51
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Poiana F, von Ballmoos C, Gonska N, Blomberg MRA, Ädelroth P, Brzezinski P. Splitting of the O-O bond at the heme-copper catalytic site of respiratory oxidases. SCIENCE ADVANCES 2017; 3:e1700279. [PMID: 28630929 PMCID: PMC5473675 DOI: 10.1126/sciadv.1700279] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 04/20/2017] [Indexed: 05/30/2023]
Abstract
Heme-copper oxidases catalyze the four-electron reduction of O2 to H2O at a catalytic site that is composed of a heme group, a copper ion (CuB), and a tyrosine residue. Results from earlier experimental studies have shown that the O-O bond is cleaved simultaneously with electron transfer from a low-spin heme (heme a/b), forming a ferryl state (PR ; Fe4+=O2-, CuB2+-OH-). We show that with the Thermus thermophilus ba3 oxidase, at low temperature (10°C, pH 7), electron transfer from the low-spin heme b to the catalytic site is faster by a factor of ~10 (τ ≅ 11 μs) than the formation of the PR ferryl (τ ≅110 μs), which indicates that O2 is reduced before the splitting of the O-O bond. Application of density functional theory indicates that the electron acceptor at the catalytic site is a high-energy peroxy state [Fe3+-O--O-(H+)], which is formed before the PR ferryl. The rates of heme b oxidation and PR ferryl formation were more similar at pH 10, indicating that the formation of the high-energy peroxy state involves proton transfer within the catalytic site, consistent with theory. The combined experimental and theoretical data suggest a general mechanism for O2 reduction by heme-copper oxidases.
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Affiliation(s)
- Federica Poiana
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | | | - Nathalie Gonska
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Margareta R. A. Blomberg
- Department of Organic Chemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Pia Ädelroth
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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52
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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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53
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Funatogawa C, Li Y, Chen Y, McDonald W, Szundi I, Fee JA, Stout CD, Einarsdóttir Ó. Role of the Conserved Valine 236 in Access of Ligands to the Active Site of Thermus thermophilus ba3 Cytochrome Oxidase. Biochemistry 2016; 56:107-119. [DOI: 10.1021/acs.biochem.6b00590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chie Funatogawa
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Yang Li
- Department
of Molecular Biology, The Scripps Institute, MB-8, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Ying Chen
- Department
of Molecular Biology, The Scripps Institute, MB-8, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - William McDonald
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Istvan Szundi
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - James A. Fee
- Department
of Molecular Biology, The Scripps Institute, MB-8, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - C. David Stout
- Department
of Molecular Biology, The Scripps Institute, MB-8, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Ólöf Einarsdóttir
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
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54
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Biosynthetic approach to modeling and understanding metalloproteins using unnatural amino acids. Sci China Chem 2016. [DOI: 10.1007/s11426-016-0343-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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55
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Mayne CG, Arcario MJ, Mahinthichaichan P, Baylon JL, Vermaas JV, Navidpour L, Wen PC, Thangapandian S, Tajkhorshid E. The cellular membrane as a mediator for small molecule interaction with membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1858:2290-2304. [PMID: 27163493 PMCID: PMC4983535 DOI: 10.1016/j.bbamem.2016.04.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 04/26/2016] [Accepted: 04/27/2016] [Indexed: 01/05/2023]
Abstract
The cellular membrane constitutes the first element that encounters a wide variety of molecular species to which a cell might be exposed. Hosting a large number of structurally and functionally diverse proteins associated with this key metabolic compartment, the membrane not only directly controls the traffic of various molecules in and out of the cell, it also participates in such diverse and important processes as signal transduction and chemical processing of incoming molecular species. In this article, we present a number of cases where details of interaction of small molecular species such as drugs with the membrane, which are often experimentally inaccessible, have been studied using advanced molecular simulation techniques. We have selected systems in which partitioning of the small molecule with the membrane constitutes a key step for its final biological function, often binding to and interacting with a protein associated with the membrane. These examples demonstrate that membrane partitioning is not only important for the overall distribution of drugs and other small molecules into different compartments of the body, it may also play a key role in determining the efficiency and the mode of interaction of the drug with its target protein. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Christopher G Mayne
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States.
| | - Mark J Arcario
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, United States; College of Medicine, University of Illinois at Urbana-Champaign, United States.
| | - Paween Mahinthichaichan
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Department of Biochemistry, University of Illinois at Urbana-Champaign, United States.
| | - Javier L Baylon
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, United States.
| | - Josh V Vermaas
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, United States.
| | - Latifeh Navidpour
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States.
| | - Po-Chao Wen
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States.
| | - Sundarapandian Thangapandian
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Department of Biochemistry, University of Illinois at Urbana-Champaign, United States.
| | - Emad Tajkhorshid
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Department of Biochemistry, University of Illinois at Urbana-Champaign, United States; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, United States; College of Medicine, University of Illinois at Urbana-Champaign, United States.
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56
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Bhagi-Damodaran A, Petrik I, Lu Y. Using Biosynthetic Models of Heme-Copper Oxidase and Nitric Oxide Reductase in Myoglobin to Elucidate Structural Features Responsible for Enzymatic Activities. Isr J Chem 2016; 56:773-790. [PMID: 27994254 PMCID: PMC5161413 DOI: 10.1002/ijch.201600033] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In biology, a heme-Cu center in heme-copper oxidases (HCOs) is used to catalyze the four-electron reduction of oxygen to water, while a heme-nonheme diiron center in nitric oxide reductases (NORs) is employed to catalyze the two-electron reduction of nitric oxide to nitrous oxide. Although much progress has been made in biochemical and biophysical studies of HCOs and NORs, structural features responsible for similarities and differences within the two enzymatic systems remain to be understood. Here, we discuss the progress made in the design and characterization of myoglobin-based enzyme models of HCOs and NORs. In particular, we focus on use of these models to understand the structure-function relations between HCOs and NORs, including the role of nonheme metals, conserved amino acids in the active site, heme types and hydrogen-bonding network in tuning enzymatic activities and total turnovers. Insights gained from these studies are summarized and future directions are proposed.
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Affiliation(s)
| | - Igor Petrik
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL. 61801
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL. 61801
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57
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ns-μs Time-Resolved Step-Scan FTIR of ba₃ Oxidoreductase from Thermus thermophilus: Protonic Connectivity of w941-w946-w927. Int J Mol Sci 2016; 17:ijms17101657. [PMID: 27690021 PMCID: PMC5085690 DOI: 10.3390/ijms17101657] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 09/13/2016] [Accepted: 09/21/2016] [Indexed: 02/07/2023] Open
Abstract
Time-resolved step-scan FTIR spectroscopy has been employed to probe the dynamics of the ba3 oxidoreductase from Thermus thermophilus in the ns-μs time range and in the pH/pD 6–9 range. The data revealed a pH/pD sensitivity of the D372 residue and of the ring-A propionate of heme a3. Based on the observed transient changes a model in which the protonic connectivity of w941-w946-927 to the D372 and the ring-A propionate of heme a3 is described.
