1
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Schmidt D, Falb N, Serra I, Bellei M, Pfanzagl V, Hofbauer S, Van Doorslaer S, Battistuzzi G, Furtmüller PG, Obinger C. Compound I Formation and Reactivity in Dimeric Chlorite Dismutase: Impact of pH and the Dynamics of the Catalytic Arginine. Biochemistry 2023; 62:835-850. [PMID: 36706455 PMCID: PMC9910045 DOI: 10.1021/acs.biochem.2c00696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/02/2023] [Indexed: 01/28/2023]
Abstract
The heme enzyme chlorite dismutase (Cld) catalyzes the degradation of chlorite to chloride and dioxygen. Many questions about the molecular reaction mechanism of this iron protein have remained unanswered, including the electronic nature of the catalytically relevant oxoiron(IV) intermediate and its interaction with the distal, flexible, and catalytically active arginine. Here, we have investigated the dimeric Cld from Cyanothece sp. PCC7425 (CCld) and two variants having the catalytic arginine R127 (i) hydrogen-bonded to glutamine Q74 (wild-type CCld), (ii) arrested in a salt bridge with a glutamate (Q74E), or (iii) being fully flexible (Q74V). Presented stopped-flow spectroscopic studies demonstrate the initial and transient appearance of Compound I in the reaction between CCld and chlorite at pH 5.0 and 7.0 and the dominance of spectral features of an oxoiron(IV) species (418, 528, and 551 nm) during most of the chlorite degradation period at neutral and alkaline pH. Arresting the R127 in a salt bridge delays chlorite decomposition, whereas increased flexibility accelerates the reaction. The dynamics of R127 does not affect the formation of Compound I mediated by hypochlorite but has an influence on Compound I stability, which decreases rapidly with increasing pH. The decrease in activity is accompanied by the formation of protein-based amino acid radicals. Compound I is demonstrated to oxidize iodide, chlorite, and serotonin but not hypochlorite. Serotonin is able to dampen oxidative damage and inactivation of CCld at neutral and alkaline pH. Presented data are discussed with respect to the molecular mechanism of Cld and the pronounced pH dependence of chlorite degradation.
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Affiliation(s)
- Daniel Schmidt
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
| | - Nikolaus Falb
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
| | - Ilenia Serra
- BIMEF
Laboratory, Department of Chemistry, University
of Antwerp, 2000Antwerp, Belgium
| | - Marzia Bellei
- Department
of Life Sciences, University of Modena and
Reggio Emilia, 41100Modena, Italy
| | - Vera Pfanzagl
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
| | - Stefan Hofbauer
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
| | - Sabine Van Doorslaer
- BIMEF
Laboratory, Department of Chemistry, University
of Antwerp, 2000Antwerp, Belgium
| | - Gianantonio Battistuzzi
- Department
of Chemistry and Geology, University of
Modena and Reggio Emilia, 41100Modena, Italy
| | - Paul G. Furtmüller
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
| | - Christian Obinger
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
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2
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Barnum TP, Coates JD. Chlorine redox chemistry is widespread in microbiology. THE ISME JOURNAL 2023; 17:70-83. [PMID: 36202926 PMCID: PMC9751292 DOI: 10.1038/s41396-022-01317-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 11/07/2022]
Abstract
Chlorine is abundant in cells and biomolecules, yet the biology of chlorine oxidation and reduction is poorly understood. Some bacteria encode the enzyme chlorite dismutase (Cld), which detoxifies chlorite (ClO2-) by converting it to chloride (Cl-) and molecular oxygen (O2). Cld is highly specific for chlorite and aside from low hydrogen peroxide activity has no known alternative substrate. Here, we reasoned that because chlorite is an intermediate oxidation state of chlorine, Cld can be used as a biomarker for oxidized chlorine species. Cld was abundant in metagenomes from various terrestrial habitats. About 5% of bacterial and archaeal genera contain a microorganism encoding Cld in its genome, and within some genera Cld is highly conserved. Cld has been subjected to extensive horizontal gene transfer. Genes found to have a genetic association with Cld include known genes for responding to reactive chlorine species and uncharacterized genes for transporters, regulatory elements, and putative oxidoreductases that present targets for future research. Cld was repeatedly co-located in genomes with genes for enzymes that can inadvertently reduce perchlorate (ClO4-) or chlorate (ClO3-), indicating that in situ (per)chlorate reduction does not only occur through specialized anaerobic respiratory metabolisms. The presence of Cld in genomes of obligate aerobes without such enzymes suggested that chlorite, like hypochlorous acid (HOCl), might be formed by oxidative processes within natural habitats. In summary, the comparative genomics of Cld has provided an atlas for a deeper understanding of chlorine oxidation and reduction reactions that are an underrecognized feature of biology.
