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Santema LL, Rozeboom HJ, Borger VP, Kaya SG, Fraaije MW. Identification of a robust bacterial pyranose oxidase which displays an unusual pH dependence. J Biol Chem 2024:107885. [PMID: 39395808 DOI: 10.1016/j.jbc.2024.107885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2024] [Revised: 09/30/2024] [Accepted: 10/06/2024] [Indexed: 10/14/2024] Open
Abstract
Pyranose oxidases are valuable biocatalysts, yet only a handful of bacterial pyranose oxidases are known. These bacterial enzymes exhibit noteworthy distinctions from their extensively characterized fungal counterparts, encompassing variations in substrate specificity and structural attributes. Herein a bacterial pyranose oxidase from Oscillatoria princeps (OPOx) was biochemically characterized in detail. In contrast to the fungal pyranose oxidases, OPOx could be well expressed in Escherichia coli as soluble, fully flavinylated and active oxidase. It was found to be highly thermostable (melting temperature >90 ⁰C) and showed activity on glucose, exhibiting an exceptionally low KM value (48 μM). Elucidation of its crystal structure revealed similarities with fungal pyranose oxidases, such as being a tetramer with a large central void leading to a narrow substrate access tunnel. In the active site, the FAD cofactor is covalently bound to a histidine. OPOx displays a relatively narrow pH optimum for activity with a sharp decline at relatively basic pH values which is accompanied with a drastic change in its flavin absorbance spectrum. The pH-dependent switch in flavin absorbance features and oxidase activity was shown to be fully reversible. It is hypothesized that a glutamic acid helps to stabilize the protonated form of the histidine that is tethered to the FAD. OPOx presents itself as a valuable biocatalyst as it is highly robust, well-expressed in E. coli, shows low KM values for monosaccharides and has a peculiar pH dependent "on-off switch".
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Affiliation(s)
- Lars L Santema
- Molecular Enzymology, University of Groningen, Nijenborgh 3, 9747AG Groningen, The Netherlands
| | - Henriëtte J Rozeboom
- Molecular Enzymology, University of Groningen, Nijenborgh 3, 9747AG Groningen, The Netherlands
| | - Veronica P Borger
- Molecular Enzymology, University of Groningen, Nijenborgh 3, 9747AG Groningen, The Netherlands
| | - Saniye G Kaya
- Molecular Enzymology, University of Groningen, Nijenborgh 3, 9747AG Groningen, The Netherlands
| | - Marco W Fraaije
- Molecular Enzymology, University of Groningen, Nijenborgh 3, 9747AG Groningen, The Netherlands.
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Quaye JA, Wood KE, Snelgrove C, Ouedraogo D, Gadda G. An active site mutation induces oxygen reactivity in D-arginine dehydrogenase: A case of superoxide diverting protons. J Biol Chem 2024; 300:107381. [PMID: 38762175 PMCID: PMC11193025 DOI: 10.1016/j.jbc.2024.107381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 05/09/2024] [Accepted: 05/13/2024] [Indexed: 05/20/2024] Open
Abstract
Enzymes are potent catalysts that increase biochemical reaction rates by several orders of magnitude. Flavoproteins are a class of enzymes whose classification relies on their ability to react with molecular oxygen (O2) during catalysis using ionizable active site residues. Pseudomonas aeruginosa D-arginine dehydrogenase (PaDADH) is a flavoprotein that oxidizes D-arginine for P. aeruginosa survival and biofilm formation. The crystal structure of PaDADH reveals the interaction of the glutamate 246 (E246) side chain with the substrate and at least three other active site residues, establishing a hydrogen bond network in the active site. Additionally, E246 likely ionizes to facilitate substrate binding during PaDADH catalysis. This study aimed to investigate how replacing the E246 residue with leucine affects PaDADH catalysis and its ability to react with O2 using steady-state kinetics coupled with pH profile studies. The data reveal a gain of O2 reactivity in the E246L variant, resulting in a reduced flavin semiquinone species and superoxide (O2•-) during substrate oxidation. The O2•- reacts with active site protons, resulting in an observed nonstoichiometric slope of 1.5 in the enzyme's log (kcat/Km) pH profile with D-arginine. Adding superoxide dismutase results in an observed correction of the slope to 1.0. This study demonstrates how O2•- can alter the slopes of limbs in the pH profiles of flavin-dependent enzymes and serves as a model for correcting nonstoichiometric slopes in elucidating reaction mechanisms of flavoproteins.