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58
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Yang L, Skjevik ÅA, Han Du WG, Noodleman L, Walker RC, Götz AW. Water exit pathways and proton pumping mechanism in B-type cytochrome c oxidase from molecular dynamics simulations. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1857:1594-1606. [PMID: 27317965 PMCID: PMC4995112 DOI: 10.1016/j.bbabio.2016.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 05/21/2016] [Accepted: 06/14/2016] [Indexed: 01/22/2023]
Abstract
Cytochrome c oxidase (CcO) is a vital enzyme that catalyzes the reduction of molecular oxygen to water and pumps protons across mitochondrial and bacterial membranes. While proton uptake channels as well as water exit channels have been identified for A-type CcOs, the means by which water and protons exit B-type CcOs remain unclear. In this work, we investigate potential mechanisms for proton transport above the dinuclear center (DNC) in ba3-type CcO of Thermus thermophilus. Using long-time scale, all-atom molecular dynamics (MD) simulations for several relevant protonation states, we identify a potential mechanism for proton transport that involves propionate A of the active site heme a3 and residues Asp372, His376 and Glu126(II), with residue His376 acting as the proton-loading site. The proposed proton transport process involves a rotation of residue His376 and is in line with experimental findings. We also demonstrate how the strength of the salt bridge between residues Arg225 and Asp287 depends on the protonation state and that this salt bridge is unlikely to act as a simple electrostatic gate that prevents proton backflow. We identify two water exit pathways that connect the water pool above the DNC to the outer P-side of the membrane, which can potentially also act as proton exit transport pathways. Importantly, these water exit pathways can be blocked by narrowing the entrance channel between residues Gln151(II) and Arg449/Arg450 or by obstructing the entrance through a conformational change of residue Tyr136, respectively, both of which seem to be affected by protonation of residue His376.
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Affiliation(s)
- Longhua Yang
- Department of Chemistry, Nanchang University, 999 Xuefudadao, Nanchang, Jiangxi 330031, China; San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Drive MC0505, La Jolla, CA 92093, USA
| | - Åge A Skjevik
- San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Drive MC0505, La Jolla, CA 92093, USA; Department of Biomedicine, University of Bergen, N-5009 Bergen, Norway
| | - Wen-Ge Han Du
- Department of Integrative Structural and Computational Biology, GAC1118, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Louis Noodleman
- Department of Integrative Structural and Computational Biology, GAC1118, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Ross C Walker
- San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Drive MC0505, La Jolla, CA 92093, USA; Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
| | - Andreas W Götz
- San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Drive MC0505, La Jolla, CA 92093, USA.
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59
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Abstract
Measurements of voltage changes in response to charge separation within membrane proteins can offer fundamental information on spectroscopically "invisible" steps. For example, results from studies of voltage changes associated with electron and proton transfer in cytochrome c oxidase could, in principle, be used to discriminate between different theoretical models describing the molecular mechanism of proton pumping. Earlier analyses of data from these measurements have been based on macroscopic considerations that may not allow for exploring the actual molecular mechanisms. Here, we have used a coarse-grained model describing the relation between observed voltage changes and specific charge-transfer reactions, which includes an explicit description of the membrane, the electrolytes, and the electrodes. The results from these calculations offer mechanistic insights at the molecular level. Our main conclusion is that previously assumed mechanistic evidence that was based on electrogenic measurements is not unique. However, the ability of our calculations to obtain reliable voltage changes means that we have a tool that can be used to describe a wide range of electrogenic charge transfers in channels and transporters, by combining voltage measurements with other experiments and simulations to analyze new mechanistic proposals.
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60
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Crow A, Matsuda Y, Arata H, Oubrie A. Structure of the Membrane-intrinsic Nitric Oxide Reductase from Roseobacter denitrificans. Biochemistry 2016; 55:3198-203. [DOI: 10.1021/acs.biochem.6b00332] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Allister Crow
- Department
of Pathology, University of Cambridge, Cambridge, U.K
| | - Yuji Matsuda
- Department
of Biology, Kyushu University, Fukuoka, Japan
| | - Hiroyuki Arata
- Department
of Biology, Kyushu University, Fukuoka, Japan
| | - Arthur Oubrie
- Lead Pharma, Pivot Park, 5349AC Oss, The Netherlands
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61
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Cassano JA, Choi SK, McDonald W, Szundi I, Villa Gawboy TR, Gennis RB, Einarsdóttir Ó. The CO Photodissociation and Recombination Dynamics of the W172Y/F282T Ligand Channel Mutant of Rhodobacter sphaeroides aa3 Cytochrome c Oxidase. Photochem Photobiol 2016; 92:410-9. [PMID: 27029379 DOI: 10.1111/php.12587] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 02/25/2016] [Indexed: 12/26/2022]
Abstract
In the ligand channel of the cytochrome c oxidase from Rhodobacter sphaeroides (Rs aa3 ) W172 and F282 have been proposed to generate a constriction that may slow ligand access to and from the active site. To explore this issue, the tryptophan and phenylalanine residues in Rs aa3 were mutated to the less bulky tyrosine and threonine residues, respectively, which occupy these sites in Thermus thermophilus (Tt) ba3 cytochrome oxidase. The CO photolysis and recombination dynamics of the reduced wild-type Rs aa3 and the W172Y/F282T mutant were investigated using time-resolved optical absorption spectroscopy. The spectral changes associated with the multiple processes are attributed to different conformers. The major CO recombination process (44 μs) in the W172Y/F282T mutant is ~500 times faster than the predominant CO recombination process in the wild-type enzyme (~23 ms). Classical dynamic simulations of the wild-type enzyme and double mutant showed significant structural changes at the active site in the mutant, including movement of the heme a3 ring-D propionate toward CuB and reduced binuclear center cavity volume. These structural changes effectively close the ligand exit pathway from the binuclear center, providing a basis for the faster CO recombination in the double mutant.
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Affiliation(s)
- Jennifer A Cassano
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA
| | - Sylvia K Choi
- Center for Biophysics and Computational Biology, Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL
| | - William McDonald
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA
| | - Istvan Szundi
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA
| | - Terra R Villa Gawboy
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA
| | - Robert B Gennis
- Center for Biophysics and Computational Biology, Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL
| | - Ólöf Einarsdóttir
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA
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62
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Han Du WG, Götz AW, Yang L, Walker RC, Noodleman L. A broken-symmetry density functional study of structures, energies, and protonation states along the catalytic O-O bond cleavage pathway in ba3 cytochrome c oxidase from Thermus thermophilus. Phys Chem Chem Phys 2016; 18:21162-71. [PMID: 27094074 DOI: 10.1039/c6cp00349d] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Broken-symmetry density functional calculations have been performed on the [Fea3, CuB] dinuclear center (DNC) of ba3 cytochrome c oxidase from Thermus thermophilus in the states of [Fea3(3+)-(HO2)(-)-CuB(2+), Tyr237(-)] and [Fea3(4+)[double bond, length as m-dash]O(2-), OH(-)-CuB(2+), Tyr237˙], using both PW91-D3 and OLYP-D3 functionals. Tyr237 is a special tyrosine cross-linked to His233, a ligand of CuB. The calculations have shown that the DNC in these states strongly favors the protonation of His376, which is above propionate-A, but not of the carboxylate group of propionate-A. The energies of the structures obtained by constrained geometry optimizations along the O-O bond cleavage pathway between [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] and [Fea3(4+)[double bond, length as m-dash]O(2-)HO(-)-CuB(2+), Tyr237˙] have also been calculated. The transition of [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] → [Fea3(4+)[double bond, length as m-dash]O(2-)HO(-)-CuB(2+), Tyr237˙] shows a very small barrier, which is less than 3.0/2.0 kcal mol(-1) in PW91-D3/OLYP-D3 calculations. The protonation state of His376 does not affect this O-O cleavage barrier. The rate limiting step of the transition from state A (in which O2 binds to Fea3(2+)) to state PM ([Fea3(4+)[double bond, length as m-dash]O(2-), OH(-)-CuB(2+), Tyr237˙], where the O-O bond is cleaved) in the catalytic cycle is, therefore, the proton transfer originating from Tyr237 to O-O to form the hydroperoxo [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] state. The importance of His376 in proton uptake and the function of propionate-A/neutral-Asp372 as a gate to prevent the proton from back-flowing to the DNC are also shown.