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Affiliation(s)
- Tyler P Barnum
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
| | - John D Coates
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA.
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3
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Serra I, Schmidt D, Pfanzagl V, Mlynek G, Hofbauer S, Djinović-Carugo K, Furtmüller PG, García-Rubio I, Van Doorslaer S, Obinger C. Impact of the dynamics of the catalytic arginine on nitrite and chlorite binding by dimeric chlorite dismutase. J Inorg Biochem 2021; 227:111689. [PMID: 34922158 DOI: 10.1016/j.jinorgbio.2021.111689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/15/2021] [Accepted: 12/03/2021] [Indexed: 01/04/2023]
Abstract
Chlorite dismutases (Clds) are heme b containing oxidoreductases able to decompose chlorite to chloride and molecular oxygen. This work analyses the impact of the distal, flexible and catalytic arginine on the binding of anionic angulate ligands like nitrite and the substrate chlorite. Dimeric Cld from Cyanothece sp. PCC7425 was used as a model enzyme. We have investigated wild-type CCld having the distal catalytic R127 hydrogen-bonded to glutamine Q74 and variants with R127 (i) being arrested in a salt-bridge with a glutamate (Q74E), (ii) being fully flexible (Q74V) or (iii) substituted by either alanine (R127A) or lysine (R127K). We present the electronic and spectral signatures of the high-spin ferric proteins and the corresponding low-spin nitrite complexes elucidated by UV-visible, circular dichroism and electron paramagnetic resonance spectroscopies. Furthermore, we demonstrate the impact of the dynamics of R127 on the thermal stability of the respective nitrite adducts and present the X-ray crystal structures of the nitrite complexes of wild-type CCld and the variants Q74V, Q74E and R127A. In addition, the molecular dynamics (MD) and the binding modi of nitrite and chlorite to the ferric wild-type enzyme and the mutant proteins and the interaction of the oxoanions with R127 have been analysed by MD simulations. The findings are discussed with respect to the role(s) of R127 in ligand and chlorite binding and substrate degradation.
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Affiliation(s)
- Ilenia Serra
- BIMEF Laboratory, Department of Chemistry, University of Antwerp, Belgium
| | - Daniel Schmidt
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Vera Pfanzagl
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Georg Mlynek
- Core Facility Biomolecular & Cellular Analysis, University of Natural Resources and Life Sciences, Vienna, Muthgasse 11, A-1190 Vienna, Austria; Department of Structural and Computational Biology, Max Perutz Laboratories, A-1030, Vienna, Austria
| | - Stefan Hofbauer
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Kristina Djinović-Carugo
- Department of Structural and Computational Biology, Max Perutz Laboratories, A-1030, Vienna, Austria; Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 5, SI-1000 Ljubljana, Slovenia
| | - Paul G Furtmüller
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Inés García-Rubio
- Department of Condensed Matter Physics, Faculty of Sciences, University of Zaragoza, 50009 Zaragoza, Spain; Centro Universitario de la Defensa, 50090 Zaragoza, Spain
| | | | - Christian Obinger
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria.