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Affiliation(s)
- Joanna A Quaye
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA
| | - Kendall E Wood
- Biology Department, Morehouse College, Atlanta, Georgia, USA
| | - Claire Snelgrove
- The Gwinnett School of Mathematics, Science, and Technology, Lawrenceville, Georgia, USA
| | - Daniel Ouedraogo
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA
| | - Giovanni Gadda
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA; Department of Biology, Georgia State University, Atlanta, Georgia, USA; Department of the Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA.
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3
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Kaushik S, Rameshwari R, Chapadgaonkar SS. The in-silico study of the structural changes in the Arthrobacter globiformis choline oxidase induced by high temperature. J Genet Eng Biotechnol 2024; 22:100348. [PMID: 38494262 PMCID: PMC10980864 DOI: 10.1016/j.jgeb.2023.100348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 12/03/2023] [Indexed: 03/19/2024]
Abstract
BACKGROUND Choline oxidase, a flavoprotein, is an enzyme that catalyzes the reaction which converts choline into glycine betaine. Choline oxidase started its journey way back in 1933. However, the impact of the high temperature on its structure has not been explored despite the long history and availability of its crystal structure. Both choline oxidase and its product, glycine betaine, have enormous applications spanning across multiple industries. Understanding how the 3D structure of the enzyme will change with the temperature change can open new ways to make it more stable and useful for industry. PROCESS This research paper presents the in-silico study and analysis of the structural changes of A. globiformis choline oxidase at temperatures from 25 °C to 60 °C. A step-wise process is depicted in Fig. 1. RESULTS Multiple sequence alignment (MSA) of 11 choline oxidase sequences from different bacteria vs Arthrobacter globiformis choline oxidase showed that active site residues are highly conserved. The available crystal structure of A. globiformis choline oxidase with cofactor Flavin Adenine Dinucleotide (FAD) in the dimeric state (PDB ID: 4MJW)1 was considered for molecular dynamics simulations. A simulated annealing option was used to gradually increase the temperature of the system from 25 °C to 60 °C. Analysis of the conserved residues, as well as residues involved in Flavin Adenine Dinucleotide (FAD) binding, substrate binding, substate gating, and dimer formationwas done. At high temperatures, the formation of the inter-chain salt bridge between Arg50 and Glu63 was a significant observation near the active site of choline oxidase. CONCLUSION Molecular dynamics studies suggest that an increase in temperature has a significant impact on the extended Flavin Adenine Dinucleotide (FAD) binding region. These changes interfere with the entry of substrate to the active site of the enzyme and make the enzyme inactive.
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Affiliation(s)
- Sonia Kaushik
- Department of Biotechnology, School of Engineering and Technology, Manav Rachna International Institute of Research and Studies, Faridabad, Haryana, India
| | - Rashmi Rameshwari
- Department of Biotechnology, School of Engineering and Technology, Manav Rachna International Institute of Research and Studies, Faridabad, Haryana, India.
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Quaye JA, Gadda G. The Pseudomonas aeruginosa PAO1 metallo flavoprotein d-2-hydroxyglutarate dehydrogenase requires Zn 2+ for substrate orientation and activation. J Biol Chem 2023; 299:103008. [PMID: 36775127 PMCID: PMC10034468 DOI: 10.1016/j.jbc.2023.103008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 02/12/2023] Open
Abstract
Pseudomonas aeruginosa PAO1 d-2-hydroxyglutarate (D2HG) dehydrogenase (PaD2HGDH) oxidizes D2HG to 2-ketoglutarate during the vital l-serine biosynthesis and is a potential therapeutic target against P. aeruginosa. PaD2HGDH, which oxidizes d-malate as an alternative substrate, has been demonstrated to be a metallo flavoprotein that requires Zn2+ for activity. However, the role of Zn2+ in the enzyme has not been elucidated, making it difficult to rationalize why nature employs both a redox center and a metal ion for catalysis in PaD2HGDH and other metallo flavoenzymes. In this study, recombinant His-tagged PaD2HGDH was purified to high levels in the presence of Zn2+ or Co2+ to investigate the metal's role in catalysis. We found that the flavin reduction step was reversible and partially rate limiting for the enzyme's turnover at pH 7.4 with either D2HG or d-malate with similar rate constants for both substrates, irrespective of whether Zn2+ or Co2+ was bound to the enzyme. The steady-state pL profiles of the kcat and kcat/Km values with d-malate demonstrate that Zn2+ mediates the activation of water coordinated to the metal. Our data are consistent with a dual role for the metal, which orients the hydroxy acid substrate in the enzyme's active site and rapidly deprotonates the substrate to yield an alkoxide species for hydride transfer to the flavin. Thus, we propose a catalytic mechanism for PaD2HGDH oxidation that establishes Zn2+ as a cofactor required for substrate orientation and activation during enzymatic turnover.
