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Ahn YO, Albertsson I, Gennis RB, Ädelroth P. Mechanism of proton transfer through the K C proton pathway in the Vibrio cholerae cbb 3 terminal oxidase. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2018; 1859:1191-1198. [PMID: 30251700 PMCID: PMC6260837 DOI: 10.1016/j.bbabio.2018.08.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 08/17/2018] [Accepted: 08/20/2018] [Indexed: 11/17/2022]
Abstract
The heme‑copper oxidases (HCuOs) are terminal components of the respiratory chain, catalyzing oxygen reduction coupled to the generation of a proton motive force. The C-family HCuOs, found in many pathogenic bacteria under low oxygen tension, utilize a single proton uptake pathway to deliver protons both for O2 reduction and for proton pumping. This pathway, called the KC-pathway, starts at Glu-49P in the accessory subunit CcoP, and connects into the catalytic subunit CcoN via the polar residues Tyr-(Y)-227, Asn (N)-293, Ser (S)-244, Tyr (Y)-321 and internal water molecules, and continues to the active site. However, although the residues are known to be functionally important, little is known about the mechanism and dynamics of proton transfer in the KC-pathway. Here, we studied variants of Y227, N293 and Y321. Our results show that in the N293L variant, proton-coupled electron transfer is slowed during single-turnover oxygen reduction, and moreover it shows a pH dependence that is not observed in wildtype. This suggests that there is a shift in the pKa of an internal proton donor into an experimentally accessible range, from >10 in wildtype to ~8.8 in N293L. Furthermore, we show that there are distinct roles for the conserved Y321 and Y227. In Y321F, proton uptake from bulk solution is greatly impaired, whereas Y227F shows wildtype-like rates and retains ~50% turnover activity. These tyrosines have evolutionary counterparts in the K-pathway of B-family HCuOs, but they do not have the same roles, indicating diversity in the proton transfer dynamics in the HCuO superfamily.
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Affiliation(s)
- Young O Ahn
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden; Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Street, Urbana, IL 61801, USA
| | - Ingrid Albertsson
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Robert B Gennis
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Street, Urbana, IL 61801, USA
| | - Pia Ädelroth
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
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Carvalheda CA, Pisliakov AV. On the role of subunit M in cytochrome cbb 3 oxidase. Biochem Biophys Res Commun 2017; 491:47-52. [PMID: 28694191 DOI: 10.1016/j.bbrc.2017.07.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 07/06/2017] [Indexed: 10/19/2022]
Abstract
Cytochrome cbb3 (or C-type) oxidases are a highly divergent group and the least studied members of the heme-copper oxidases (HCOs) superfamily. HCOs couple the reduction of oxygen at the end of the respiratory chain to the active proton translocation across the membrane, contributing to establishment of an electrochemical gradient essential for ATP synthesis. Cbb3 oxidases exhibit unique structural and functional features and have an essential role in the metabolism of many clinically relevant human pathogens. Such characteristics make them a promising therapeutic target. Three subunits, N, O and P, comprise the core cbb3 complex, with N, the catalytic subunit, being highly conserved among all members of the HCO superfamily, including the A-type (aa3, mitochondrial-like) oxidases. An additional fourth subunit containing a single transmembrane (TM) helix was present in the first crystal structure of cbb3. This TM segment was recently proposed to be part of a novel protein CcoM, which was shown to have a putative role in the complex stability and assembly. In this work, we performed large-scale all-atom molecular dynamics simulations of the CcoNOPM complex to further characterize the interactions between subunit M and the core subunits and to determine whether the presence of the fourth subunit influences the water/proton channels previously described for the core complex. The previously proposed putative CcoNOPH complex is also assessed, and the potential functional redundancy of CcoM and CcoQ is discussed.
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Affiliation(s)
- Catarina A Carvalheda
- Computational Biology, School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, United Kingdom; Physics, School of Science and Engineering, University of Dundee, Nethergate, Dundee, DD1 4HN, United Kingdom.
| | - Andrei V Pisliakov
- Computational Biology, School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, United Kingdom; Physics, School of Science and Engineering, University of Dundee, Nethergate, Dundee, DD1 4HN, United Kingdom.
