur-containing medium, which were named as HdrC1 and HdrC2, respectively and had been confirmed to contain iron-sulfur cluster by expression and characterization, especially the HdrC1 which had been showed to bind only one [4Fe-4S] cluster by mutations. However, the mutations of the HdrC2 remain to be done and the detailed binding information of it is still unclear. Here, we report the expression, mutations, and molecular modeling of the HdrC2 from A. ferrooxidans. This HdrC2 had two identical motifs (Cx(2)Cx(2)Cx(3)C) containing total of eight cysteine residues potentially for iron-sulfur cluster binding. This purified HdrC2 was exhibited to contain one variable cluster converted between [4Fe-4S] and [3Fe-4S] according to different conditions by the UV-scanning and EPR spectra. The site-directed mutagenesis results of these eight residues further confirmed that the HdrC2 in reduction with Fe(2+) condition loaded only one [4Fe-4S](+) with spin S = 1/2 ligated by the residues of Cys73, Cys109, Cys112, and Cys115; the HdrC2 in natural aeration condition lost the Fe atom ligated by the residue of Cys73 and loaded only one [3Fe-4S](0) with spin S = 0; the HdrC2 in oxidation condition loaded only one [3Fe-4S](+) with spin S = 1/2. Molecular modeling results were also in line with the experiment results.
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Iverson TM. Catalytic mechanisms of complex II enzymes: a structural perspective. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:648-57. [PMID: 22995215 DOI: 10.1016/j.bbabio.2012.09.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 09/07/2012] [Accepted: 09/10/2012] [Indexed: 11/25/2022]
Abstract
Over a decade has passed since the elucidation of the first X-ray crystal structure of any complex II homolog. In the intervening time, the structures of five additional integral-membrane complex II enzymes and three homologs of the soluble domain have been determined. These structures have provided a framework for the analysis of enzymological studies of complex II superfamily enzymes, and have contributed to detailed proposals for reaction mechanisms at each of the two enzyme active sites, which catalyze dicarboxylate and quinone oxidoreduction, respectively. This review focuses on how structural data have augmented our understanding of catalysis by the superfamily. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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Affiliation(s)
- T M Iverson
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232-6600, USA.
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van Oosterwijk N, Knol J, Dijkhuizen L, van der Geize R, Dijkstra BW. Structure and catalytic mechanism of 3-ketosteroid-Delta4-(5α)-dehydrogenase from Rhodococcus jostii RHA1 genome. J Biol Chem 2012; 287:30975-83. [PMID: 22833669 DOI: 10.1074/jbc.m112.374306] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
3-Ketosteroid Δ4-(5α)-dehydrogenases (Δ4-(5α)-KSTDs) are enzymes that introduce a double bond between the C4 and C5 atoms of 3-keto-(5α)-steroids. Here we show that the ro05698 gene from Rhodococcus jostii RHA1 codes for a flavoprotein with Δ4-(5α)-KSTD activity. The 1.6 Å resolution crystal structure of the enzyme revealed three conserved residues (Tyr-319, Tyr-466, and Ser-468) in a pocket near the isoalloxazine ring system of the FAD co-factor. Site-directed mutagenesis of these residues confirmed that they are absolutely essential for catalytic activity. A crystal structure with bound product 4-androstene-3,17-dione showed that Ser-468 is in a position in which it can serve as the base abstracting the 4β-proton from the C4 atom of the substrate. Ser-468 is assisted by Tyr-319, which possibly is involved in shuttling the proton to the solvent. Tyr-466 is at hydrogen bonding distance to the C3 oxygen atom of the substrate and can stabilize the keto-enol intermediate occurring during the reaction. Finally, the FAD N5 atom is in a position to be able to abstract the 5α-hydrogen of the substrate as a hydride ion. These features fully explain the reaction catalyzed by Δ4-(5α)-KSTDs.