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Affiliation(s)
- Joanna A Quaye
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA
| | - Giovanni Gadda
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA; Department of Biology, Georgia State University, Atlanta, Georgia, USA; Department of The Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA.
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5
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Ultrafast photooxidation of protein-bound anionic flavin radicals. Proc Natl Acad Sci U S A 2022; 119:2118924119. [PMID: 35181610 PMCID: PMC8872763 DOI: 10.1073/pnas.2118924119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2022] [Indexed: 12/17/2022] Open
Abstract
Flavoproteins are colored proteins involved in a large variety of biochemical reactions. They can perform photochemical reactions, which are increasingly exploited for bioengineering new protein-derived photocatalysts. In particular, light-induced reduction of the resting oxidized state of the flavin by close-lying amino acids or substrates is extensively studied. Here, we demonstrate that the reverse and previously unknown reaction photooxidation of the anionic semireduced flavin radical, a short-lived reaction intermediate in many biochemical reactions, efficiently occurs in flavoprotein oxidases. We anticipate that this finding will allow photoreduction of external reactants and lead to exploration of novel photocatalytic pathways. The photophysical properties of anionic semireduced flavin radicals are largely unknown despite their importance in numerous biochemical reactions. Here, we studied the photoproducts of these intrinsically unstable species in five different flavoprotein oxidases where they can be stabilized, including the well-characterized glucose oxidase. Using ultrafast absorption and fluorescence spectroscopy, we unexpectedly found that photoexcitation systematically results in the oxidation of protein-bound anionic flavin radicals on a time scale of less than ∼100 fs. The thus generated photoproducts decay back in the remarkably narrow 10- to 20-ps time range. Based on molecular dynamics and quantum mechanics computations, positively charged active-site histidine and arginine residues are proposed to be the electron acceptor candidates. Altogether, we established that, in addition to the commonly known and extensively studied photoreduction of oxidized flavins in flavoproteins, the reverse process (i.e., the photooxidation of anionic flavin radicals) can also occur. We propose that this process may constitute an excited-state deactivation pathway for protein-bound anionic flavin radicals in general. This hitherto undocumented photochemical reaction in flavoproteins further extends the family of flavin photocycles.
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6
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Abstract
Choline oxidase catalyzes the four-electron, two-step, flavin-mediated oxidation of choline to glycine betaine. The enzyme is important both for medical and biotechnological reasons, because glycine betaine is one among a limited number of compatible solutes used by cells to counteract osmotic pressure. From a fundamental standpoint, choline oxidase has emerged as one of the paradigm enzymes for the oxidation of alcohols catalyzed by flavoproteins. Mechanistic, structural, and computational studies have elucidated the mechanism of action of the enzyme from Arthrobacter globiformis at the molecular level. Both choline and oxygen access to the active site cavity are gated and tightly controlled. Amino acid residues involved in substrate binding, and their contribution, have been identified. The mechanism of choline oxidation, with a hydride transfer reaction, an asynchronous transition state, the formation and stabilization of an alkoxide transient species, and a quantum mechanical mode of reaction, has been elucidated. The importance of nonpolar side chains for oxygen localization and of the positive charge harbored on the substrate for activation of oxygen for reaction with the reduced flavin have been recognized. Interesting phenomena, like the formation of a metastable photoinduced flavin-protein adduct, the reversible formation of a bicovalent flavoprotein, and the trapping of the enzyme in inactive conformations, have been described. This review summarizes the current status of our understanding on the structure-function-dynamics of choline oxidase.