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Affiliation(s)
- Wen-Ge Han Du
- Department of Integrative Structural and Computational Biology, GAC1118, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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63
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Mahinthichaichan P, Gennis RB, Tajkhorshid E. All the O2 Consumed by Thermus thermophilus Cytochrome ba3 Is Delivered to the Active Site through a Long, Open Hydrophobic Tunnel with Entrances within the Lipid Bilayer. Biochemistry 2016; 55:1265-78. [PMID: 26845082 DOI: 10.1021/acs.biochem.5b01255] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Cytochrome ba3 is a proton-pumping heme-copper oxygen reductase from the extreme thermophile Thermus thermophilus. Despite the fact that the enzyme's active site is buried deep within the protein, the apparent second order rate constant for the initial binding of O2 to the active-site heme has been experimentally found to be 10(9) M(-1) s(-1) at 298 K, at or near the diffusion limit, and 2 orders of magnitude faster than for O2 binding to myoglobin. To provide quantitative and microscopic descriptions of the O2 delivery pathway and mechanism in cytochrome ba3, extensive molecular dynamics simulations of the enzyme in its membrane-embedded form have been performed, including different protocols of explicit ligand sampling (flooding) simulations with O2, implicit ligand sampling analysis, and in silico mutagenesis. The results show that O2 diffuses to the active site exclusively via a Y-shaped hydrophobic tunnel with two 25-Å long membrane-accessible branches that coincide with the pathway previously suggested by the crystallographically identified xenon binding sites. The two entrances of the bifurcated tunnel of cytochrome ba3 are located within the lipid bilayer, where O2 is preferentially partitioned from the aqueous phase. The largest barrier to O2 migration within the tunnel is estimated to be only 1.5 kcal/mol, allowing O2 to reach the enzyme active site virtually impeded by one-dimensional diffusion once it reaches a tunnel entrance at the protein surface. Unlike other O2-utilizing proteins, the tunnel is "open" with no transient barriers observed due to protein dynamics. This unique low-barrier passage through the protein ensures that O2 transit through the protein is never rate-limiting.
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Affiliation(s)
- Paween Mahinthichaichan
- Department of Biochemistry, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Robert B Gennis
- Department of Biochemistry, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- Department of Biochemistry, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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64
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Khalfaoui-Hassani B, Verissimo AF, Shroff NP, Ekici S, Trasnea PI, Utz M, Koch HG, Daldal F. Biogenesis of Cytochrome c Complexes: From Insertion of Redox Cofactors to Assembly of Different Subunits. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2016. [DOI: 10.1007/978-94-017-7481-9_27] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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65
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Lyons JA, Hilbers F, Caffrey M. Structure and Function of Bacterial Cytochrome c Oxidases. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2016. [DOI: 10.1007/978-94-017-7481-9_16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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66
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Xu N, Abucayon EG, Powell DR, Richter-Addo GB. A bridged di-iron porphyrin hyponitrite complex as a model for biological N2O production from hyponitrite. Nitric Oxide 2015; 52:16-20. [PMID: 26529479 DOI: 10.1016/j.niox.2015.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 10/20/2015] [Accepted: 10/27/2015] [Indexed: 11/30/2022]
Abstract
Heme-hyponitrites are intermediates that form at the bimetallic active sites of bacterial nitric oxide reductases. To probe a possible effect of the Fe-Fe distance on hyponitrite stability, we prepared a bridged bis-porphyrin Fe-hyponitrite compound, namely [(OEP-CH2)Fe]2(μ2,η(1),η(1)-ONNO). Its υNO of 992 cm(-1) (υ15NO of 976 cm(-1)) is close to the υNO of 983 cm(-1) reported previously by us for the crystallographically characterized [(OEP)Fe]2(μ2,η(1),η(1)-ONNO) compound. The bridged bis-porphyrin Fe-hyponitrite complex is unstable with respect to N2O production, supporting the role of the bis-Fe porphyrin system in hyponitrite conversion to N2O. The preparation and crystallographic determination of the bridging sulfato derivative is also reported.
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Affiliation(s)
- Nan Xu
- Division of Mathematics and Natural Sciences, Penn State Altoona, 3000 Ivyside Park, Altoona, PA 16601, USA; Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK 73019, USA.
| | - Erwin G Abucayon
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK 73019, USA
| | - Douglas R Powell
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK 73019, USA
| | - George B Richter-Addo
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK 73019, USA.
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67
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The cytochrome ba3 oxidase from Thermus thermophilus does not generate a tryptophan radical during turnover: Implications for the mechanism of proton pumping. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1093-100. [DOI: 10.1016/j.bbabio.2015.05.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 04/26/2015] [Accepted: 05/15/2015] [Indexed: 11/30/2022]
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68
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Loop recognition and copper-mediated disulfide reduction underpin metal site assembly of CuA in human cytochrome oxidase. Proc Natl Acad Sci U S A 2015; 112:11771-6. [PMID: 26351686 DOI: 10.1073/pnas.1505056112] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Maturation of cytochrome oxidases is a complex process requiring assembly of several subunits and adequate uptake of the metal cofactors. Two orthologous Sco proteins (Sco1 and Sco2) are essential for the correct assembly of the dicopper CuA site in the human oxidase, but their function is not fully understood. Here, we report an in vitro biochemical study that shows that Sco1 is a metallochaperone that selectively transfers Cu(I) ions based on loop recognition, whereas Sco2 is a copper-dependent thiol reductase of the cysteine ligands in the oxidase. Copper binding to Sco2 is essential to elicit its redox function and as a guardian of the reduced state of its own cysteine residues in the oxidizing environment of the mitochondrial intermembrane space (IMS). These results provide a detailed molecular mechanism for CuA assembly, suggesting that copper and redox homeostasis are intimately linked in the mitochondrion.
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69
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Han Du WG, Noodleman L. Broken Symmetry DFT Calculations/Analysis for Oxidized and Reduced Dinuclear Center in Cytochrome c Oxidase: Relating Structures, Protonation States, Energies, and Mössbauer Properties in ba3 Thermus thermophilus. Inorg Chem 2015; 54:7272-90. [PMID: 26192749 PMCID: PMC4525772 DOI: 10.1021/acs.inorgchem.5b00700] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Indexed: 12/22/2022]
Abstract
The Fea3(3+)···CuB(2+) dinuclear center (DNC) structure of the as-isolated oxidized ba3 cytochrome c oxidase (CcO) from Thermus thermophilus (Tt) is still not fully understood. When the proteins are initially crystallized in the oxidized state, they typically become radiolyticly reduced through X-ray irradiation. Several X-ray crystal structures of reduced ba3 CcO from Tt are available. However, depending on whether the crystals were prepared in a lipidic cubic phase environment or in detergent micelles, and whether the CcO's were chemically or radiolyticly reduced, the X-ray diffraction analysis of the crystals showed different Fea3(2+)···CuB(+) DNC structures. On the other hand, Mössbauer spectroscopic experiments on reduced and oxidized ba3 CcOs from Tt (Zimmermann et al., Proc. Natl. Acad. Sci. USA 1988, 85, 5779-5783) revealed multiple (57)Fea3(2+) and (57)Fea3(3+) components. Moreover, one of the (57)Fea3(3+) components observed at 4.2 K transformed from a proposed "low-spin" state to a different high-spin species when the temperature was increased above 190 K, whereas the other high-spin (57)Fea3(3+) component remained unchanged. In the current Article, in order to understand the heterogeneities of the DNC in both Mössbauer spectra and X-ray crystal structures, the spin crossover of one of the (57)Fea3(3+) components, and how the coordination and spin states of the Fea3(3+/2+) and Cu(2+/1+) sites relate to the heterogeneity of the DNC structures, we have applied density functional OLYP calculations to the DNC clusters established based on the different X-ray crystal structures of ba3 CcO from Tt. As a result, specific oxidized and reduced DNC structures related to the observed Mössbauer spectra and to spectral changes with temperature have been proposed. Our calculations also show that, in certain intermediate states, the His233 and His283 ligand side chains may dissociate from the CuB(+) site, and they may become potential proton loading sites during the catalytic cycle.
