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Mechanistic and structural diversity between cytochrome bd isoforms of Escherichia coli. Proc Natl Acad Sci U S A 2021; 118:2114013118. [PMID: 34873041 DOI: 10.1073/pnas.2114013118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2021] [Indexed: 12/14/2022] Open
Abstract
The treatment of infectious diseases caused by multidrug-resistant pathogens is a major clinical challenge of the 21st century. The membrane-embedded respiratory cytochrome bd-type oxygen reductase is a critical survival factor utilized by pathogenic bacteria during infection, proliferation and the transition from acute to chronic states. Escherichia coli encodes for two cytochrome bd isoforms that are both involved in respiration under oxygen limited conditions. Mechanistic and structural differences between cydABX (Ecbd-I) and appCBX (Ecbd-II) operon encoded cytochrome bd variants have remained elusive in the past. Here, we demonstrate that cytochrome bd-II catalyzes oxidation of benzoquinols while possessing additional specificity for naphthoquinones. Our data show that although menaquinol-1 (MK1) is not able to directly transfer electrons onto cytochrome bd-II from E. coli, it has a stimulatory effect on its oxygen reduction rate in the presence of ubiquinol-1. We further determined cryo-EM structures of cytochrome bd-II to high resolution of 2.1 Å. Our structural insights confirm that the general architecture and substrate accessible pathways are conserved between the two bd oxidase isoforms, but two notable differences are apparent upon inspection: (i) Ecbd-II does not contain a CydH-like subunit, thereby exposing heme b 595 to the membrane environment and (ii) the AppB subunit harbors a structural demethylmenaquinone-8 molecule instead of ubiquinone-8 as found in CydB of Ecbd-I Our work completes the structural landscape of terminal respiratory oxygen reductases of E. coli and suggests that structural and functional properties of the respective oxidases are linked to quinol-pool dependent metabolic adaptations in E. coli.
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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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Murali R, Gennis RB. Functional importance of Glutamate-445 and Glutamate-99 in proton-coupled electron transfer during oxygen reduction by cytochrome bd from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:577-590. [PMID: 29719208 DOI: 10.1016/j.bbabio.2018.04.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 04/25/2018] [Accepted: 04/26/2018] [Indexed: 12/27/2022]
Abstract
The recent X-ray structure of the cytochrome bd respiratory oxygen reductase showed that two of the three heme components, heme d and heme b595, have glutamic acid as an axial ligand. No other native heme proteins are known to have glutamic acid axial ligands. In this work, site-directed mutagenesis is used to probe the roles of these glutamic acids, E445 and E99 in the E. coli enzyme. It is concluded that neither glutamate is a strong ligand to the heme Fe and they are not the major determinates of heme binding to the protein. Although very important, neither glutamate is absolutely essential for catalytic function. The close interactions between the three hemes in cyt bd result in highly cooperative properties. For example, mutation of E445, which is near heme d, has its greatest effects on the properties of heme b595 and heme b558. It is concluded that 1) O2 binds to the hydrophilic side of heme d and displaces E445; 2) E445 forms a salt bridge with R448 within the O2 binding pocket, and both residues play a role to stabilize oxygenated states of heme d during catalysis; 3) E445 and E99 are each protonated accompanying electron transfer to heme d and heme b595, respectively; 4) All protons used to generate water within the heme d active site come from the cytoplasm and are delivered through a channel that must include internal water molecules to assist proton transfer: [cytoplasm] → E107 → E99 (heme b595) → E445 (heme d) → oxygenated heme d.
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Affiliation(s)
- Ranjani Murali
- Department of Biochemistry, University of Illinois, 600 S. Mathews Street, Urbana, IL 61801, USA
| | - Robert B Gennis
- Department of Biochemistry, University of Illinois, 600 S. Mathews Street, Urbana, IL 61801, USA.