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Affiliation(s)
- Giovanni Gadda
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, United States; Department of Biology, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, United States.
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7
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Su D, Smitherman C, Gadda G. A Metastable Photoinduced Protein–Flavin Adduct in Choline Oxidase, an Enzyme Not Involved in Light-Dependent Processes. J Phys Chem B 2020; 124:3936-3943. [DOI: 10.1021/acs.jpcb.0c02633] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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8
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Romero E, Gómez Castellanos JR, Gadda G, Fraaije MW, Mattevi A. Same Substrate, Many Reactions: Oxygen Activation in Flavoenzymes. Chem Rev 2018; 118:1742-1769. [DOI: 10.1021/acs.chemrev.7b00650] [Citation(s) in RCA: 216] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Elvira Romero
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - J. Rubén Gómez Castellanos
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy
| | - Giovanni Gadda
- Departments of Chemistry and Biology, Center for Diagnostics and Therapeutics, and Center for Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia 30302-3965, United States
| | - Marco W. Fraaije
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Andrea Mattevi
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy
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9
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Dourado DFAR, Swart M, Carvalho ATP. Why the Flavin Adenine Dinucleotide (FAD) Cofactor Needs To Be Covalently Linked to Complex II of the Electron-Transport Chain for the Conversion of FADH 2 into FAD. Chemistry 2017; 24:5246-5252. [PMID: 29124817 PMCID: PMC5969107 DOI: 10.1002/chem.201704622] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/07/2017] [Indexed: 11/10/2022]
Abstract
A covalently bound flavin cofactor is predominant in the succinate‐ubiquinone oxidoreductase (SQR; Complex II), an essential component of aerobic electron transport, and in the menaquinol‐fumarate oxidoreductase (QFR), the anaerobic counterpart, although it is only present in approximately 10 % of the known flavoenzymes. This work investigates the role of this 8α‐N3‐histidyl linkage between the flavin adenine dinucleotide (FAD) cofactor and the respiratory Complex II. After parameterization with DFT calculations, classical molecular‐dynamics simulations and quantum‐mechanics calculations for Complex II:FAD and Complex II:FADH2, with and without the covalent bond, were performed. It was observed that the covalent bond is essential for the active‐center arrangement of the FADH2/FAD cofactor. Removal of this bond causes a displacement of the isoalloxazine group, which influences interactions with the protein, flavin solvation, and possible proton‐transfer pathways. Specifically, for the noncovalently bound FADH2 cofactor, the N1 atom moves away from the His‐A365 and His‐A254 residues and the N5 atom moves away from the glutamine‐62A residue. Both of the histidine and glutamine residues interact with a chain of water molecules that cross the enzyme, which is most likely involved in proton transfer. Breaking this chain of water molecules could thereby compromise proton transfer across the two active sites of Complex II.
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Affiliation(s)
- Daniel F A R Dourado
- School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, Northern Ireland, UK.,Almac Sciences, Department of Biocatalysis and Isotope Chemistry, Almac House, 20 Seagoe Industrial Estate, Craigavon, BT63 5QD, Northern Ireland, UK
| | - Marcel Swart
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, 17003, Girona, Spain.,ICREA, Pg. Lluís Companys 23, 08010, Barcelona, Spain
| | - Alexandra T P Carvalho
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal
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10
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Su D, Yuan H, Gadda G. A Reversible, Charge-Induced Intramolecular C4a-S-Cysteinyl-Flavin in Choline Oxidase Variant S101C. Biochemistry 2017; 56:6677-6690. [DOI: 10.1021/acs.biochem.7b00958] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Dan Su
- Department
of Chemistry, ‡Department of Biology, §Center for Diagnostics and Therapeutics, and ∥Center for Biotechnology
and Drug Design, Georgia State University, Atlanta, Georgia 30302, United States
| | - Hongling Yuan
- Department
of Chemistry, ‡Department of Biology, §Center for Diagnostics and Therapeutics, and ∥Center for Biotechnology