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Affiliation(s)
- Wen-Ge Han Du
- Department of Integrative Structural and Computational
Biology, CB213, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Louis Noodleman
- Department of Integrative Structural and Computational
Biology, CB213, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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70
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Proton transfer in the K-channel analog of B-type Cytochrome c oxidase from Thermus thermophilus. Biophys J 2015; 107:2177-84. [PMID: 25418102 DOI: 10.1016/j.bpj.2014.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/03/2014] [Accepted: 09/11/2014] [Indexed: 01/08/2023] Open
Abstract
A key enzyme in aerobic metabolism is cytochrome c oxidase (CcO), which catalyzes the reduction of molecular oxygen to water in the mitochondrial and bacterial membranes. Substrate electrons and protons are taken up from different sides of the membrane and protons are pumped across the membrane, thereby generating an electrochemical gradient. The well-studied A-type CcO uses two different entry channels for protons: the D-channel for all pumped and two consumed protons, and the K-channel for the other two consumed protons. In contrast, the B-type CcO uses only a single proton input channel for all consumed and pumped protons. It has the same location as the A-type K-channel (and thus is named the K-channel analog) without sharing any significant sequence homology. In this study, we performed molecular-dynamics simulations and electrostatic calculations to characterize the K-channel analog in terms of its energetic requirements and functionalities. The function of Glu-15B as a proton sink at the channel entrance is demonstrated by its rotational movement out of the channel when it is deprotonated and by its high pKA value when it points inside the channel. Tyr-244 in the middle of the channel is identified as the valve that ensures unidirectional proton transfer, as it moves inside the hydrogen-bond gap of the K-channel analog only while being deprotonated. The electrostatic energy landscape was calculated for all proton-transfer steps in the K-channel analog, which functions via proton-hole transfer. Overall, the K-channel analog has a very stable geometry without large energy barriers.
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71
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Al-Attar S, de Vries S. An electrogenic nitric oxide reductase. FEBS Lett 2015; 589:2050-7. [PMID: 26149211 DOI: 10.1016/j.febslet.2015.06.033] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/24/2015] [Accepted: 06/24/2015] [Indexed: 10/23/2022]
Abstract
Nitric oxide reductases (Nors) are members of the heme-copper oxidase superfamily that reduce nitric oxide (NO) to nitrous oxide (N₂O). In contrast to the proton-pumping cytochrome oxidases, Nors studied so far have neither been implicated in proton pumping nor have they been experimentally established as electrogenic. The copper-A-dependent Nor from Bacillus azotoformans uses cytochrome c₅₅₁ as electron donor but lacks menaquinol activity, in contrast to our earlier report (Suharti et al., 2001). Employing reduced phenazine ethosulfate (PESH) as electron donor, the main NO reduction pathway catalyzed by Cu(A)Nor reconstituted in liposomes involves transmembrane cycling of the PES radical. We show that Cu(A)Nor reconstituted in liposomes generates a proton electrochemical gradient across the membrane similar in magnitude to cytochrome aa₃, highlighting that bacilli using Cu(A)Nor can exploit NO reduction for increased cellular ATP production compared to organisms using cNor.
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Affiliation(s)
- Sinan Al-Attar
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, The Netherlands
| | - Simon de Vries
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, The Netherlands.
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72
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Mutation of a single residue in the ba3 oxidase specifically impairs protonation of the pump site. Proc Natl Acad Sci U S A 2015; 112:3397-402. [PMID: 25733886 DOI: 10.1073/pnas.1422434112] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The ba3-type cytochrome c oxidase from Thermus thermophilus is a membrane-bound protein complex that couples electron transfer to O2 to proton translocation across the membrane. To elucidate the mechanism of the redox-driven proton pumping, we investigated the kinetics of electron and proton transfer in a structural variant of the ba3 oxidase where a putative "pump site" was modified by replacement of Asp372 by Ile. In this structural variant, proton pumping was uncoupled from internal electron transfer and O2 reduction. The results from our studies show that proton uptake to the pump site (time constant ∼65 μs in the wild-type cytochrome c oxidase) was impaired in the Asp372Ile variant. Furthermore, a reaction step that in the wild-type cytochrome c oxidase is linked to simultaneous proton uptake and release with a time constant of ∼1.2 ms was slowed to ∼8.4 ms, and in Asp372Ile was only associated with proton uptake to the catalytic site. These data identify reaction steps that are associated with protonation and deprotonation of the pump site, and point to the area around Asp372 as the location of this site in the ba3 cytochrome c oxidase.
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73
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Ducluzeau AL, Schoepp-Cothenet B, van Lis R, Baymann F, Russell MJ, Nitschke W. The evolution of respiratory O2/NO reductases: an out-of-the-phylogenetic-box perspective. J R Soc Interface 2015; 11:20140196. [PMID: 24968694 DOI: 10.1098/rsif.2014.0196] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Complex life on our planet crucially depends on strong redox disequilibria afforded by the almost ubiquitous presence of highly oxidizing molecular oxygen. However, the history of O2-levels in the atmosphere is complex and prior to the Great Oxidation Event some 2.3 billion years ago, the amount of O2 in the biosphere is considered to have been extremely low as compared with present-day values. Therefore the evolutionary histories of life and of O2-levels are likely intricately intertwined. The obvious biological proxy for inferring the impact of changing O2-levels on life is the evolutionary history of the enzyme allowing organisms to tap into the redox power of molecular oxygen, i.e. the bioenergetic O2 reductases, alias the cytochrome and quinol oxidases. Consequently, molecular phylogenies reconstructed for this enzyme superfamily have been exploited over the last two decades in attempts to elucidate the interlocking between O2 levels in the environment and the evolution of respiratory bioenergetic processes. Although based on strictly identical datasets, these phylogenetic approaches have led to diametrically opposite scenarios with respect to the history of both the enzyme superfamily and molecular oxygen on the Earth. In an effort to overcome the deadlock of molecular phylogeny, we here review presently available structural, functional, palaeogeochemical and thermodynamic information pertinent to the evolution of the superfamily (which notably also encompasses the subfamily of nitric oxide reductases). The scenario which, in our eyes, most closely fits the ensemble of these non-phylogenetic data, sees the low O2-affinity SoxM- (or A-) type enzymes as the most recent evolutionary innovation and the high-affinity O2 reductases (SoxB or B and cbb3 or C) as arising independently from NO-reducing precursor enzymes.