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4
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Püschmann J, Mahor D, de Geus DC, Strampraad MJF, Srour B, Hagen WR, Todorovic S, Hagedoorn PL. Unique Biradical Intermediate in the Mechanism of the Heme Enzyme Chlorite Dismutase. ACS Catal 2021; 11:14533-14544. [PMID: 34888122 PMCID: PMC8650003 DOI: 10.1021/acscatal.1c03432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 11/04/2021] [Indexed: 11/30/2022]
Abstract
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The heme enzyme chlorite
dismutase (Cld) catalyzes O–O bond
formation as part of the conversion of the toxic chlorite (ClO2–) to chloride (Cl–) and
molecular oxygen (O2). Enzymatic O–O bond formation
is rare in nature, and therefore, the reaction mechanism of Cld is
of great interest. Microsecond timescale pre-steady-state kinetic
experiments employing Cld from Azospira oryzae (AoCld), the natural substrate chlorite, and the
model substrate peracetic acid (PAA) reveal the formation of distinct
intermediates. AoCld forms a complex with PAA rapidly,
which is cleaved heterolytically to yield Compound I, which is sequentially
converted to Compound II. In the presence of chlorite, AoCld forms an initial intermediate with spectroscopic characteristics
of a 6-coordinate high-spin ferric substrate adduct, which subsequently
transforms at kobs = 2–5 ×
104 s–1 to an intermediate 5-coordinated
high-spin ferric species. Microsecond-timescale freeze-hyperquench
experiments uncovered the presence of a transient low-spin ferric
species and a triplet species attributed to two weakly coupled amino
acid cation radicals. The intermediates of the chlorite reaction were
not observed with the model substrate PAA. These findings demonstrate
the nature of physiologically relevant catalytic intermediates and
show that the commonly used model substrate may not behave as expected,
which demands a revision of the currently proposed mechanism of Clds.
The transient triplet-state biradical species that we designate as
Compound T is, to the best of our knowledge, unique in heme enzymology.
The results highlight electron paramagnetic resonance spectroscopic
evidence for transient intermediate formation during the reaction
of AoCld with its natural substrate chlorite. In
the proposed mechanism, the heme iron remains ferric throughout the
catalytic cycle, which may minimize the heme moiety’s reorganization
and thereby maximize the enzyme’s catalytic efficiency.
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Affiliation(s)
- Julia Püschmann
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Durga Mahor
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Daniël C. de Geus
- Janssen Vaccines & Prevention, Archimedesweg 4-6, 2333 CN Leiden, The Netherlands
| | - Marc J. F. Strampraad
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Batoul Srour
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Wilfred R. Hagen
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Smilja Todorovic
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Peter-Leon Hagedoorn
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
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5
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Wang B, Zhai Y, Li S, Li C, Zhu Y, Xu M. Catalytic enhancement of hydrogenation reduction and oxygen transfer reaction for perchlorate removal: A review. CHEMOSPHERE 2021; 284:131315. [PMID: 34323780 DOI: 10.1016/j.chemosphere.2021.131315] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 06/11/2021] [Accepted: 06/20/2021] [Indexed: 06/13/2023]
Abstract
Perchlorate is the main contaminant in surface water and groundwater, and it is of current urgency to remove due to its high water solubility, mobility, and endocrine-disrupting properties. The conversion of perchlorate into harmless chloride ions by using appropriate catalysts is the most promising and effective route to overcome its high activation energy and kinetic stability. Perchlorate is usually reduced in two ways: (1) indirect reduction via oxygen atom transfer (OAT) reaction or (2) hydrodeoxygenation through highly active reducing H atoms. This paper discusses the mechanisms underlying both the OAT reaction catalyzed by homogenous rhenium-oxo complexes or biological Mo-based enzymes and the heterogeneous hydrogenation for perchlorate reduction. Particular emphasis is placed on the factors affecting the catalytic process and the synergy between the (1) and (2) reactions. For completeness, the applicability of different electrolysis devices, electrodes, and bioreactors is also illustrated. Finally, this article gives prospects for the synthesis and application of catalysts in different pathways.
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Affiliation(s)
- Bei Wang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Yunbo Zhai
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China.
| | - Shanhong Li
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Caiting Li
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Yun Zhu
- College of Electrical and Information Engineering, Hunan University, Changsha, 410082, China
| | - Min Xu
- Chinese Academy for Environmental Planning, Beijing, 100012, China.