and Drug Design, Georgia State University, Atlanta, Georgia 30302, United States
| | - Giovanni Gadda
- Department
of Chemistry, ‡Department of Biology, §Center for Diagnostics and Therapeutics, and ∥Center for Biotechnology
and Drug Design, Georgia State University, Atlanta, Georgia 30302, United States
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11
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Gadda G, Yuan H. Substitutions of S101 decrease proton and hydride transfers in the oxidation of betaine aldehyde by choline oxidase. Arch Biochem Biophys 2017; 634:76-82. [PMID: 29029877 DOI: 10.1016/j.abb.2017.10.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 10/06/2017] [Accepted: 10/09/2017] [Indexed: 11/25/2022]
Abstract
Choline oxidase oxidizes choline to glycine betaine, with two flavin-mediated reactions to convert the alcohol substrate to the carbon acid product. Proton abstraction from choline or hydrated betaine aldehyde in the wild-type enzyme occurs in the mixing time of the stopped-flow spectrophotometer, thereby precluding a mechanistic investigation. Mutagenesis of S101 rendered the proton transfer reaction amenable to study. Here, we have investigated the aldehyde oxidation reaction catalyzed by the mutant enzymes using steady-state and rapid kinetics with betaine aldehyde. Stopped-flow traces for the reductive half-reaction of the S101T/V/C variants were biphasic, corresponding to the reactions of proton abstraction and hydride transfer. In contrast, the S101A enzyme yielded monophasic traces like wild-type choline oxidase. The rate constants for proton transfer in the S101T/C/V variants decreased logarithmically with increasing hydrophobicity of residue 101, indicating a behavior different from that seen previously with choline for which no correlation was determined. The rate constants for hydride transfer also showed a logarithmic decrease with increasing hydrophobicity at position 101, which was similar to previous results with choline as a substrate for the enzyme. Thus, the hydrophilic character of S101 is necessary not only for efficient hydride transfer but also for the proton abstraction reaction.
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Affiliation(s)
- Giovanni Gadda
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302-3965, United States; Department of Biology, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302-3965, United States; Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302-3965, United States.
| | - Hongling Yuan
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302-3965, United States
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12
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Evidence for proton tunneling and a transient covalent flavin-substrate adduct in choline oxidase S101A. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1470-1478. [PMID: 28843728 DOI: 10.1016/j.bbapap.2017.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 08/08/2017] [Accepted: 08/10/2017] [Indexed: 11/20/2022]
Abstract
The effect of temperature on the reaction of alcohol oxidation catalyzed by choline oxidase was investigated with the S101A variant of choline oxidase. Anaerobic enzyme reduction in a stopped-flow spectrophotometer was biphasic using either choline or 1,2-[2H4]-choline as a substrate. The limiting rate constants klim1 and klim2 at saturating substrate were well separated (klim1/klim2>9), and were >15-fold slower than for wild-type choline oxidase. Solvent deuterium kinetic isotope effects (KIEs) ~4 established that klim1 probes the proton transfer from the substrate hydroxyl to a catalytic base. Primary substrate deuterium KIEs ≥7 demonstrated that klim2 reports on hydride transfer from the choline alkoxide to the flavin. Between 15°C and 39°C the klim1 and klim2 values increased with increasing temperature, allowing for the analyses of H+ and H- transfers using Eyring and Arrhenius formalisms. Temperature-independent KIE on the klim1 value (H2Oklim1/D2Oklim1) suggests that proton transfer occurs within a highly reorganized tunneling-ready-state with a narrow distribution of donor-acceptor distances. Eyring analysis of the klim2 value gave lines with the slope(choline)>slope(D-choline), suggesting kinetic complexity. Spectral evidence for the transient occurrence of a covalent flavin-substrate adduct during the first phase of the anaerobic reaction of S101A CHO with choline is presented, supporting the notion that an important role of amino acid residues in the active site of flavin-dependent enzymes is to eliminate alternative reactions of the versatile enzyme-bound flavin for the reaction that needs to be catalyzed.