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Affiliation(s)
- Anne-Lise Ducluzeau
- Beadle Center, University of Nebraska-Lincoln, 1901 Vine Street, Lincoln, NE 68588-0660, USA
| | - Barbara Schoepp-Cothenet
- Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/AMU, FR3479, Marseille Cedex 20 13402, France
| | - Robert van Lis
- Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/AMU, FR3479, Marseille Cedex 20 13402, France
| | - Frauke Baymann
- Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/AMU, FR3479, Marseille Cedex 20 13402, France
| | - Michael J Russell
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA
| | - Wolfgang Nitschke
- Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/AMU, FR3479, Marseille Cedex 20 13402, France
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74
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Wikström M, Sharma V, Kaila VRI, Hosler JP, Hummer G. New Perspectives on Proton Pumping in Cellular Respiration. Chem Rev 2015; 115:2196-221. [DOI: 10.1021/cr500448t] [Citation(s) in RCA: 183] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mårten Wikström
- Institute
of Biotechnology, University of Helsinki, Biocenter 3 (Viikinkaari 1), PB
65, Helsinki 00014, Finland
| | - Vivek Sharma
- Department
of Physics, Tampere University of Technology, Korkeakoulunkatu 3, Tampere 33720, Finland
| | - Ville R. I. Kaila
- Department
Chemie, Technische Universität München, Lichtenbergstraße 4, D-85748 Garching, Germany
| | - Jonathan P. Hosler
- Department
of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi 39216, United States
| | - Gerhard Hummer
- Department
of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße
3, 60438 Frankfurt
am Main, Germany
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75
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Koutsoupakis C, Soulimane T, Varotsis C. Photobiochemical production of carbon monoxide by Thermus thermophilus ba3 -cytochrome c oxidase. Chemistry 2015; 21:4958-61. [PMID: 25689606 DOI: 10.1002/chem.201406239] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Indexed: 11/08/2022]
Abstract
We report the photobiochemical production of carbon monoxide by a terminal ba3 -cytochrome c oxidase from T. thermophilus HB8. FTIR and time-resolved step-scan FTIR spectroscopies were combined to probe this process and also monitor the concomitant binding of the produced gas to other intact ba3 molecules forming the ba3 -CO complex. The activation of this mechanism by ba3 -oxidase under visible excitation raises the question as to whether such a mechanism is physiologically relevant to the extreme environment in which it operates.
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Affiliation(s)
- Constantinos Koutsoupakis
- Department of Environmental Science and Technology, Cyprus University of Technology, P.O. Box 50329, 3603 Lemesos (Cyprus)
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76
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Affiliation(s)
- Shinya Yoshikawa
- Picobiology Institute, Graduate
School of Life Science, University of Hyogo, Kamigohri Akoh Hyogo, 678-1297, Japan
| | - Atsuhiro Shimada
- Picobiology Institute, Graduate
School of Life Science, University of Hyogo, Kamigohri Akoh Hyogo, 678-1297, Japan
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77
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Nicolaides A, Soulimane T, Varotsis C. Detection of functional hydrogen-bonded water molecules with protonated/deprotonated key carboxyl side chains in the respiratory enzyme ba3-oxidoreductase. Phys Chem Chem Phys 2015; 17:8113-9. [DOI: 10.1039/c5cp00043b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work we report FTIR data on the detection of functional hydrogen-bonded water molecules with protonated/deprotonated key carboxyl side chains in the respiratory enzyme ba3-oxidoreductase.
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Affiliation(s)
- Antonis Nicolaides
- Department of Environmental Science and Technology
- Cyprus University of Technology
- 3603 Lemesos
- Cyprus
| | - Tewfik Soulimane
- Chemical and Environmental Science Department and Materials & Surface Science Institute
- University of Limerick
- Limerick
- Ireland
| | - Constantinos Varotsis
- Department of Environmental Science and Technology
- Cyprus University of Technology
- 3603 Lemesos
- Cyprus
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78
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79
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Ohta T, Soulimane T, Kitagawa T, Varotsis C. Nitric oxide activation by caa3 oxidoreductase from Thermus thermophilus. Phys Chem Chem Phys 2015; 17:10894-8. [DOI: 10.1039/c5cp01013f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present UV-Raman evidence for the formation of the hyponitrite (HO–NN–O−) species in the binuclear heme a3 Fe–CuB center (νN–N = 1330 cm−1) of caa3 heme-copper oxidoreductase from Thermus thermophilus.
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Affiliation(s)
- Takehiro Ohta
- Graduate School of Life Science
- University of Hyogo
- Hyogo 678-1297
- Japan
| | - Tewfik Soulimane
- Chemical & Environmental Sciences Department and Materials & Surface Science Institute
- University of Limerick
- Limerick
- Ireland
| | - Teizo Kitagawa
- Graduate School of Life Science
- University of Hyogo
- Hyogo 678-1297
- Japan
| | - Constantinos Varotsis
- Cyprus University of Technology
- Department of Environmental Science and Technology
- 3603 Lemesos
- Cyprus
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80
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Loullis A, Noor MR, Soulimane T, Pinakoulaki E. The structure of a ferrous heme-nitro species in the binuclear heme a3/CuB center of ba3-cytochrome c oxidase as determined by resonance Raman spectroscopy. Chem Commun (Camb) 2014; 51:286-9. [PMID: 25406996 DOI: 10.1039/c4cc08019j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Members of the cytochrome c oxidase family exhibit nitrite reductase activity. In this work, we have characterized a ferrous heme a3-nitro species in ba3-oxidase by resonance Raman spectroscopy. This provides the first evidence for the structure of a nitrite-bound species in the binuclear heme/copper center of cytochrome c oxidases.
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Affiliation(s)
- Andreas Loullis
- Department of Chemistry, University of Cyprus, PO Box 20537, 1678, Nicosia, Cyprus.
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81
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Pastorino L, Dellacasa E, Noor MR, Soulimane T, Bianchini P, D'Autilia F, Antipov A, Diaspro A, Tofail SAM, Ruggiero C. Multilayered polyelectrolyte microcapsules: interaction with the enzyme cytochrome C oxidase. PLoS One 2014; 9:e112192. [PMID: 25372607 PMCID: PMC4221607 DOI: 10.1371/journal.pone.0112192] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 10/13/2014] [Indexed: 02/01/2023] Open
Abstract
Cell-sized polyelectrolyte capsules functionalized with a redox-driven proton pump protein were assembled for the first time. The interaction of polyelectrolyte microcapsules, fabricated by electrostatic layer-by-layer assembly, with cytochrome c oxidase molecules was investigated. We found that the cytochrome c oxidase retained its functionality, that the functionalized microcapsules interacting with cytochrome c oxidase were permeable and that the permeability characteristics of the microcapsule shell depend on the shell components. This work provides a significant input towards the fabrication of an integrated device made of biological components and based on specific biomolecular functions and properties.
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Affiliation(s)
- Laura Pastorino
- Department of Informatics, Bioengineering, Robotics and Systems Engineering, University of Genova, Genova, Italy
| | - Elena Dellacasa
- Department of Informatics, Bioengineering, Robotics and Systems Engineering, University of Genova, Genova, Italy
| | - Mohamed R. Noor
- Department of Chemical and Environmental Sciences, University of Limerick, Limerick, Ireland
- Materials and Surface Science Institute, University of Limerick, Limerick, Ireland
| | - Tewfik Soulimane
- Department of Chemical and Environmental Sciences, University of Limerick, Limerick, Ireland
- Materials and Surface Science Institute, University of Limerick, Limerick, Ireland
| | | | | | | | | | - Syed A. M. Tofail
- Materials and Surface Science Institute, University of Limerick, Limerick, Ireland
| | - Carmelina Ruggiero
- Department of Informatics, Bioengineering, Robotics and Systems Engineering, University of Genova, Genova, Italy
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82
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Umadevi P, Senthilkumar L. Influence of metal ions (Zn2+, Cu2+, Ca2+, Mg2+and Na+) on the water coordinated neutral and zwitterionicl-histidine dimer. RSC Adv 2014. [DOI: 10.1039/c4ra08155b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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83
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Time-resolved infrared spectroscopic studies of ligand dynamics in the active site from cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:79-85. [PMID: 25117435 DOI: 10.1016/j.bbabio.2014.07.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 07/29/2014] [Indexed: 10/24/2022]
Abstract
The catalytic site of heme-copper oxidases encompasses two close-lying ligand binding sites: the heme, where oxygen is bound and reduced and the CuB atom, which acts as ligand entry and release port. Diatomic gaseous ligands with a dipole moment, such as the signaling molecules carbon monoxide (CO) and nitric oxide (NO), carry clear infrared spectroscopic signatures in the different states that allow characterization of the dynamics of ligand transfer within, into and out of the active site using time-resolved infrared spectroscopy. We review the nature and diversity of these processes that have in particular been characterized with CO as ligand and which take place on time scales ranging from femtoseconds to milliseconds. These studies have advanced our understanding of the functional ligand pathways and reactivity in enzymes and more globally represent intriguing model systems for mechanisms of ligand motion in a confined protein environment. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
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84
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Meyer T, Melin F, Xie H, von der Hocht I, Choi SK, Noor MR, Michel H, Gennis RB, Soulimane T, Hellwig P. Evidence for distinct electron transfer processes in terminal oxidases from different origin by means of protein film voltammetry. J Am Chem Soc 2014; 136:10854-7. [PMID: 25054669 PMCID: PMC4132979 DOI: 10.1021/ja505126v] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
![]()
Cytochrome aa3 from Paracoccus denitrificans and cytochrome ba3 from Thermus thermophilus, two distinct members of the
heme–copper oxidase superfamily,
were immobilized on electrodes modified with gold nanoparticles. This
procedure allowed us to achieve direct electron transfer between the
enzyme and the gold nanoparticles and to obtain evidence for different
electrocatalytic properties of the two enzymes. The pH dependence
and thermostability reveal that the enzymes are highly adapted to
their native environments. These results suggest that evolution resulted
in different solutions to the common problem of electron transfer
to oxygen.