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6
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Rai A, Klare JP, Reinke PYA, Englmaier F, Fohrer J, Fedorov R, Taft MH, Chizhov I, Curth U, Plettenburg O, Manstein DJ. Structural and Biochemical Characterization of a Dye-Decolorizing Peroxidase from Dictyostelium discoideum. Int J Mol Sci 2021; 22:ijms22126265. [PMID: 34200865 PMCID: PMC8230527 DOI: 10.3390/ijms22126265] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 05/29/2021] [Accepted: 06/05/2021] [Indexed: 12/23/2022] Open
Abstract
A novel cytoplasmic dye-decolorizing peroxidase from Dictyostelium discoideum was investigated that oxidizes anthraquinone dyes, lignin model compounds, and general peroxidase substrates such as ABTS efficiently. Unlike related enzymes, an aspartate residue replaces the first glycine of the conserved GXXDG motif in Dictyostelium DyPA. In solution, Dictyostelium DyPA exists as a stable dimer with the side chain of Asp146 contributing to the stabilization of the dimer interface by extending the hydrogen bond network connecting two monomers. To gain mechanistic insights, we solved the Dictyostelium DyPA structures in the absence of substrate as well as in the presence of potassium cyanide and veratryl alcohol to 1.7, 1.85, and 1.6 Å resolution, respectively. The active site of Dictyostelium DyPA has a hexa-coordinated heme iron with a histidine residue at the proximal axial position and either an activated oxygen or CN- molecule at the distal axial position. Asp149 is in an optimal conformation to accept a proton from H2O2 during the formation of compound I. Two potential distal solvent channels and a conserved shallow pocket leading to the heme molecule were found in Dictyostelium DyPA. Further, we identified two substrate-binding pockets per monomer in Dictyostelium DyPA at the dimer interface. Long-range electron transfer pathways associated with a hydrogen-bonding network that connects the substrate-binding sites with the heme moiety are described.
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Affiliation(s)
- Amrita Rai
- Institute for Biophysical Chemistry, Hannover Medical School, Fritz Hartmann Centre for Medical Research Carl Neuberg Str. 1, D-30625 Hannover, Germany; (A.R.); (P.Y.A.R.); (M.H.T.); (I.C.); (U.C.)
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Johann P. Klare
- Department of Physics, University of Osnabrueck, Barbarastrasse 7, D-49076 Osnabrück, Germany;
| | - Patrick Y. A. Reinke
- Institute for Biophysical Chemistry, Hannover Medical School, Fritz Hartmann Centre for Medical Research Carl Neuberg Str. 1, D-30625 Hannover, Germany; (A.R.); (P.Y.A.R.); (M.H.T.); (I.C.); (U.C.)
- Division for Structural Biochemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany;
- Center for Free-Electron Laser Science, German Electron Synchrotron (DESY), Notkestr. 85, D-22607 Hamburg, Germany
| | - Felix Englmaier
- Institute of Medicinal Chemistry, Helmholtz Zentrum München (GmbH), German Research Center for Environmental Health, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany; (F.E.); (O.P.)
- Center of Biomolecular Drug Research (BMWZ), Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1b, D-30167 Hannover, Germany;
| | - Jörg Fohrer
- Center of Biomolecular Drug Research (BMWZ), Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1b, D-30167 Hannover, Germany;
- NMR Department of the Department of Chemistry, Technical University Darmstadt, Clemens Schöpf Institute for Organic Chemistry and Biochemistry, Alarich-Weiss-Strasse 4, D-64287 Darmstadt, Germany
| | - Roman Fedorov
- Division for Structural Biochemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany;
| | - Manuel H. Taft
- Institute for Biophysical Chemistry, Hannover Medical School, Fritz Hartmann Centre for Medical Research Carl Neuberg Str. 1, D-30625 Hannover, Germany; (A.R.); (P.Y.A.R.); (M.H.T.); (I.C.); (U.C.)
| | - Igor Chizhov
- Institute for Biophysical Chemistry, Hannover Medical School, Fritz Hartmann Centre for Medical Research Carl Neuberg Str. 1, D-30625 Hannover, Germany; (A.R.); (P.Y.A.R.); (M.H.T.); (I.C.); (U.C.)
