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Grossman AS, Gell DA, Wu DG, Carper DL, Hettich RL, Goodrich-Blair H. Bacterial hemophilin homologs and their specific type eleven secretor proteins have conserved roles in heme capture and are diversifying as a family. J Bacteriol 2024; 206:e0044423. [PMID: 38506530 DOI: 10.1128/jb.00444-23] [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: 01/05/2024] [Accepted: 02/18/2024] [Indexed: 03/21/2024] Open
Abstract
Cellular life relies on enzymes that require metals, which must be acquired from extracellular sources. Bacteria utilize surface and secreted proteins to acquire such valuable nutrients from their environment. These include the cargo proteins of the type eleven secretion system (T11SS), which have been connected to host specificity, metal homeostasis, and nutritional immunity evasion. This Sec-dependent, Gram-negative secretion system is encoded by organisms throughout the phylum Proteobacteria, including human pathogens Neisseria meningitidis, Proteus mirabilis, Acinetobacter baumannii, and Haemophilus influenzae. Experimentally verified T11SS-dependent cargo include transferrin-binding protein B (TbpB), the hemophilin homologs heme receptor protein C (HrpC), hemophilin A (HphA), the immune evasion protein factor-H binding protein (fHbp), and the host symbiosis factor nematode intestinal localization protein C (NilC). Here, we examined the specificity of T11SS systems for their cognate cargo proteins using taxonomically distributed homolog pairs of T11SS and hemophilin cargo and explored the ligand binding ability of those hemophilin cargo homologs. In vivo expression in Escherichia coli of hemophilin homologs revealed that each is secreted in a specific manner by its cognate T11SS protein. Sequence analysis and structural modeling suggest that all hemophilin homologs share an N-terminal ligand-binding domain with the same topology as the ligand-binding domains of the Haemophilus haemolyticus heme binding protein (Hpl) and HphA. We term this signature feature of this group of proteins the hemophilin ligand-binding domain. Network analysis of hemophilin homologs revealed five subclusters and representatives from four of these showed variable heme-binding activities, which, combined with sequence-structure variation, suggests that hemophilins are diversifying in function.IMPORTANCEThe secreted protein hemophilin and its homologs contribute to the survival of several bacterial symbionts within their respective host environments. Here, we compared taxonomically diverse hemophilin homologs and their paired Type 11 secretion systems (T11SS) to determine if heme binding and T11SS secretion are conserved characteristics of this family. We establish the existence of divergent hemophilin sub-families and describe structural features that contribute to distinct ligand-binding behaviors. Furthermore, we demonstrate that T11SS are specific for their cognate hemophilin family cargo proteins. Our work establishes that hemophilin homolog-T11SS pairs are diverging from each other, potentially evolving into novel ligand acquisition systems that provide competitive benefits in host niches.
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Affiliation(s)
- Alex S Grossman
- Department of Microbiology, University of Tennessee Knoxville, Knoxville, Tennessee, USA
| | - David A Gell
- School of Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Derek G Wu
- Department of Microbiology, University of Tennessee Knoxville, Knoxville, Tennessee, USA
- Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware, USA
| | - Dana L Carper
- Bioscience Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Robert L Hettich
- Bioscience Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Heidi Goodrich-Blair
- Department of Microbiology, University of Tennessee Knoxville, Knoxville, Tennessee, USA
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2
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Friedrich T, Wohlwend D, Borisov VB. Recent Advances in Structural Studies of Cytochrome bd and Its Potential Application as a Drug Target. Int J Mol Sci 2022; 23:ijms23063166. [PMID: 35328590 PMCID: PMC8951039 DOI: 10.3390/ijms23063166] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/14/2022] [Accepted: 03/14/2022] [Indexed: 02/06/2023] Open
Abstract
Cytochrome bd is a triheme copper-free terminal oxidase in membrane respiratory chains of prokaryotes. This unique molecular machine couples electron transfer from quinol to O2 with the generation of a proton motive force without proton pumping. Apart from energy conservation, the bd enzyme plays an additional key role in the microbial cell, being involved in the response to different environmental stressors. Cytochrome bd promotes virulence in a number of pathogenic species that makes it a suitable molecular drug target candidate. This review focuses on recent advances in understanding the structure of cytochrome bd and the development of its selective inhibitors.