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Degli Esposti M, Rosas-Pérez T, Servín-Garcidueñas LE, Bolaños LM, Rosenblueth M, Martínez-Romero E. Molecular evolution of cytochrome bd oxidases across proteobacterial genomes. Genome Biol Evol 2015; 7:801-20. [PMID: 25688108 PMCID: PMC5322542 DOI: 10.1093/gbe/evv032] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
This work is aimed to resolve the complex molecular evolution of cytochrome bd ubiquinol oxidase, a nearly ubiquitous bacterial enzyme that is involved in redox balance and bioenergetics. Previous studies have created an unclear picture of bd oxidases phylogenesis without considering the existence of diverse types of bd oxidases. Integrated approaches of genomic and protein analysis focused on proteobacteria have generated a molecular classification of diverse types of bd oxidases, which produces a new scenario for interpreting their evolution. A duplication of the original gene cluster of bd oxidase might have occurred in the ancestors of extant α-proteobacteria of the Rhodospirillales order, such as Acidocella, from which the bd-I type of the oxidase might have diffused to other proteobacterial lineages. In contrast, the Cyanide-Insensitive Oxidase type may have differentiated into recognizable subtypes after another gene cluster duplication. These subtypes are widespread in the genomes of α-, β-, and γ-proteobacteria, with occasional instances of lateral gene transfer. In resolving the evolutionary pattern of proteobacterial bd oxidases, this work sheds new light on the basal taxa of α-proteobacteria from which the γ-proteobacterial lineage probably emerged.
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Subunit CydX of Escherichia coli cytochrome bd ubiquinol oxidase is essential for assembly and stability of the di-heme active site. FEBS Lett 2014; 588:1537-41. [PMID: 24681096 DOI: 10.1016/j.febslet.2014.03.036] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 03/08/2014] [Accepted: 03/14/2014] [Indexed: 11/23/2022]
Abstract
Cytochrome bd ubiquinol oxidase uses the electron transport from ubiquinol to oxygen to establish a proton gradient across the membrane. The enzyme complex consists of subunits CydA and B and contains two b- and one d-type hemes as cofactors. Recently, it was proposed that a third subunit named CydX is essential for the function of the complex. Here, we show that CydX is indeed a subunit of purified Escherichia coli cytochrome bd oxidase and that the small protein is needed either for the assembly or the stability of the active site di-heme center and, thus, is essential for oxidase activity.
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Miura H, Mogi T, Ano Y, Migita CT, Matsutani M, Yakushi T, Kita K, Matsushita K. Cyanide-insensitive quinol oxidase (CIO) from Gluconobacter oxydans is a unique terminal oxidase subfamily of cytochrome bd. ACTA ACUST UNITED AC 2013; 153:535-45. [DOI: 10.1093/jb/mvt019] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Al-Attar S, de Vries S. Energy transduction by respiratory metallo-enzymes: From molecular mechanism to cell physiology. Coord Chem Rev 2013. [DOI: 10.1016/j.ccr.2012.05.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Arutyunyan AM, Sakamoto J, Inadome M, Kabashima Y, Borisov VB. Optical and magneto-optical activity of cytochrome bd from Geobacillus thermodenitrificans. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:2087-94. [DOI: 10.1016/j.bbabio.2012.06.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 06/13/2012] [Accepted: 06/15/2012] [Indexed: 10/28/2022]
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Paulus A, Rossius SGH, Dijk M, de Vries S. Oxoferryl-porphyrin radical catalytic intermediate in cytochrome bd oxidases protects cells from formation of reactive oxygen species. J Biol Chem 2012; 287:8830-8. [PMID: 22287551 DOI: 10.1074/jbc.m111.333542] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The quinol-linked cytochrome bd oxidases are terminal oxidases in respiration. These oxidases harbor a low spin heme b(558) that donates electrons to a binuclear heme b(595)/heme d center. The reaction with O(2) and subsequent catalytic steps of the Escherichia coli cytochrome bd-I oxidase were investigated by means of ultra-fast freeze-quench trapping followed by EPR and UV-visible spectroscopy. After the initial binding of O(2), the O-O bond is heterolytically cleaved to yield a kinetically competent heme d oxoferryl porphyrin π-cation radical intermediate (compound I) magnetically interacting with heme b(595). Compound I accumulates to 0.75-0.85 per enzyme in agreement with its much higher rate of formation (~20,000 s(-1)) compared with its rate of decay (~1,900 s(-1)). Compound I is next converted to a short lived heme d oxoferryl intermediate (compound II) in a phase kinetically matched to the oxidation of heme b(558) before completion of the reaction. The results indicate that cytochrome bd oxidases like the heme-copper oxidases break the O-O bond in a single four-electron transfer without a peroxide intermediate. However, in cytochrome bd oxidases, the fourth electron is donated by the porphyrin moiety rather than by a nearby amino acid. The production of reactive oxygen species by the cytochrome bd oxidase was below the detection level of 1 per 1000 turnovers. We propose that the two classes of terminal oxidases have mechanistically converged to enzymes in which the O-O bond is broken in a single four-electron transfer reaction to safeguard the cell from the formation of reactive oxygen species.