- Division for Structural Biochemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany;
| | - Ute Curth
- Institute for Biophysical Chemistry, Hannover Medical School, Fritz Hartmann Centre for Medical Research Carl Neuberg Str. 1, D-30625 Hannover, Germany; (A.R.); (P.Y.A.R.); (M.H.T.); (I.C.); (U.C.)
- Division for Structural Biochemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany;
| | - Oliver Plettenburg
- Institute of Medicinal Chemistry, Helmholtz Zentrum München (GmbH), German Research Center for Environmental Health, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany; (F.E.); (O.P.)
- Center of Biomolecular Drug Research (BMWZ), Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1b, D-30167 Hannover, Germany;
| | - Dietmar J. Manstein
- Institute for Biophysical Chemistry, Hannover Medical School, Fritz Hartmann Centre for Medical Research Carl Neuberg Str. 1, D-30625 Hannover, Germany; (A.R.); (P.Y.A.R.); (M.H.T.); (I.C.); (U.C.)
- Division for Structural Biochemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany;
- RESiST, Cluster of Excellence 2155, Medizinische Hochschule Hannover, D-30625 Hannover, Germany
- Correspondence: ; Tel.: +49-511-5323700
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7
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Ren C, Liu J. Bioinspired Catalytic Reduction of Aqueous Perchlorate by One Single-Metal Site with High Stability against Oxidative Deactivation. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05276] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Changxu Ren
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Jinyong Liu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
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8
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Schmidt D, Serra I, Mlynek G, Pfanzagl V, Hofbauer S, Furtmüller PG, Djinović-Carugo K, Van Doorslaer S, Obinger C. Arresting the Catalytic Arginine in Chlorite Dismutases: Impact on Heme Coordination, Thermal Stability, and Catalysis. Biochemistry 2021; 60:621-634. [PMID: 33586945 PMCID: PMC7931450 DOI: 10.1021/acs.biochem.0c00910] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Chlorite dismutases
(Clds) are heme b-containing
oxidoreductases that can decompose chlorite to chloride and molecular
oxygen. They are divided in two clades that differ in oligomerization,
subunit architecture, and the hydrogen-bonding network of the distal
catalytic arginine, which is proposed to switch between two conformations
during turnover. To understand the impact of the conformational dynamics
of this basic amino acid on heme coordination, structure, and catalysis,
Cld from Cyanothece sp. PCC7425 was used as a model
enzyme. As typical for a clade 2 Cld, its distal arginine 127 is hydrogen-bonded
to glutamine 74. The latter has been exchanged with either glutamate
(Q74E) to arrest R127 in a salt bridge or valine (Q74V) that mirrors
the setting in clade 1 Clds. We present the X-ray crystal structures
of Q74V and Q74E and demonstrate the pH-induced changes in the environment
and coordination of the heme iron by ultraviolet–visible, circular
dichroism, and electron paramagnetic resonance spectroscopies as well
as differential scanning calorimetry. The conformational dynamics
of R127 is shown to have a significant role in heme coordination during
the alkaline transition and in the thermal stability of the heme cavity,
whereas its impact on the catalytic efficiency of chlorite degradation
is relatively small. The findings are discussed with respect to (i)
the flexible loop connecting the N-terminal and C-terminal ferredoxin-like
domains, which differs in clade 1 and clade 2 Clds and carries Q74
in clade 2 proteins, and (ii) the proposed role(s) of the arginine
in catalysis.