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Affiliation(s)
- Niels van Oosterwijk
- Laboratory of Biophysical Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
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Zhou Q, Zhai Y, Lou J, Liu M, Pang X, Sun F. Thiabendazole inhibits ubiquinone reduction activity of mitochondrial respiratory complex II via a water molecule mediated binding feature. Protein Cell 2011; 2:531-42. [PMID: 21822798 DOI: 10.1007/s13238-011-1079-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 07/19/2011] [Indexed: 10/17/2022] Open
Abstract
The mitochondrial respiratory complex II or succinate: ubiquinone oxidoreductase (SQR) is a key membrane complex in both the tricarboxylic acid cycle and aerobic respiration. Five disinfectant compounds were investigated with their potent inhibition effects on the ubiquinone reduction activity of the porcine mitochondrial SQR by enzymatic assay and crystallography. Crystal structure of the SQR bound with thiabendazole (TBZ) reveals a different inhibitor-binding feature at the ubiquinone binding site where a water molecule plays an important role. The obvious inhibitory effect of TBZ based on the biochemical data (IC(50) ~100 μmol/L) and the significant structure-based binding affinity calculation (~94 μmol/L) draw the suspicion of using TBZ as a good disinfectant compound for nematode infections treatment and fruit storage.
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Affiliation(s)
- Qiangjun Zhou
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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Tomasiak TM, Archuleta TL, Andréll J, Luna-Chávez C, Davis TA, Sarwar M, Ham AJ, McDonald WH, Yankovskaya V, Stern HA, Johnston JN, Maklashina E, Cecchini G, Iverson TM. Geometric restraint drives on- and off-pathway catalysis by the Escherichia coli menaquinol:fumarate reductase. J Biol Chem 2010; 286:3047-56. [PMID: 21098488 DOI: 10.1074/jbc.m110.192849] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Complex II superfamily members catalyze the kinetically difficult interconversion of succinate and fumarate. Due to the relative simplicity of complex II substrates and their similarity to other biologically abundant small molecules, substrate specificity presents a challenge in this system. In order to identify determinants for on-pathway catalysis, off-pathway catalysis, and enzyme inhibition, crystal structures of Escherichia coli menaquinol:fumarate reductase (QFR), a complex II superfamily member, were determined bound to the substrate, fumarate, and the inhibitors oxaloacetate, glutarate, and 3-nitropropionate. Optical difference spectroscopy and computational modeling support a model where QFR twists the dicarboxylate, activating it for catalysis. Orientation of the C2-C3 double bond of activated fumarate parallel to the C(4a)-N5 bond of FAD allows orbital overlap between the substrate and the cofactor, priming the substrate for nucleophilic attack. Off-pathway catalysis, such as the conversion of malate to oxaloacetate or the activation of the toxin 3-nitropropionate may occur when inhibitors bind with a similarly activated bond in the same position. Conversely, inhibitors that do not orient an activatable bond in this manner, such as glutarate and citrate, are excluded from catalysis and act as inhibitors of substrate binding. These results support a model where electronic interactions via geometric constraint and orbital steering underlie catalysis by QFR.
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Affiliation(s)
- Thomas M Tomasiak
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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Itzhaki Z, Akiva E, Margalit H. Preferential use of protein domain pairs as interaction mediators: order and transitivity. Bioinformatics 2010; 26:2564-70. [DOI: 10.1093/bioinformatics/btq495] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Maklashina E, Cecchini G. The quinone-binding and catalytic site of complex II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1877-82. [PMID: 20175986 DOI: 10.1016/j.bbabio.2010.02.015] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2009] [Revised: 02/08/2010] [Accepted: 02/16/2010] [Indexed: 10/19/2022]
Abstract
The complex II family of proteins includes succinate:quinone oxidoreductase (SQR) and quinol:fumarate oxidoreductase (QFR). In the facultative bacterium Escherichia coli both are expressed as part of the aerobic (SQR) and anaerobic (QFR) respiratory chains. SQR from E. coli is homologous to mitochondrial complex II and has proven to be an excellent model system for structure/function studies of the enzyme. Both SQR and QFR from E. coli are tetrameric membrane-bound enzymes that couple succinate/fumarate interconversion with quinone/quinol reduction/oxidation. Both enzymes are capable of binding either ubiquinone or menaquinone, however, they have adopted different quinone binding sites where catalytic reactions with quinones occur. A comparison of the structures of the quinone binding sites in SQR and QFR reveals how the enzymes have adapted in order to accommodate both benzo- and napthoquinones. A combination of structural, computational, and kinetic studies of members of the complex II family of enzymes has revealed that the catalytic quinone adopts different positions in the quinone-binding pocket. These data suggest that movement of the quinone within the quinone-binding pocket is essential for catalysis.