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Affiliation(s)
- Thomas Meyer
- Chimie de la Matière Complexe UMR 7140, Laboratoire de Bioélectrochimie et Spectroscopie, CNRS-Université de Strasbourg , 1 rue Blaise Pascal, 67070 Strasbourg, France
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85
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McDonald W, Funatogawa C, Li Y, Chen Y, Szundi I, Fee JA, Stout CD, Einarsdóttir O. Conserved glycine 232 in the ligand channel of ba3 cytochrome oxidase from Thermus thermophilus. Biochemistry 2014; 53:4467-75. [PMID: 24937405 PMCID: PMC4216187 DOI: 10.1021/bi500289h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Knowing how the protein environment modulates ligand pathways and redox centers in the respiratory heme-copper oxidases is fundamental for understanding the relationship between the structure and function of these enzymes. In this study, we investigated the reactions of O2 and NO with the fully reduced G232V mutant of ba3 cytochrome c oxidase from Thermus thermophilus (Tt ba3) in which a conserved glycine residue in the O2 channel of the enzyme was replaced with a bulkier valine residue. Previous studies of the homologous mutant of Rhodobacter sphaeroides aa3 cytochrome c oxidase suggested that the valine completely blocked the access of O2 to the active site [Salomonsson, L., et al. (2004) Proc. Natl. Acad. Sci. U.S.A. 101, 11617-11621]. Using photolabile O2 and NO carriers, we find by using time-resolved optical absorption spectroscopy that the rates of O2 and NO binding are not significantly affected in the Tt ba3 G232V mutant. Classical molecular dynamics simulations of diffusion of O2 to the active site in the wild-type enzyme and G232V mutant show that the insertion of the larger valine residue in place of the glycine appears to open up other O2 and NO exit/entrance pathways that allow these ligands unhindered access to the active site, thus compensating for the larger valine residue.
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Affiliation(s)
- William McDonald
- Department of Chemistry and Biochemistry, University of California , Santa Cruz, California 95064, United States
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86
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Noodleman L, Han Du WG, Fee J, Götz AW, Walker RC. Linking chemical electron-proton transfer to proton pumping in cytochrome c oxidase: broken-symmetry DFT exploration of intermediates along the catalytic reaction pathway of the iron-copper dinuclear complex. Inorg Chem 2014; 53:6458-72. [PMID: 24960612 PMCID: PMC4095914 DOI: 10.1021/ic500363h] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Indexed: 12/23/2022]
Abstract
After a summary of the problem of coupling electron and proton transfer to proton pumping in cytochrome c oxidase, we present the results of our earlier and recent density functional theory calculations for the dinuclear Fe-a3-CuB reaction center in this enzyme. A specific catalytic reaction wheel diagram is constructed from the calculations, based on the structures and relative energies of the intermediate states of the reaction cycle. A larger family of tautomers/protonation states is generated compared to our earlier work, and a new lowest-energy pathway is proposed. The entire reaction cycle is calculated for the new smaller model (about 185-190 atoms), and two selected arcs of the wheel are chosen for calculations using a larger model (about 205 atoms). We compare the structural and redox energetics and protonation calculations with available experimental data. The reaction cycle map that we have built is positioned for further improvement and testing against experiment.
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Affiliation(s)
- Louis Noodleman
- Department
of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, TPC15, La Jolla, California 92037, United States
| | - Wen-Ge Han Du
- Department
of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, TPC15, La Jolla, California 92037, United States
| | - James
A. Fee
- Department
of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, TPC15, La Jolla, California 92037, United States
| | - Andreas W. Götz
- San Diego Supercomputer
Center and Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, MC0505, La Jolla, California 92093, United States
| | - Ross C. Walker
- San Diego Supercomputer
Center and Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, MC0505, La Jolla, California 92093, United States
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87
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Einarsdóttir O, McDonald W, Funatogawa C, Szundi I, Woodruff WH, Dyer RB. The pathway of O₂to the active site in heme-copper oxidases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:109-18. [PMID: 24998308 DOI: 10.1016/j.bbabio.2014.06.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 06/24/2014] [Indexed: 11/16/2022]
Abstract
The route of O₂to and from the high-spin heme in heme-copper oxidases has generally been believed to emulate that of carbon monoxide (CO). Time-resolved and stationary infrared experiments in our laboratories of the fully reduced CO-bound enzymes, as well as transient optical absorption saturation kinetics studies as a function of CO pressure, have provided strong support for CO binding to CuB⁺ on the pathway to and from the high-spin heme. The presence of CO on CuB⁺ suggests that O₂binding may be compromised in CO flow-flash experiments. Time-resolved optical absorption studies show that the rate of O₂and NO binding in the bovine enzyme (1 × 10⁸M⁻¹s⁻¹) is unaffected by the presence of CO, which is consistent with the rapid dissociation (t½ = 1.5μs) of CO from CuB⁺. In contrast, in Thermus thermophilus (Tt) cytochrome ba3 the O₂and NO binding to heme a3 slows by an order of magnitude in the presence of CO (from 1 × 10⁹ to 1 × 10⁸M⁻¹s⁻¹), but is still considerably faster (~10μs at 1atm O₂) than the CO off-rate from CuB in the absence of O₂(milliseconds). These results show that traditional CO flow-flash experiments do not give accurate results for the physiological binding of O₂and NO in Tt ba3, namely, in the absence of CO. They also raise the question whether in CO flow-flash experiments on Tt ba3 the presence of CO on CuB⁺ impedes the binding of O₂to CuB⁺ or, if O₂does not bind to CuB⁺ prior to heme a3, whether the CuB⁺-CO complex sterically restricts access of O₂to the heme. Both possibilities are discussed, and we argue that O₂binds directly to heme a3 in Tt ba3, causing CO to dissociate from CuB⁺ in a concerted manner through steric and/or electronic effects. This would allow CuB⁺ to function as an electron donor during the fast (5μs) breaking of the OO bond. These results suggest that the binding of CO to CuB⁺ on the path to and from heme a3 may not be applicable to O₂and NO in all heme-copper oxidases. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
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Affiliation(s)
- Olöf Einarsdóttir
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
| | - William McDonald
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Chie Funatogawa
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Istvan Szundi
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | | | - R Brian Dyer
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
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88
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Morgada MN, Abriata LA, Zitare U, Alvarez-Paggi D, Murgida DH, Vila AJ. Control of the Electronic Ground State on an Electron-Transfer Copper Site by Second-Sphere Perturbations. Angew Chem Int Ed Engl 2014; 53:6188-92. [DOI: 10.1002/anie.201402083] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 02/24/2014] [Indexed: 01/07/2023]
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89
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Morgada MN, Abriata LA, Zitare U, Alvarez-Paggi D, Murgida DH, Vila AJ. Control of the Electronic Ground State on an Electron-Transfer Copper Site by Second-Sphere Perturbations. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201402083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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90