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Carvalheda CA, Pisliakov AV. Insights into proton translocation in cbb 3 oxidase from MD simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:396-406. [PMID: 28259641 DOI: 10.1016/j.bbabio.2017.02.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/03/2017] [Accepted: 02/27/2017] [Indexed: 01/18/2023]
Abstract
Heme-copper oxidases are membrane protein complexes that catalyse the final step of the aerobic respiration, namely the reduction of oxygen to water. The energy released during catalysis is coupled to the active translocation of protons across the membrane, which contributes to the establishment of an electrochemical gradient that is used for ATP synthesis. The distinctive C-type (or cbb3) cytochrome c oxidases, which are mostly present in proteobacteria, exhibit a number of unique structural and functional features, including high catalytic activity at low oxygen concentrations. At the moment, the functioning mechanism of C-type oxidases, in particular the proton transfer/pumping mechanism presumably via a single proton channel, is still poorly understood. In this work we used all-atom molecular dynamics simulations and continuum electrostatics calculations to obtain atomic-level insights into the hydration and dynamics of a cbb3 oxidase. We provide the details of the water dynamics and proton transfer pathways for both the "chemical" and "pumped" protons, and show that formation of protonic connections is strongly affected by the protonation state of key residues, namely H243, E323 and H337.
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Affiliation(s)
- Catarina A Carvalheda
- Computational Biology, School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, United Kingdom; Physics, School of Sciences and Engineering, University of Dundee, Nethergate, Dundee, DD1 4HN, United Kingdom.
| | - Andrei V Pisliakov
- Computational Biology, School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, United Kingdom; Physics, School of Sciences and Engineering, University of Dundee, Nethergate, Dundee, DD1 4HN, United Kingdom.
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4
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Melin F, Xie H, Meyer T, Ahn YO, Gennis RB, Michel H, Hellwig P. The unusual redox properties of C-type oxidases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1892-1899. [PMID: 27664317 DOI: 10.1016/j.bbabio.2016.09.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 09/15/2016] [Accepted: 09/19/2016] [Indexed: 10/21/2022]
Abstract
Cytochrome cbb3 (also known as C-type) oxidases belong to the family of heme-copper terminal oxidases which couple at the end of the respiratory chain the reduction of molecular oxygen into water and the pumping of protons across the membrane. They are expressed most often at low pressure of O2 and they exhibit a low homology of sequence with the cytochrome aa3 (A-type) oxidases found in mitochondria. Their binuclear active site comprises a high-spin heme b3 associated with a CuB center. The protein also contains one low-spin heme b and 3 hemes c. We address here the redox properties of cbb3 oxidases from three organisms, Rhodobacter sphaeroides, Vibrio cholerae and Pseudomonas stutzeri by means of electrochemical and spectroscopic techniques. We show that the redox potential of the heme b3 exhibits a relatively low midpoint potential, as in related cytochrome c-dependent nitric oxide reductases. Potential implications for the coupled electron transfer and proton uptake mechanism of C-type oxidases are discussed.
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Affiliation(s)
- Frederic Melin
- Laboratoire de Bioélectrochimie et Spectroscopie, Chimie de la Matière Complexe, UMR 7140, Université de Strasbourg, 1 Rue Blaise Pascal, 67000 Strasbourg, France
| | - Hao Xie
- Max Planck Institute of Biophysics, Department of Molecular Membrane Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt am Main, Germany
| | - Thomas Meyer
- Laboratoire de Bioélectrochimie et Spectroscopie, Chimie de la Matière Complexe, UMR 7140, Université de Strasbourg, 1 Rue Blaise Pascal, 67000 Strasbourg, France
| | - Young Ok Ahn
- Department of Biochemistry, University of Illinois at Urbana Champaign, USA
| | - Robert B Gennis
- Department of Biochemistry, University of Illinois at Urbana Champaign, USA
| | - Hartmut Michel
- Max Planck Institute of Biophysics, Department of Molecular Membrane Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt am Main, Germany
| | - Petra Hellwig
- Laboratoire de Bioélectrochimie et Spectroscopie, Chimie de la Matière Complexe, UMR 7140, Université de Strasbourg, 1 Rue Blaise Pascal, 67000 Strasbourg, France.