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Affiliation(s)
- Thorsten Friedrich
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany; (T.F.); (D.W.)
| | - Daniel Wohlwend
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany; (T.F.); (D.W.)
| | - Vitaliy B. Borisov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow, Russia
- Correspondence:
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Structure of Escherichia coli cytochrome bd-II type oxidase with bound aurachin D. Nat Commun 2021; 12:6498. [PMID: 34764272 PMCID: PMC8585947 DOI: 10.1038/s41467-021-26835-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
Cytochrome bd quinol:O2 oxidoreductases are respiratory terminal oxidases so far only identified in prokaryotes, including several pathogenic bacteria. Escherichia coli contains two bd oxidases of which only the bd-I type is structurally characterized. Here, we report the structure of the Escherichia coli cytochrome bd-II type oxidase with the bound inhibitor aurachin D as obtained by electron cryo-microscopy at 3 Å resolution. The oxidase consists of subunits AppB, C and X that show an architecture similar to that of bd-I. The three heme cofactors are found in AppC, while AppB is stabilized by a structural ubiquinone-8 at the homologous positions. A fourth subunit present in bd-I is lacking in bd-II. Accordingly, heme b595 is exposed to the membrane but heme d embedded within the protein and showing an unexpectedly high redox potential is the catalytically active centre. The structure of the Q-loop is fully resolved, revealing the specific aurachin binding. Terminal bd oxidases endow bacterial pathogens with resistance to cellular stressors. The authors report the structure of E. coli bd-II type oxidase with the bound inhibitor aurachin D, providing a structural basis for the design of specifically binding antibiotics.
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Borisov VB, Siletsky SA, Paiardini A, Hoogewijs D, Forte E, Giuffrè A, Poole RK. Bacterial Oxidases of the Cytochrome bd Family: Redox Enzymes of Unique Structure, Function, and Utility As Drug Targets. Antioxid Redox Signal 2021; 34:1280-1318. [PMID: 32924537 PMCID: PMC8112716 DOI: 10.1089/ars.2020.8039] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 09/01/2020] [Accepted: 09/02/2020] [Indexed: 12/23/2022]
Abstract
Significance: Cytochrome bd is a ubiquinol:oxygen oxidoreductase of many prokaryotic respiratory chains with a unique structure and functional characteristics. Its primary role is to couple the reduction of molecular oxygen, even at submicromolar concentrations, to water with the generation of a proton motive force used for adenosine triphosphate production. Cytochrome bd is found in many bacterial pathogens and, surprisingly, in bacteria formally denoted as anaerobes. It endows bacteria with resistance to various stressors and is a potential drug target. Recent Advances: We summarize recent advances in the biochemistry, structure, and physiological functions of cytochrome bd in the light of exciting new three-dimensional structures of the oxidase. The newly discovered roles of cytochrome bd in contributing to bacterial protection against hydrogen peroxide, nitric oxide, peroxynitrite, and hydrogen sulfide are assessed. Critical Issues: Fundamental questions remain regarding the precise delineation of electron flow within this multihaem oxidase and how the extraordinarily high affinity for oxygen is accomplished, while endowing bacteria with resistance to other small ligands. Future Directions: It is clear that cytochrome bd is unique in its ability to confer resistance to toxic small molecules, a property that is significant for understanding the propensity of pathogens to possess this oxidase. Since cytochrome bd is a uniquely bacterial enzyme, future research should focus on harnessing fundamental knowledge of its structure and function to the development of novel and effective antibacterial agents.
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Affiliation(s)
- Vitaliy B. Borisov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Sergey A. Siletsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | | | - David Hoogewijs
- Department of Medicine/Physiology, University of Fribourg, Fribourg, Switzerland
| | - Elena Forte
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | | | - Robert K. Poole
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, United Kingdom
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Nikolaev A, Safarian S, Thesseling A, Wohlwend D, Friedrich T, Michel H, Kusumoto T, Sakamoto J, Melin F, Hellwig P. Electrocatalytic evidence of the diversity of the oxygen reaction in the bacterial bd oxidase from different organisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148436. [PMID: 33940039 DOI: 10.1016/j.bbabio.2021.148436] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 04/16/2021] [Accepted: 04/21/2021] [Indexed: 11/30/2022]
Abstract
Cytochrome bd oxidase is a bacterial terminal oxygen reductase that was suggested to enable adaptation to different environments and to confer resistance to stress conditions. An electrocatalytic study of the cyt bd oxidases from Escherichia coli, Corynebacterium glutamicum and Geobacillus thermodenitrificans gives evidence for a different reactivity towards oxygen. An inversion of the redox potential values of the three hemes is found when comparing the enzymes from different bacteria. This inversion can be correlated with different protonated glutamic acids as evidenced by reaction induced FTIR spectroscopy. The influence of the microenvironment of the hemes on the reactivity towards oxygen is discussed.