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Liu J, Chakraborty S, Hosseinzadeh P, Yu Y, Tian S, Petrik I, Bhagi A, Lu Y. Metalloproteins containing cytochrome, iron-sulfur, or copper redox centers. Chem Rev 2014; 114:4366-469. [PMID: 24758379 PMCID: PMC4002152 DOI: 10.1021/cr400479b] [Citation(s) in RCA: 559] [Impact Index Per Article: 55.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Indexed: 02/07/2023]
Affiliation(s)
- Jing Liu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Saumen Chakraborty
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Parisa Hosseinzadeh
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yang Yu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Shiliang Tian
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Igor Petrik
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Ambika Bhagi
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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91
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Solomon EI, Heppner DE, Johnston EM, Ginsbach JW, Cirera J, Qayyum M, Kieber-Emmons MT, Kjaergaard CH, Hadt RG, Tian L. Copper active sites in biology. Chem Rev 2014; 114:3659-853. [PMID: 24588098 PMCID: PMC4040215 DOI: 10.1021/cr400327t] [Citation(s) in RCA: 1135] [Impact Index Per Article: 113.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | - David E. Heppner
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Jordi Cirera
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Munzarin Qayyum
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | | | - Ryan G. Hadt
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Li Tian
- Department of Chemistry, Stanford University, Stanford, CA, 94305
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92
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Rauhamäki V, Wikström M. The causes of reduced proton-pumping efficiency in type B and C respiratory heme-copper oxidases, and in some mutated variants of type A. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:999-1003. [PMID: 24583065 DOI: 10.1016/j.bbabio.2014.02.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 01/27/2014] [Accepted: 02/17/2014] [Indexed: 12/11/2022]
Abstract
The heme-copper oxidases may be divided into three categories, A, B, and C, which include cytochrome c and quinol-oxidising enzymes. All three types are known to be proton pumps and are found in prokaryotes, whereas eukaryotes only contain A-type cytochrome c oxidase in their inner mitochondrial membrane. However, the bacterial B- and C-type enzymes have often been reported to pump protons with an H(+)/e(-) ratio of only one half of the unit stoichiometry in the A-type enzyme. We will show here that these observations are likely to be the result of difficulties with the measuring technique together with a higher sensitivity of the B- and C-type enzymes to the protonmotive force that opposes pumping. We find that under optimal conditions the H(+)/e(-) ratio is close to unity in all the three heme-copper oxidase subfamilies. A higher tendency for proton leak in the B- and C-type enzymes may result from less efficient gating of a proton pump mechanism that we suggest evolved before the so-called D-channel of proton transfer. There is also a discrepancy between results using whole bacterial cells vs. phospholipid vesicles inlaid with oxidase with respect to the observed proton pumping after modification of the D-channel residue asparagine-139 (Rhodobacter sphaeroides numbering) to aspartate in A-type cytochrome c oxidase. This discrepancy might also be explained by a higher sensitivity of proton pumping to protonmotive force in the mutated variant. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.
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Affiliation(s)
- Virve Rauhamäki
- Institute of Biotechnology, University of Helsinki, Viikinkaari 1, 00014 Helsinki, Finland
| | - Mårten Wikström
- Institute of Biotechnology, University of Helsinki, Viikinkaari 1, 00014 Helsinki, Finland.
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93
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Du WGH, Noodleman L. Density functional study for the bridged dinuclear center based on a high-resolution X-ray crystal structure of ba3 cytochrome c oxidase from Thermus thermophilus. Inorg Chem 2013; 52:14072-88. [PMID: 24262070 DOI: 10.1021/ic401858s] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Strong electron density for a peroxide type dioxygen species bridging the Fea3 and CuB dinuclear center (DNC) was observed in the high-resolution (1.8 Å) X-ray crystal structures (PDB entries 3S8G and 3S8F) of ba3 cytochrome c oxidase (CcO) from Thermus thermophilus. The crystals represent the as-isolated X-ray photoreduced CcO structures. The bridging peroxide was proposed to arise from the recombination of two radiation-produced HO(•) radicals formed either very near to or even in the space between the two metals of the DNC. It is unclear whether this peroxide species is in the O2(2-), O2(•)(-), HO2(-), or the H2O2 form and what is the detailed electronic structure and binding geometry including the DNC. In order to answer what form of this dioxygen species was observed in the DNC of the 1.8 Å X-ray CcO crystal structure (3S8G), we have applied broken-symmetry density functional theory (BS-DFT) geometric and energetic calculations (using OLYP potential) on large DNC cluster models with different Fea3-CuB oxidation and spin states and with O2(2-), O2(•)(-), HO2(-), or H2O2 in the bridging position. By comparing the DFT optimized geometries with the X-ray crystal structure (3S8G), we propose that the bridging peroxide is HO2(-). The X-ray crystal structure is likely to represent the superposition of the Fea3(2+)-(HO2(-))-CuB(+) DNC's in different states (Fe(2+) in low spin (LS), intermediate spin (IS), or high spin (HS)) with the majority species having the proton of the HO2(-) residing on the oxygen atom (O1) which is closer to the Fea3(2+) site in the Fea3(2+)-(HO-O)(-)-CuB(+) conformation. Our calculations show that the side chain of Tyr237 is likely trapped in the deprotonated Tyr237(-) anion form in the 3S8G X-ray crystal structure.
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Affiliation(s)
- Wen-Ge Han Du
- Department of Integrative Structural and Computational Biology, TPC15, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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94
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Abstract
Laboratory-adapted strains of Thermus spp. have been shown to require oxygen for growth, including the model strains T. thermophilus HB27 and HB8. In contrast, many isolates of this species that have not been intensively grown under laboratory conditions keep the capability to grow anaerobically with one or more electron acceptors. The use of nitrogen oxides, especially nitrate, as electron acceptors is one of the most widespread capabilities among these facultative strains. In this process, nitrate is reduced to nitrite by a reductase (Nar) that also functions as electron transporter toward nitrite and nitric oxide reductases when nitrate is scarce, effectively replacing respiratory complex III. In many T. thermophilus denitrificant strains, most electrons for Nar are provided by a new class of NADH dehydrogenase (Nrc). The ability to reduce nitrite to NO and subsequently to N2O by the corresponding Nir and Nor reductases is also strain specific. The genes encoding the capabilities for nitrate (nar) and nitrite (nir and nor) respiration are easily transferred between T. thermophilus strains by natural competence or by a conjugation-like process and may be easily lost upon continuous growth under aerobic conditions. The reason for this instability is apparently related to the fact that these metabolic capabilities are encoded in gene cluster islands, which are delimited by insertion sequences and integrated within highly variable regions of easily transferable extrachromosomal elements. Together with the chromosomal genes, these plasmid-associated genetic islands constitute the extended pangenome of T. thermophilus that provides this species with an enhanced capability to adapt to changing environments.