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Affiliation(s)
- Daniel Schmidt
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Ilenia Serra
- BIMEF Laboratory, Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium
| | - Georg Mlynek
- Department of Structural and Computational Biology, Max Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria
| | - Vera Pfanzagl
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Stefan Hofbauer
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Paul G Furtmüller
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Kristina Djinović-Carugo
- Department of Structural and Computational Biology, Max Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria.,Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 5, SI-1000 Ljubljana, Slovenia
| | - Sabine Van Doorslaer
- BIMEF Laboratory, Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium
| | - Christian Obinger
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
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9
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Mahor D, Püschmann J, Adema DR, Strampraad MJF, Hagedoorn PL. Unexpected photosensitivity of the well-characterized heme enzyme chlorite dismutase. J Biol Inorg Chem 2020; 25:1129-1138. [PMID: 33113038 PMCID: PMC7665973 DOI: 10.1007/s00775-020-01826-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 10/09/2020] [Indexed: 11/30/2022]
Abstract
Chlorite dismutase is a heme enzyme that catalyzes the conversion of the toxic compound ClO2- (chlorite) to innocuous Cl- and O2. The reaction is a very rare case of enzymatic O-O bond formation, which has sparked the interest to elucidate the reaction mechanism using pre-steady-state kinetics. During stopped-flow experiments, spectroscopic and structural changes of the enzyme were observed in the absence of a substrate in the time range from milliseconds to minutes. These effects are a consequence of illumination with UV-visible light during the stopped-flow experiment. The changes in the UV-visible spectrum in the initial 200 s of the reaction indicate a possible involvement of a ferric superoxide/ferrous oxo or ferric hydroxide intermediate during the photochemical inactivation. Observed EPR spectral changes after 30 min reaction time indicate the loss of the heme and release of iron during the process. During prolonged illumination, the oligomeric state of the enzyme changes from homo-pentameric to monomeric with subsequent protein precipitation. Understanding the effects of UV-visible light illumination induced changes of chlorite dismutase will help us to understand the nature and mechanism of photosensitivity of heme enzymes in general. Furthermore, previously reported stopped-flow data of chlorite dismutase and potentially other heme enzymes will need to be re-evaluated in the context of the photosensitivity. Illumination of recombinantly expressed Azospira oryzae Chlorite dismutase (AoCld) with a high-intensity light source, common in stopped-flow equipment, results in disruption of the bond between FeIII and the axial histidine. This leads to the enzyme losing its heme cofactor and changing its oligomeric state as shown by spectroscopic changes and loss of activity.
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Affiliation(s)
- Durga Mahor
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - Julia Püschmann
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - Diederik R Adema
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - Marc J F Strampraad
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - Peter-Leon Hagedoorn
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands.
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10
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Understanding molecular enzymology of porphyrin-binding α + β barrel proteins - One fold, multiple functions. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1869:140536. [PMID: 32891739 PMCID: PMC7611857 DOI: 10.1016/j.bbapap.2020.140536] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/26/2020] [Accepted: 09/02/2020] [Indexed: 11/24/2022]
Abstract
There is a high functional diversity within the structural superfamily of porphyrin-binding dimeric α + β barrel proteins. In this review we aim to analyze structural constraints of chlorite dismutases, dye-decolorizing peroxidases and coproheme decarboxylases in detail. We identify regions of structural variations within the highly conserved fold, which are most likely crucial for functional specificities. The loop linking the two ferredoxin-like domains within one subunit can be of different sequence lengths and can adopt various structural conformations, consequently defining the shape of the substrate channels and the respective active site architectures. The redox cofactor, heme b or coproheme, is oriented differently in either of the analyzed enzymes. By thoroughly dissecting available structures and discussing all available results in the context of the respective functional mechanisms of each of these redox-active enzymes, we highlight unsolved mechanistic questions in order to spark future research in this field.
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11
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Mahor D, Püschmann J, van den Haak M, Kooij PJ, van den Ouden DLJ, Strampraad MJF, Srour B, Hagedoorn PL. A traffic light enzyme: acetate binding reversibly switches chlorite dismutase from a red- to a green-colored heme protein. J Biol Inorg Chem 2020; 25:609-620. [PMID: 32246282 PMCID: PMC7239840 DOI: 10.1007/s00775-020-01784-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 03/22/2020] [Indexed: 11/28/2022]
Abstract
Abstract Chlorite dismutase is a unique heme enzyme that catalyzes the conversion of chlorite to chloride and molecular oxygen. The enzyme is highly specific for chlorite but has been known to bind several anionic and neutral ligands to the heme iron. In a pH study, the enzyme changed color from red to green in acetate buffer pH 5.0. The cause of this color change was uncovered using UV–visible and EPR spectroscopy. Chlorite dismutase in the presence of acetate showed a change of the UV–visible spectrum: a redshift and hyperchromicity of the Soret band from 391 to 404 nm and a blueshift of the charge transfer band CT1 from 647 to 626 nm. Equilibrium binding titrations with acetate resulted in a dissociation constant of circa 20 mM at pH 5.0 and 5.8. EPR spectroscopy showed that the acetate bound form of the enzyme remained high spin S = 5/2, however with an apparent change of the rhombicity and line broadening of the spectrum. Mutagenesis of the proximal arginine Arg183 to alanine resulted in the loss of the ability to bind acetate. Acetate was discovered as a novel ligand to chlorite dismutase, with evidence of direct binding to the heme iron. The green color is caused by a blueshift of the CT1 band that is characteristic of the high spin ferric state of the enzyme. Any weak field ligand that binds directly to the heme center may show the red to green color change, as was indeed the case for fluoride. Graphic abstract ![]()
Electronic supplementary material The online version of this article (10.1007/s00775-020-01784-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Durga Mahor
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - Julia Püschmann
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - Menno van den Haak
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - Pepijn J Kooij
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - David L J van den Ouden
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - Marc J F Strampraad
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - Batoul Srour
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands.,Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Peter-Leon Hagedoorn
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands.