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13
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Dijkman WP, Binda C, Fraaije MW, Mattevi A. Structure-Based Enzyme Tailoring of 5-Hydroxymethylfurfural Oxidase. ACS Catal 2015. [DOI: 10.1021/acscatal.5b00031] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Willem P. Dijkman
- Molecular
Enzymology Group, Groningen Biomolecular Sciences and Biotechnology
Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Claudia Binda
- Department
of Biology and Biotechnology, University of Pavia, via Ferrata
1, 27100 Pavia, Italy
| | - Marco W. Fraaije
- Molecular
Enzymology Group, Groningen Biomolecular Sciences and Biotechnology
Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Andrea Mattevi
- Department
of Biology and Biotechnology, University of Pavia, via Ferrata
1, 27100 Pavia, Italy
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14
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Smitherman C, Rungsrisuriyachai K, Germann MW, Gadda G. Identification of the Catalytic Base for Alcohol Activation in Choline Oxidase. Biochemistry 2014; 54:413-21. [DOI: 10.1021/bi500982y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Crystal Smitherman
- Department
of Chemistry, ‡Department of Biology, §Center for Biotechnology and Drug
Design, ∥Center for Diagnostics and Therapeutics, and ⊥Neuroscience Institute, Georgia State University, Atlanta, Georgia 30302-3965, United States
| | - Kunchala Rungsrisuriyachai
- Department
of Chemistry, ‡Department of Biology, §Center for Biotechnology and Drug
Design, ∥Center for Diagnostics and Therapeutics, and ⊥Neuroscience Institute, Georgia State University, Atlanta, Georgia 30302-3965, United States
| | - Markus W. Germann
- Department
of Chemistry, ‡Department of Biology, §Center for Biotechnology and Drug
Design, ∥Center for Diagnostics and Therapeutics, and ⊥Neuroscience Institute, Georgia State University, Atlanta, Georgia 30302-3965, United States
| | - Giovanni Gadda
- Department
of Chemistry, ‡Department of Biology, §Center for Biotechnology and Drug
Design, ∥Center for Diagnostics and Therapeutics, and ⊥Neuroscience Institute, Georgia State University, Atlanta, Georgia 30302-3965, United States
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15
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Salvi F, Wang YF, Weber IT, Gadda G. Structure of choline oxidase in complex with the reaction product glycine betaine. ACTA ACUST UNITED AC 2014; 70:405-13. [DOI: 10.1107/s1399004713029283] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 10/23/2013] [Indexed: 11/10/2022]
Abstract
Choline oxidase fromArthrobacter globiformis, which is involved in the biosynthesis of glycine betaine from choline, has been extensively characterized in its mechanistic and structural properties. Despite the knowledge gained on the enzyme, the details of substrate access to the active site are not fully understood. The `loop-and-lid' mechanism described for the glucose–methanol–choline enzyme superfamily has not been confirmed for choline oxidase. Instead, a hydrophobic cluster on the solvent-accessible surface of the enzyme has been proposed by molecular dynamics to control substrate access to the active site. Here, the crystal structure of the enzyme was solved in complex with glycine betaine at pH 6.0 at 1.95 Å resolution, allowing a structural description of the ligand–enzyme interactions in the active site. This structure is the first of choline oxidase in complex with a physiologically relevant ligand. The protein structures with and without ligand are virtually identical, with the exception of a loop at the dimer interface, which assumes two distinct conformations. The different conformations of loop 250–255 define different accessibilities of the proposed active-site entrance delimited by the hydrophobic cluster on the other subunit of the dimer, suggesting a role in regulating substrate access to the active site.
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Salvi F, Gadda G. Human choline dehydrogenase: medical promises and biochemical challenges. Arch Biochem Biophys 2013; 537:243-52. [PMID: 23906661 PMCID: PMC7094428 DOI: 10.1016/j.abb.2013.07.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 06/24/2013] [Accepted: 07/16/2013] [Indexed: 01/17/2023]
Abstract
Human choline dehydrogenase (CHD) is located in the inner membrane of mitochondria primarily in liver and kidney and catalyzes the oxidation of choline to glycine betaine. Its physiological role is to regulate the concentrations of choline and glycine betaine in the blood and cells. Choline is important for regulation of gene expression, the biosynthesis of lipoproteins and membrane phospholipids and for the biosynthesis of the neurotransmitter acetylcholine; glycine betaine plays important roles as a primary intracellular osmoprotectant and as methyl donor for the biosynthesis of methionine from homocysteine, a required step for the synthesis of the ubiquitous methyl donor S-adenosyl methionine. Recently, CHD has generated considerable medical attention due to its association with various human pathologies, including male infertility, homocysteinuria, breast cancer and metabolic syndrome. Despite the renewed interest, the biochemical characterization of the enzyme has lagged behind due to difficulties in the obtainment of purified, active and stable enzyme. This review article summarizes the medical relevance and the physiological roles of human CHD, highlights the biochemical knowledge on the enzyme, and provides an analysis based on the comparison of the protein sequence with that of bacterial choline oxidase, for which structural and biochemical information is available.