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95
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Smirnova I, Chang HY, von Ballmoos C, Ädelroth P, Gennis RB, Brzezinski P. Single mutations that redirect internal proton transfer in the ba3 oxidase from Thermus thermophilus. Biochemistry 2013; 52:7022-30. [PMID: 24004023 DOI: 10.1021/bi4008726] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The ba3-type cytochrome c oxidase from Thermus thermophilus is a membrane-bound proton pump. Results from earlier studies have shown that with the aa3-type oxidases proton uptake to the catalytic site and "pump site" occurs simultaneously. However, with ba3 oxidase the pump site is loaded before proton transfer to the catalytic site because the proton transfer to the latter is slower than that with the aa3 oxidases. In addition, the timing of formation and decay of catalytic intermediates is different in the two types of oxidases. In the present study, we have investigated two mutant ba3 CytcOs in which residues of the proton pathway leading to the catalytic site as well as the pump site were exchanged, Thr312Val and Tyr244Phe. Even though ba3 CytcO uses only a single proton pathway for transfer of the substrate and "pumped" protons, the amino-acid residue substitutions had distinctly different effects on the kinetics of proton transfer to the catalytic site and the pump site. The results indicate that the rates of these reactions can be modified independently by replacement of single residues within the proton pathway. Furthermore, the data suggest that the Thr312Val and Tyr244Phe mutations interfere with a structural rearrangement in the proton pathway that is rate limiting for proton transfer to the catalytic site.
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Affiliation(s)
- Irina Smirnova
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University , SE-106 91 Stockholm, Sweden
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96
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Abriata LA, Vila AJ. Redox-state sensing by hydrogen bonds in the CuA center of cytochrome c oxidase. J Inorg Biochem 2013; 132:18-20. [PMID: 24012017 DOI: 10.1016/j.jinorgbio.2013.07.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/18/2013] [Accepted: 07/23/2013] [Indexed: 11/25/2022]
Abstract
Cytochrome c oxidases (CcO) couple electron transfer to active proton translocation through a gated mechanism that minimizes energy losses by preventing protons from flowing backwards or leaking. Such a complex mechanism requires that information about the redox and protonation states of the different centers be transmitted between different parts of the oxidase. Here we report a network of residues located around the electron entry point of CcO, the CuA site in subunit II, that experience collective pH equilibria around neutral pH. This network starts at the occluded side of the CuA site and extends to the interface between subunits I and II of the CcO, where the proton exit is located and through which electrons flow into subunit I. One of the residues in this network is directly involved in a hydrogen bond to one of the CuA ligands, whose strength is highly sensitive to the redox state of the metal center. We propose that this interaction mediates the transmission of redox changes from ET centers to other functional regions of the oxidase, and possibly also in other similar machineries, as part of their gating and regulatory mechanisms.
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Affiliation(s)
- Luciano A Abriata
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
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97
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Current advances in research of cytochrome c oxidase. Amino Acids 2013; 45:1073-87. [PMID: 23999646 DOI: 10.1007/s00726-013-1585-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 08/21/2013] [Indexed: 12/13/2022]
Abstract
The function of cytochrome c oxidase as a biomolecular nanomachine that transforms energy of redox reaction into protonmotive force across a biological membrane has been subject of intense research, debate, and controversy. The structure of the enzyme has been solved for several organisms; however details of its molecular mechanism of proton pumping still remain elusive. Particularly, the identity of the proton pumping site, the key element of the mechanism, is still open to dispute. The pumping mechanism has been for a long time one of the key unsolved issues of bioenergetics and biochemistry, but with the accelerating progress in this field many important details and principles have emerged. Current advances in cytochrome oxidase research are reviewed here, along with a brief discussion of the most complete proton pumping mechanism proposed to date, and a molecular basis for control of its efficiency.
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98
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Turk D. MAIN software for density averaging, model building, structure refinement and validation. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:1342-57. [PMID: 23897458 PMCID: PMC3727325 DOI: 10.1107/s0907444913008408] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 03/26/2013] [Indexed: 11/11/2022]
Abstract
MAIN is software that has been designed to interactively perform the complex tasks of macromolecular crystal structure determination and validation. Using MAIN, it is possible to perform density modification, manual and semi-automated or automated model building and rebuilding, real- and reciprocal-space structure optimization and refinement, map calculations and various types of molecular structure validation. The prompt availability of various analytical tools and the immediate visualization of molecular and map objects allow a user to efficiently progress towards the completed refined structure. The extraordinary depth perception of molecular objects in three dimensions that is provided by MAIN is achieved by the clarity and contrast of colours and the smooth rotation of the displayed objects. MAIN allows simultaneous work on several molecular models and various crystal forms. The strength of MAIN lies in its manipulation of averaged density maps and molecular models when noncrystallographic symmetry (NCS) is present. Using MAIN, it is possible to optimize NCS parameters and envelopes and to refine the structure in single or multiple crystal forms.
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Affiliation(s)
- Dušan Turk
- Biochemistry and Molecular and Structural Biology, Jozef Stefan Institute, Jamova 39, Ljubljana, Slovenia.
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99
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Characterization of the nitric oxide reductase from Thermus thermophilus. Proc Natl Acad Sci U S A 2013; 110:12613-8. [PMID: 23858452 DOI: 10.1073/pnas.1301731110] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitrous oxide (N2O) is a powerful greenhouse gas implicated in climate change. The dominant source of atmospheric N2O is incomplete biological dentrification, and the enzymes responsible for the release of N2O are NO reductases. It was recently reported that ambient emissions of N2O from the Great Boiling Spring in the United States Great Basin are high, and attributed to incomplete denitrification by Thermus thermophilus and related bacterial species [Hedlund BP, et al. (2011) Geobiology 9(6)471-480]. In the present work, we have isolated and characterized the NO reductase (NOR) from T. thermophilus. The enzyme is a member of the cNOR family of enzymes and belongs to a phylogenetic clade that is distinct from previously examined cNORs. Like other characterized cNORs, the T. thermophilus cNOR consists of two subunits, NorB and NorC, and contains a one heme c, one Ca(2+), a low-spin heme b, and an active site consisting of a high-spin heme b and FeB. The roles of conserved residues within the cNOR family were investigated by site-directed mutagenesis. The most important and unexpected result is that the glutamic acid ligand to FeB is not essential for function. The E211A mutant retains 68% of wild-type activity. Mutagenesis data and the pattern of conserved residues suggest that there is probably not a single pathway for proton delivery from the periplasm to the active site that is shared by all cNORs, and that there may be multiple pathways within the T. thermophilus cNOR.
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100
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Ghosh MK, Basak P, Mazumdar S. Mechanism of copper incorporation in subunit II of cytochrome C oxidase from Thermus thermophilus: identification of intermediate species. Biochemistry 2013; 52:4620-35. [PMID: 23745508 DOI: 10.1021/bi400101g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Detailed spectroscopic and kinetic studies of incorporation of copper ion in the wild type (WT) and the D111AA (AA = K, N, or E) mutants of the metal ion binding site of the soluble fragment of subunit II of cytochrome c oxidase from Thermus thermophilus (TtCuA) showed the formation of at least two distinct intermediates. The global analyses of the multiwavelength kinetic results suggested a four-step reaction scheme involving two distinct intermediates in the pathway of incorporation of copper ions into the apoprotein forming the purple dinuclear CuA. An early intermediate similar to the red copper binding proteins was detected in the WT as well as in all the mutants. The second intermediate was a green copper species in the case of WT TtCuA. Mutation of Asp111, however, formed a second intermediate that is distinctly different from that formed in the case of the WT protein, suggesting that mutants follow pathways of copper ion incorporation different from that in the WT protein. The electrostatic interaction between Asp111 and the coordinating His114 possibly plays a subtle role in the mechanism of incorporation of metal ion into the protein. The overall Kd for WT TtCuA was found to be ~8 nM, which changed with mutation of the Asp111 residue. The activation and thermodynamic parameters were also determined from the temperature- and pH-dependent multiwavelength kinetics, and the results are discussed to unravel the role of Asp111 in the mechanism of formation of the dinuclear CuA center in cytochrome c oxidase.
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Affiliation(s)
- Manas Kumar Ghosh
- Department of Chemical Sciences, Tata Institute of Fundamental Research , Colaba, Mumbai 400005, India
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