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Affiliation(s)
- Angela Paulus
- Department of Biotechnology, Section Enzymology, Delft University of Technology, Delft, The Netherlands
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Borisov VB, Gennis RB, Hemp J, Verkhovsky MI. The cytochrome bd respiratory oxygen reductases. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1807:1398-413. [PMID: 21756872 PMCID: PMC3171616 DOI: 10.1016/j.bbabio.2011.06.016] [Citation(s) in RCA: 367] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 06/23/2011] [Accepted: 06/24/2011] [Indexed: 01/03/2023]
Abstract
Cytochrome bd is a respiratory quinol: O₂ oxidoreductase found in many prokaryotes, including a number of pathogens. The main bioenergetic function of the enzyme is the production of a proton motive force by the vectorial charge transfer of protons. The sequences of cytochromes bd are not homologous to those of the other respiratory oxygen reductases, i.e., the heme-copper oxygen reductases or alternative oxidases (AOX). Generally, cytochromes bd are noteworthy for their high affinity for O₂ and resistance to inhibition by cyanide. In E. coli, for example, cytochrome bd (specifically, cytochrome bd-I) is expressed under O₂-limited conditions. Among the members of the bd-family are the so-called cyanide-insensitive quinol oxidases (CIO) which often have a low content of the eponymous heme d but, instead, have heme b in place of heme d in at least a majority of the enzyme population. However, at this point, no sequence motif has been identified to distinguish cytochrome bd (with a stoichiometric complement of heme d) from an enzyme designated as CIO. Members of the bd-family can be subdivided into those which contain either a long or a short hydrophilic connection between transmembrane helices 6 and 7 in subunit I, designated as the Q-loop. However, it is not clear whether there is a functional consequence of this difference. This review summarizes current knowledge on the physiological functions, genetics, structural and catalytic properties of cytochromes bd. Included in this review are descriptions of the intermediates of the catalytic cycle, the proposed site for the reduction of O₂, evidence for a proton channel connecting this active site to the bacterial cytoplasm, and the molecular mechanism by which a membrane potential is generated.
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Affiliation(s)
- Vitaliy B Borisov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russian Federation.
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Siebers B, Zaparty M, Raddatz G, Tjaden B, Albers SV, Bell SD, Blombach F, Kletzin A, Kyrpides N, Lanz C, Plagens A, Rampp M, Rosinus A, von Jan M, Makarova KS, Klenk HP, Schuster SC, Hensel R. The complete genome sequence of Thermoproteus tenax: a physiologically versatile member of the Crenarchaeota. PLoS One 2011; 6:e24222. [PMID: 22003381 PMCID: PMC3189178 DOI: 10.1371/journal.pone.0024222] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 08/08/2011] [Indexed: 11/18/2022] Open
Abstract
Here, we report on the complete genome sequence of the hyperthermophilic Crenarchaeum Thermoproteus tenax (strain Kra1, DSM 2078T) a type strain of the crenarchaeotal order Thermoproteales. Its circular 1.84-megabase genome harbors no extrachromosomal elements and 2,051 open reading frames are identified, covering 90.6% of the complete sequence, which represents a high coding density. Derived from the gene content, T. tenax is a representative member of the Crenarchaeota. The organism is strictly anaerobic and sulfur-dependent with optimal growth at 86°C and pH 5.6. One particular feature is the great metabolic versatility, which is not accompanied by a distinct increase of genome size or information density as compared to other Crenarchaeota. T. tenax is able to grow chemolithoautotrophically (CO2/H2) as well as chemoorganoheterotrophically in presence of various organic substrates. All pathways for synthesizing the 20 proteinogenic amino acids are present. In addition, two presumably complete gene sets for NADH:quinone oxidoreductase (complex I) were identified in the genome and there is evidence that either NADH or reduced ferredoxin might serve as electron donor. Beside the typical archaeal A0A1-ATP synthase, a membrane-bound pyrophosphatase is found, which might contribute to energy conservation. Surprisingly, all genes required for dissimilatory sulfate reduction are present, which is confirmed by growth experiments. Mentionable is furthermore, the presence of two proteins (ParA family ATPase, actin-like protein) that might be involved in cell division in Thermoproteales, where the ESCRT system is absent, and of genes involved in genetic competence (DprA, ComF) that is so far unique within Archaea.