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Affiliation(s)
- Elena Maklashina
- Molecular Biology Division, VA Medical Center, San Francisco, CA 94121, USA
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Cammack R, MacMillan F. Electron Magnetic Resonance of Iron–Sulfur Proteins in Electron-Transfer Chains: Resolving Complexity. METALS IN BIOLOGY 2010. [DOI: 10.1007/978-1-4419-1139-1_2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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46
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Crystal structure of Adenylylsulfate reductase from Desulfovibrio gigas suggests a potential self-regulation mechanism involving the C terminus of the beta-subunit. J Bacteriol 2009; 191:7597-608. [PMID: 19820092 DOI: 10.1128/jb.00583-09] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adenylylsulfate reductase (adenosine 5'-phosphosulfate [APS] reductase [APSR]) plays a key role in catalyzing APS to sulfite in dissimilatory sulfate reduction. Here, we report the crystal structure of APSR from Desulfovibrio gigas at 3.1-A resolution. Different from the alpha(2)beta(2)-heterotetramer of the Archaeoglobus fulgidus, the overall structure of APSR from D. gigas comprises six alphabeta-heterodimers that form a hexameric structure. The flavin adenine dinucleotide is noncovalently attached to the alpha-subunit, and two [4Fe-4S] clusters are enveloped by cluster-binding motifs. The substrate-binding channel in D. gigas is wider than that in A. fulgidus because of shifts in the loop (amino acid 326 to 332) and the alpha-helix (amino acid 289 to 299) in the alpha-subunit. The positively charged residue Arg160 in the structure of D. gigas likely replaces the role of Arg83 in that of A. fulgidus for the recognition of substrates. The C-terminal segment of the beta-subunit wraps around the alpha-subunit to form a functional unit, with the C-terminal loop inserted into the active-site channel of the alpha-subunit from another alphabeta-heterodimer. Electrostatic interactions between the substrate-binding residue Arg282 in the alpha-subunit and Asp159 in the C terminus of the beta-subunit affect the binding of the substrate. Alignment of APSR sequences from D. gigas and A. fulgidus shows the largest differences toward the C termini of the beta-subunits, and structural comparison reveals notable differences at the C termini, activity sites, and other regions. The disulfide comprising Cys156 to Cys162 stabilizes the C-terminal loop of the beta-subunit and is crucial for oligomerization. Dynamic light scattering and ultracentrifugation measurements reveal multiple forms of APSR upon the addition of AMP, indicating that AMP binding dissociates the inactive hexamer into functional dimers, presumably by switching the C terminus of the beta-subunit away from the active site. The crystal structure of APSR, together with its oligomerization properties, suggests that APSR from sulfate-reducing bacteria might self-regulate its activity through the C terminus of the beta-subunit.
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Juhnke HD, Hiltscher H, Nasiri HR, Schwalbe H, Lancaster CRD. Production, characterization and determination of the real catalytic properties of the putative 'succinate dehydrogenase' from Wolinella succinogenes. Mol Microbiol 2008; 71:1088-101. [PMID: 19170876 PMCID: PMC2680327 DOI: 10.1111/j.1365-2958.2008.06581.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Both the genomes of the epsilonproteobacteria Wolinella succinogenes and Campylobacter jejuni contain operons (sdhABE) that encode for so far uncharacterized enzyme complexes annotated as ‘non-classical’ succinate:quinone reductases (SQRs). However, the role of such an enzyme ostensibly involved in aerobic respiration in an anaerobic organism such as W. succinogenes has hitherto been unknown. We have established the first genetic system for the manipulation and production of a member of the non-classical succinate:quinone oxidoreductase family. Biochemical characterization of the W. succinogenes enzyme reveals that the putative SQR is in fact a novel methylmenaquinol:fumarate reductase (MFR) with no detectable succinate oxidation activity, clearly indicative of its involvement in anaerobic metabolism. We demonstrate that the hydrophilic subunits of the MFR complex are, in contrast to all other previously characterized members of the superfamily, exported into the periplasm via the twin-arginine translocation (tat)-pathway. Furthermore we show that a single amino acid exchange (Ala86→His) in the flavoprotein of that enzyme complex is the only additional requirement for the covalent binding of the otherwise non-covalently bound FAD. Our results provide an explanation for the previously published puzzling observation that the C. jejuni sdhABE operon is upregulated in an oxygen-limited environment as compared with microaerophilic laboratory conditions.