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Ahn YO, Lee HJ, Kaluka D, Yeh SR, Rousseau DL, Ädelroth P, Gennis RB. The two transmembrane helices of CcoP are sufficient for assembly of the cbb3-type heme-copper oxygen reductase from Vibrio cholerae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1231-9. [PMID: 26116881 DOI: 10.1016/j.bbabio.2015.06.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Revised: 06/17/2015] [Accepted: 06/23/2015] [Indexed: 10/23/2022]
Abstract
The C-family (cbb3) of heme-copper oxygen reductases are proton-pumping enzymes terminating the aerobic respiratory chains of many bacteria, including a number of human pathogens. The most common form of these enzymes contains one copy each of 4 subunits encoded by the ccoNOQP operon. In the cbb3 from Rhodobacter capsulatus, the enzyme is assembled in a stepwise manner, with an essential role played by an assembly protein CcoH. Importantly, it has been proposed that a transient interaction between the transmembrane domains of CcoP and CcoH is essential for assembly. Here, we test this proposal by showing that a genetically engineered form of cbb3 from Vibrio cholerae (CcoNOQP(X)) that lacks the hydrophilic domain of CcoP, where the two heme c moieties are present, is fully assembled and stable. Single-turnover kinetics of the reaction between the fully reduced CcoNOQP(X) and O2 are essentially the same as the wild type enzyme in oxidizing the 4 remaining redox-active sites. The enzyme retains approximately 10% of the steady state oxidase activity using the artificial electron donor TMPD, but has no activity using the physiological electron donor cytochrome c4, since the docking site for this cytochrome is presumably located on the absent domain of CcoP. Residue E49 in the hydrophobic domain of CcoP is the entrance of the K(C)-channel for proton input, and the E49A mutation in the truncated enzyme further reduces the steady state activity to less than 3%. Hence, the same proton channel is used by both the wild type and truncated enzymes.
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Affiliation(s)
- Young O Ahn
- Department of Biochemistry, University of Illinois, 600 S. Mathews Street, Urbana, IL 61801, USA
| | - Hyun Ju Lee
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Daniel Kaluka
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Syun-Ru Yeh
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Denis L Rousseau
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Pia Ädelroth
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Robert B Gennis
- Department of Biochemistry, University of Illinois, 600 S. Mathews Street, Urbana, IL 61801, USA.
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Cytochrome cbb3 of Thioalkalivibrio is a Na+-pumping cytochrome oxidase. Proc Natl Acad Sci U S A 2015; 112:7695-700. [PMID: 26056262 DOI: 10.1073/pnas.1417071112] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytochrome c oxidases (Coxs) are the basic energy transducers in the respiratory chain of the majority of aerobic organisms. Coxs studied to date are redox-driven proton-pumping enzymes belonging to one of three subfamilies: A-, B-, and C-type oxidases. The C-type oxidases (cbb3 cytochromes), which are widespread among pathogenic bacteria, are the least understood. In particular, the proton-pumping machinery of these Coxs has not yet been elucidated despite the availability of X-ray structure information. Here, we report the discovery of the first (to our knowledge) sodium-pumping Cox (Scox), a cbb3 cytochrome from the extremely alkaliphilic bacterium Thioalkalivibrio versutus. This finding offers clues to the previously unknown structure of the ion-pumping channel in the C-type Coxs and provides insight into the functional properties of this enzyme.
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Arjona D, Wikström M, Ädelroth P. Nitric oxide is a potent inhibitor of the cbb(3)-type heme-copper oxidases. FEBS Lett 2015; 589:1214-8. [PMID: 25862499 DOI: 10.1016/j.febslet.2015.03.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 03/19/2015] [Accepted: 03/26/2015] [Indexed: 11/29/2022]
Abstract
C-type heme-copper oxidases terminate the respiratory chain in many pathogenic bacteria, and will encounter elevated concentrations of NO produced by the immune defense of the host. Thus, a decreased sensitivity to NO in C-type oxidases would increase the survival of these pathogens. Here we have compared the inhibitory effect of NO in C-type oxidases to that in the mitochondrial A-type. We show that O2-reduction in both the Rhodobacter sphaeroides and Vibrio cholerae C-type oxidases is strongly and reversibly inhibited by submicromolar NO, with an inhibition pattern similar to the A-type. Thus, NO tolerance in pathogens with a C-type terminal oxidase has to rely mainly on other mechanisms.
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Affiliation(s)
- Davinia Arjona
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Mårten Wikström
- Helsinki Bioenergetics Group, Institute of Biotechnology, University of Helsinki, FI-00014 Helsinki, Finland
| | - Pia Ädelroth
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
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