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Affiliation(s)
- Bettina Siebers
- Faculty of Chemistry, Biofilm Centre, Molecular Enzyme Technology and Biochemistry, University of Duisburg-Essen, Essen, Germany
- * E-mail: (BS); (MZ)
| | - Melanie Zaparty
- Institute for Molecular and Cellular Anatomy, University of Regensburg, Regensburg, Germany
- * E-mail: (BS); (MZ)
| | - Guenter Raddatz
- Max-Planck-Institute for Biological Cybernetics, Tübingen, Germany
| | - Britta Tjaden
- Prokaryotic RNA Biology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Steve D. Bell
- Sir William Dunn School of Pathology, Oxford University, Oxford, United Kingdom
| | - Fabian Blombach
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands
| | - Arnulf Kletzin
- Institute of Microbiology and Genetics, Technical University Darmstadt, Darmstadt, Germany
| | - Nikos Kyrpides
- DOE Joint Genome Institute, Walnut Creek, California, United States of America
| | - Christa Lanz
- Genome Centre, Max-Planck-Institute for Developmental Biology, Tuebingen, Germany
| | - André Plagens
- Prokaryotic RNA Biology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Markus Rampp
- Computer Centre Garching of the Max-Planck-Society (RZG), Max-Planck-Institute for Plasma Physics, München, Germany
| | - Andrea Rosinus
- Genome Centre, Max-Planck-Institute for Developmental Biology, Tuebingen, Germany
| | - Mathias von Jan
- DSMZ, German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Kira S. Makarova
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hans-Peter Klenk
- DSMZ, German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Stephan C. Schuster
- Center for Comparative Genomics and Bioinformatics, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Reinhard Hensel
- Prokaryotic RNA Biology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
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Bloch DA, Borisov VB, Mogi T, Verkhovsky MI. Heme/heme redox interaction and resolution of individual optical absorption spectra of the hemes in cytochrome bd from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1246-53. [PMID: 19450539 DOI: 10.1016/j.bbabio.2009.05.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 05/04/2009] [Accepted: 05/11/2009] [Indexed: 10/20/2022]
Abstract
Cytochrome bd is a terminal component of the respiratory chain of Escherichia coli catalyzing reduction of molecular oxygen to water. It contains three hemes, b(558), b(595), and d. The detailed spectroelectrochemical redox titration and numerical modeling of the data reveal significant redox interaction between the low-spin heme b(558) and high-spin heme b(595), whereas the interaction between heme d and either hemes b appears to be rather weak. However, the presence of heme d itself decreases much larger interaction between the two hemes b. Fitting the titration data with a model where redox interaction between the hemes is explicitly included makes it possible to extract individual absorption spectra of all hemes. The alpha- and beta-band reduced-minus-oxidized difference spectra agree with the data published earlier ([22] J.G. Koland, M.J. Miller, R.B. Gennis, Potentiometric analysis of the purified cytochrome d terminal oxidase complex from Escherichia coli, Biochemistry 23 (1984) 1051-1056., and [23] R.M. Lorence, J.G. Koland, R.B. Gennis, Coulometric and spectroscopic analysis of the purified cytochrome d complex of Escherichia coli: evidence for the identification of "cytochrome a(1)" as cytochrome b(595), Biochemistry 25 (1986) 2314-2321.). The Soret band spectra show lambda(max)=429.5 nm, lambda(min) approximately 413 nm (heme b(558)), lambda(max)=439 nm, lambda(min) approximately 400+/-1 nm (heme b(595)), and lambda(max)=430 nm, lambda(min)=405 nm (heme d). The spectral contribution of heme d to the complex Soret band is much smaller than those of either hemes b; the Soret/alpha (DeltaA(430):DeltaA(629)) ratio for heme d is 1.6.
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Affiliation(s)
- Dmitry A Bloch
- Helsinki Bioenergetics Group, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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