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Affiliation(s)
- Anton Nikolaev
- Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, Chimie de la Matière Complexe, Université de Strasbourg - CNRS 4, rue Blaise Pascal, 67081 Strasborg, France
| | - Schara Safarian
- Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | | | - Daniel Wohlwend
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Thorsten Friedrich
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Hartmut Michel
- Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Tomoichirou Kusumoto
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Fukuoka, Japan
| | - Junshi Sakamoto
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Fukuoka, Japan
| | - Frederic Melin
- Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, Chimie de la Matière Complexe, Université de Strasbourg - CNRS 4, rue Blaise Pascal, 67081 Strasborg, France.
| | - Petra Hellwig
- Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, Chimie de la Matière Complexe, Université de Strasbourg - CNRS 4, rue Blaise Pascal, 67081 Strasborg, France; USIAS, University of Strasbourg Institute for Advanced Studies, Strasbourg, France.
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6
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Petrik ID, Davydov R, Kahle M, Sandoval B, Dwaraknath S, Ädelroth P, Hoffman B, Lu Y. An Engineered Glutamate in Biosynthetic Models of Heme-Copper Oxidases Drives Complete Product Selectivity by Tuning the Hydrogen-Bonding Network. Biochemistry 2021; 60:346-355. [PMID: 33464878 PMCID: PMC7888536 DOI: 10.1021/acs.biochem.0c00852] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Efficiently carrying out the oxygen reduction reaction (ORR) is critical for many applications in biology and chemistry, such as bioenergetics and fuel cells, respectively. In biology, this reaction is carried out by large, transmembrane oxidases such as heme-copper oxidases (HCOs) and cytochrome bd oxidases. Common to these oxidases is the presence of a glutamate residue next to the active site, but its precise role in regulating the oxidase activity remains unclear. To gain insight into its role, we herein report that incorporation of glutamate next to a designed heme-copper center in two biosynthetic models of HCOs improves O2 binding affinity, facilitates protonation of reaction intermediates, and eliminates release of reactive oxygen species. High-resolution crystal structures of the models revealed extended, water-mediated hydrogen-bonding networks involving the glutamate. Electron paramagnetic resonance of the cryoreduced oxy-ferrous centers at cryogenic temperature followed by thermal annealing allowed observation of the key hydroperoxo intermediate that can be attributed to the hydrogen-bonding network. By demonstrating these important roles of glutamate in oxygen reduction biochemistry, this work offers deeper insights into its role in native oxidases, which may guide the design of more efficient artificial ORR enzymes or catalysts for applications such as fuel cells.
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Affiliation(s)
- Igor D. Petrik
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Roman Davydov
- The Department of Chemistry, Northwestern University, Evanston, Illinois 60201
| | - Maximilian Kahle
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Braddock Sandoval
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sudharsan Dwaraknath
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Pia Ädelroth
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Brian Hoffman
- The Department of Chemistry, Northwestern University, Evanston, Illinois 60201
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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Sviriaeva E, Subramanian Manimekalai MS, Grüber G, Pethe K. Features and Functional Importance of Key Residues of the Mycobacterium tuberculosis Cytochrome bd Oxidase. ACS Infect Dis 2020; 6:1697-1707. [PMID: 32379966 DOI: 10.1021/acsinfecdis.9b00449] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cytochrome bd (cyt-bd) oxygen reductases have a high affinity to oxygen and use the two electrons provided by ubiquinol or menaquinol, like in mycobacteria, to reduce oxygen to water. Although they do not pump protons from the cytoplasmic to the periplasmic side, they generate a proton motive force due to the release of protons after quinol oxidation. Here, we show that the mycobacterial cyt-bd has a number of specific features, including a 17-residue stretch (307SGVTLQGIRDLQQEYQQ323) near the Q-loop of the Mycobacterium tuberculosis subunit CydA and a 412QLVRLTVKA420 region on the periplasmic side. Site directed mutagenesis and whole-bacteria assays demonstrated that these mycobacteria-specific stretches are essential for the oxidase's function. Single amino acid substitutions around the 307SGVTLQGIRDLQQEYQQ323 stretch revealed the importance of the aromatic residue Y330 in oxygen consumption and consequently in ATP synthesis. A moderate reduction and no effect was observed for mutants F325 and Y321, respectively, while the double mutant CydAY321/F325 drastically reduced enzyme activity. In addition, single mutants of the mycobacterial cyt-bd were generated to probe the role of proposed critical residues for proton shuffling. Further data demonstrate that amino acids W64 and F18 in the CydB subunit might be important as any slight destabilization of the hydrophobic environment near them makes the enzyme inactive. Finally, the potential of the mycobacterial cyt-bd as a drug target is discussed.