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Affiliation(s)
- Francesca Salvi
- Department of Chemistry, Georgia State University, Atlanta, GA 30302-3965, United States
| | - Giovanni Gadda
- Department of Chemistry, Georgia State University, Atlanta, GA 30302-3965, United States
- Department of Biology, Georgia State University, Atlanta, GA 30302-3965, United States
- The Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30302-3965, United States
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Pathway of glycine betaine biosynthesis in Aspergillus fumigatus. EUKARYOTIC CELL 2013; 12:853-63. [PMID: 23563483 DOI: 10.1128/ec.00348-12] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The choline oxidase (CHOA) and betaine aldehyde dehydrogenase (BADH) genes identified in Aspergillus fumigatus are present as a cluster specific for fungal genomes. Biochemical and molecular analyses of this cluster showed that it has very specific biochemical and functional features that make it unique and different from its plant and bacterial homologs. A. fumigatus ChoAp catalyzed the oxidation of choline to glycine betaine with betaine aldehyde as an intermediate and reduced molecular oxygen to hydrogen peroxide using FAD as a cofactor. A. fumigatus Badhp oxidized betaine aldehyde to glycine betaine with reduction of NAD(+) to NADH. Analysis of the AfchoAΔ::HPH and AfbadAΔ::HPH single mutants and the AfchoAΔAfbadAΔ::HPH double mutant showed that AfChoAp is essential for the use of choline as the sole nitrogen, carbon, or carbon and nitrogen source during the germination process. AfChoAp and AfBadAp were localized in the cytosol of germinating conidia and mycelia but were absent from resting conidia. Characterization of the mutant phenotypes showed that glycine betaine in A. fumigatus functions exclusively as a metabolic intermediate in the catabolism of choline and not as a stress protectant. This study in A. fumigatus is the first molecular, cellular, and biochemical characterization of the glycine betaine biosynthetic pathway in the fungal kingdom.
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Nau-Wagner G, Opper D, Rolbetzki A, Boch J, Kempf B, Hoffmann T, Bremer E. Genetic control of osmoadaptive glycine betaine synthesis in Bacillus subtilis through the choline-sensing and glycine betaine-responsive GbsR repressor. J Bacteriol 2012; 194:2703-14. [PMID: 22408163 PMCID: PMC3347207 DOI: 10.1128/jb.06642-11] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Accepted: 02/27/2012] [Indexed: 11/20/2022] Open
Abstract
Synthesis of the compatible solute glycine betaine confers a considerable degree of osmotic stress tolerance to Bacillus subtilis. This osmoprotectant is produced through the uptake of the precursor choline via the osmotically inducible OpuB and OpuC ABC transporters and a subsequent two-step oxidation process by the GbsB and GbsA enzymes. We characterized a regulatory protein, GbsR, controlling the transcription of both the structural genes for the glycine betaine biosynthetic enzymes (gbsAB) and those for the choline-specific OpuB transporter (opuB) but not of that for the promiscuous OpuC transporter. GbsR acts genetically as a repressor and functions as an intracellular choline sensor. Spectroscopic analysis of the purified GbsR protein showed that it binds the inducer choline with an apparent K(D) (equilibrium dissociation constant) of approximately 165 μM. Based on the X-ray structure of a protein (Mj223) from Methanococcus jannaschii, a homology model for GbsR was derived. Inspection of this GbsR in silico model revealed a possible ligand-binding pocket for choline resembling those of known choline-binding sites present in solute receptors of microbial ABC transporters, e.g., that of the OpuBC ligand-binding protein of the OpuB ABC transporter. GbsR was not only needed to control gbsAB and opuB expression in response to choline availability but also required to genetically tune down glycine betaine production once cellular adjustment to high osmolarity has been achieved. The GbsR regulatory protein from B. subtilis thus records and integrates cellular and environmental signals for both the onset and the repression of the synthesis of the osmoprotectant glycine betaine.