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Affiliation(s)
- Hanno D Juhnke
- Cluster of Excellence 'Macromolecular Complexes', Max Planck Institute of Biophysics, Department of Molecular Membrane Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt am Main, Germany
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Weiner JH, Li L. Proteome of the Escherichia coli envelope and technological challenges in membrane proteome analysis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1698-713. [PMID: 17904518 DOI: 10.1016/j.bbamem.2007.07.020] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Revised: 07/19/2007] [Accepted: 07/23/2007] [Indexed: 11/28/2022]
Abstract
The envelope of Escherichia coli is a complex organelle composed of the outer membrane, periplasm-peptidoglycan layer and cytoplasmic membrane. Each compartment has a unique complement of proteins, the proteome. Determining the proteome of the envelope is essential for developing an in silico bacterial model, for determining cellular responses to environmental alterations, for determining the function of proteins encoded by genes of unknown function and for development and testing of new experimental technologies such as mass spectrometric methods for identifying and quantifying hydrophobic proteins. The availability of complete genomic information has led several groups to develop computer algorithms to predict the proteome of each part of the envelope by searching the genome for leader sequences, beta-sheet motifs and stretches of alpha-helical hydrophobic amino acids. In addition, published experimental data has been mined directly and by machine learning approaches. In this review we examine the somewhat confusing available literature and relate published experimental data to the most recent gene annotation of E. coli to describe the predicted and experimental proteome of each compartment. The problem of characterizing integral versus membrane-associated proteins is discussed. The E. coli envelope proteome provides an excellent test bed for developing mass spectrometric techniques for identifying hydrophobic proteins that have generally been refractory to analysis. We describe the gel based and solution based proteome analysis approaches along with protein cleavage and proteolysis methods that investigators are taking to tackle this difficult problem.
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Affiliation(s)
- Joel H Weiner
- Membrane Protein Research Group and The Institute for Biomolecular Design, University of Alberta, Canada.
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Quinol Oxidation by c-Type Cytochromes: Structural Characterization of the Menaquinol Binding Site of NrfHA. J Mol Biol 2008; 381:341-50. [DOI: 10.1016/j.jmb.2008.05.066] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 05/15/2008] [Accepted: 05/20/2008] [Indexed: 11/18/2022]
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50
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Tomasiak TM, Maklashina E, Cecchini G, Iverson TM. A threonine on the active site loop controls transition state formation in Escherichia coli respiratory complex II. J Biol Chem 2008; 283:15460-8. [PMID: 18385138 PMCID: PMC2397489 DOI: 10.1074/jbc.m801372200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 03/26/2008] [Indexed: 11/06/2022] Open
Abstract
In Escherichia coli, the complex II superfamily members succinate:ubiquinone oxidoreductase (SQR) and quinol:fumarate reductase (QFR) participate in aerobic and anaerobic respiration, respectively. Complex II enzymes catalyze succinate and fumarate interconversion at the interface of two domains of the soluble flavoprotein subunit, the FAD binding domain and the capping domain. An 11-amino acid loop in the capping domain (Thr-A234 to Thr-A244 in quinol:fumarate reductase) begins at the interdomain hinge and covers the active site. Amino acids of this loop interact with both the substrate and a proton shuttle, potentially coordinating substrate binding and the proton shuttle protonation state. To assess the loop's role in catalysis, two threonine residues were mutated to alanine: QFR Thr-A244 (act-T; Thr-A254 in SQR), which hydrogen-bonds to the substrate at the active site, and QFR Thr-A234 (hinge-T; Thr-A244 in SQR), which is located at the hinge and hydrogen-bonds the proton shuttle. Both mutations impair catalysis and decrease substrate binding. The crystal structure of the hinge-T mutation reveals a reorientation between the FAD-binding and capping domains that accompanies proton shuttle alteration. Taken together, hydrogen bonding from act-T to substrate may coordinate with interdomain motions to twist the double bond of fumarate and introduce the strain important for attaining the transition state.
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Affiliation(s)
- Thomas M. Tomasiak
- Departments of Pharmacology and Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, the Molecular Biology Division, Veterans Affairs Medical Center, San Francisco, California 94121, and the Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158
| | - Elena Maklashina
- Departments of Pharmacology and Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, the Molecular Biology Division, Veterans Affairs Medical Center, San Francisco, California 94121, and the Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158
| | - Gary Cecchini
- Departments of Pharmacology and Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, the Molecular Biology Division, Veterans Affairs Medical Center, San Francisco, California 94121, and the Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158
| | - Tina M. Iverson
- Departments of Pharmacology and Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, the Molecular Biology Division, Veterans Affairs Medical Center, San Francisco, California 94121, and the Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158
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