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Affiliation(s)
- Ekaterina Sviriaeva
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Republic of Singapore
- Lee Kong Chian School of Medicine, 59 Nanyang Drive, Singapore 636921, Republic of Singapore
| | | | - Gerhard Grüber
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Republic of Singapore
| | - Kevin Pethe
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Republic of Singapore
- Lee Kong Chian School of Medicine, 59 Nanyang Drive, Singapore 636921, Republic of Singapore
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8
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Borisov VB, Siletsky SA. Features of Organization and Mechanism of Catalysis of Two Families of Terminal Oxidases: Heme-Copper and bd-Type. BIOCHEMISTRY (MOSCOW) 2019; 84:1390-1402. [DOI: 10.1134/s0006297919110130] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Homologous bd oxidases share the same architecture but differ in mechanism. Nat Commun 2019; 10:5138. [PMID: 31723136 PMCID: PMC6853902 DOI: 10.1038/s41467-019-13122-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/22/2019] [Indexed: 11/25/2022] Open
Abstract
Cytochrome bd oxidases are terminal reductases of bacterial and archaeal respiratory chains. The enzyme couples the oxidation of ubiquinol or menaquinol with the reduction of dioxygen to water, thus contributing to the generation of the protonmotive force. Here, we determine the structure of the Escherichia coli bd oxidase treated with the specific inhibitor aurachin by cryo-electron microscopy (cryo-EM). The major subunits CydA and CydB are related by a pseudo two fold symmetry. The heme b and d cofactors are found in CydA, while ubiquinone-8 is bound at the homologous positions in CydB to stabilize its structure. The architecture of the E. coli enzyme is highly similar to that of Geobacillus thermodenitrificans, however, the positions of heme b595 and d are interchanged, and a common oxygen channel is blocked by a fourth subunit and substituted by a more narrow, alternative channel. Thus, with the same overall fold, the homologous enzymes exhibit a different mechanism. Cytochrome bd oxidases couple quinol oxidation and the release of protons to the periplasmic side with proton uptake from the cytoplasmic side to reduce dioxygen to water and they are the terminal reductases in bacterial and archaeal respiratory chains. Here the authors present the cryo-EM structure of Escherichia coli bd oxidase and discuss mechanistic implications.
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In the respiratory chain of Escherichia coli cytochromes bd-I and bd-II are more sensitive to carbon monoxide inhibition than cytochrome bo 3. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:148088. [PMID: 31669488 DOI: 10.1016/j.bbabio.2019.148088] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 09/27/2019] [Accepted: 10/18/2019] [Indexed: 11/23/2022]
Abstract
Bacteria can not only encounter carbon monoxide (CO) in their habitats but also produce the gas endogenously. Bacterial respiratory oxidases, thus, represent possible targets for CO. Accordingly, host macrophages were proposed to produce CO and release it into the surrounding microenvironment to sense viable bacteria through a mechanism that in Escherichia (E.) coli was suggested to involve the targeting of a bd-type respiratory oxidase by CO. The aerobic respiratory chain of E. coli possesses three terminal quinol:O2-oxidoreductases: the heme-copper oxidase bo3 and two copper-lacking bd-type oxidases, bd-I and bd-II. Heme-copper and bd-type oxidases differ in the mechanism and efficiency of proton motive force generation and in resistance to oxidative and nitrosative stress, cyanide and hydrogen sulfide. Here, we investigated at varied O2 concentrations the effect of CO gas on the O2 reductase activity of the purified cytochromes bo3, bd-I and bd-II of E. coli. We found that CO, in competition with O2, reversibly inhibits the three enzymes. The inhibition constants Ki for the bo3, bd-I and bd-II oxidases are 2.4 ± 0.3, 0.04 ± 0.01 and 0.2 ± 0.1 μM CO, respectively. Thus, in E. coli, bd-type oxidases are more sensitive to CO inhibition than the heme-copper cytochrome bo3. The possible physiological consequences of this finding are discussed.
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