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Affiliation(s)
- Gabriele Nau-Wagner
- Philipps-University Marburg, Department of Biology, Laboratory for Microbiology, Marburg, Germany
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19
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Gadda G. Oxygen Activation in Flavoprotein Oxidases: The Importance of Being Positive. Biochemistry 2012; 51:2662-9. [DOI: 10.1021/bi300227d] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Giovanni Gadda
- Department
of Chemistry, ‡Department of Biology, and §The Center for Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia
30302-4098, United States
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Ortiz M, Wajs EM, Fragoso A, O'Sullivan CK. A bienzymatic amperometric immunosensor exploiting supramolecular construction for ultrasensitive protein detection. Chem Commun (Camb) 2012; 48:1045-7. [DOI: 10.1039/c2cc16177j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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21
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Yuan H, Gadda G. Importance of a Serine Proximal to the C(4a) and N(5) Flavin Atoms for Hydride Transfer in Choline Oxidase. Biochemistry 2011; 50:770-9. [DOI: 10.1021/bi101837u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Giovanni Gadda
- Department of Chemistry
- Department of Biology
- The Center for Biotechnology and Drug Design
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22
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Quaye O, Nguyen T, Gannavaram S, Pennati A, Gadda G. Rescuing of the hydride transfer reaction in the Glu312Asp variant of choline oxidase by a substrate analogue. Arch Biochem Biophys 2010; 499:1-5. [DOI: 10.1016/j.abb.2010.04.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 04/30/2010] [Accepted: 04/30/2010] [Indexed: 10/19/2022]
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Finnegan S, Yuan H, Wang YF, Orville AM, Weber IT, Gadda G. Structural and kinetic studies on the Ser101Ala variant of choline oxidase: catalysis by compromise. Arch Biochem Biophys 2010; 501:207-13. [PMID: 20561507 DOI: 10.1016/j.abb.2010.06.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 06/10/2010] [Accepted: 06/10/2010] [Indexed: 11/27/2022]
Abstract
The oxidation of choline catalyzed by choline oxidase includes two reductive half-reactions where FAD is reduced by the alcohol substrate and by an aldehyde intermediate transiently formed in the reaction. Each reductive half-reaction is followed by an oxidative half-reaction where the reduced flavin is oxidized by oxygen. Here, we have used mutagenesis to prepare the Ser101Ala mutant of choline oxidase and have investigated the impact of this mutation on the structural and kinetic properties of the enzyme. The crystallographic structure of the Ser101Ala enzyme indicates that the only differences between the mutant and wild-type enzymes are the lack of a hydroxyl group on residue 101 and a more planar configuration of the flavin in the mutant enzyme. Kinetics established that replacement of Ser101 with alanine yields a mutant enzyme with increased efficiencies in the oxidative half-reactions and decreased efficiencies in the reductive half-reactions. This is accompanied by a significant decrease in the overall rate of turnover with choline. Thus, this mutation has revealed the importance of a specific residue for the optimization of the overall turnover of choline oxidase, which requires fine-tuning of four consecutive half-reactions for the conversion of an alcohol to a carboxylic acid.
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Affiliation(s)
- Steffan Finnegan
- Department of Chemistry, Georgia State University, Atlanta, GA 30302-4098, USA
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Sucharitakul J, Wongnate T, Chaiyen P. Kinetic Isotope Effects on the Noncovalent Flavin Mutant Protein of Pyranose 2-Oxidase Reveal Insights into the Flavin Reduction Mechanism. Biochemistry 2010; 49:3753-65. [DOI: 10.1021/bi100187b] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jeerus Sucharitakul
- Department of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Henri-Dunant Road, Patumwan, Bangkok 10330, Thailand
| | - Thanyaporn Wongnate
- Department of Biochemistry and Center of Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Pimchai Chaiyen
- Department of Biochemistry and Center of Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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Finnegan S, Agniswamy J, Weber IT, Gadda G. Role of Valine 464 in the Flavin Oxidation Reaction Catalyzed by Choline Oxidase,. Biochemistry 2010; 49:2952-61. [DOI: 10.1021/bi902048c] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Irene T. Weber
- Departments of Chemistry
- Biology
- The Center for Biotechnology and Drug Design
| | - Giovanni Gadda
- Departments of Chemistry
- Biology
- The Center for Biotechnology and Drug Design
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