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12
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Sun SQ, Chen SL. How does Mo-dependent perchlorate reductase work in the decomposition of oxyanions? Dalton Trans 2019; 48:5683-5691. [DOI: 10.1039/c9dt00863b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The mechanisms of Mo-dependent perchlorate reductase (PcrAB)-catalyzed decomposition of perchlorate, bromate, iodate, and nitrate were revealed by density functional calculations.
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Affiliation(s)
- Shuo-Qi Sun
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- China
| | - Shi-Lu Chen
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- China
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13
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Geeraerts Z, Celis AI, Mayfield JA, Lorenz M, Rodgers KR, DuBois JL, Lukat-Rodgers GS. Distinguishing Active Site Characteristics of Chlorite Dismutases with Their Cyanide Complexes. Biochemistry 2018; 57:1501-1516. [PMID: 29406727 PMCID: PMC5849076 DOI: 10.1021/acs.biochem.7b01278] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
O2-evolving chlorite dismutases (Clds) efficiently convert chlorite (ClO2-) to O2 and Cl-. Dechloromonas aromatica Cld ( DaCld) is a highly active chlorite-decomposing homopentameric enzyme, typical of Clds found in perchlorate- and chlorate-respiring bacteria. The Gram-negative, human pathogen Klebsiella pneumoniae contains a homodimeric Cld ( KpCld) that also decomposes ClO2-, albeit with an activity 10-fold lower and a turnover number lower than those of DaCld. The interactions between the distal pocket and heme ligand of the DaCld and KpCld active sites have been probed via kinetic, thermodynamic, and spectroscopic behaviors of their cyanide complexes for insight into active site characteristics that are deterministic for chlorite decomposition. At 4.7 × 10-9 M, the KD for the KpCld-CN- complex is 2 orders of magnitude smaller than that of DaCld-CN- and indicates an affinity for CN- that is greater than that of most heme proteins. The difference in CN- affinity between Kp- and DaClds is predominantly due to differences in koff. The kinetics of binding of cyanide to DaCld, DaCld(R183Q), and KpCld between pH 4 and 8.5 corroborate the importance of distal Arg183 and a p Ka of ∼7 in stabilizing complexes of anionic ligands, including the substrate. The Fe-C stretching and FeCN bending modes of the DaCld-CN- (νFe-C, 441 cm-1; δFeCN, 396 cm-1) and KpCld-CN- (νFe-C, 441 cm-1; δFeCN, 356 cm-1) complexes reveal differences in their FeCN angle, which suggest different distal pocket interactions with their bound cyanide. Conformational differences in their catalytic sites are also reported by the single ferrous KpCld carbonyl complex, which is in contrast to the two conformers observed for DaCld-CO.
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Affiliation(s)
- Zachary Geeraerts
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, USA
| | - Arianna I. Celis
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Jeffery A. Mayfield
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Megan Lorenz
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, USA
| | - Kenton R. Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, USA
| | - Jennifer L. DuBois
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Gudrun S. Lukat-Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, USA
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14
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Kosugi N, Araki T, Fujita J, Tanaka S, Fujiwara T. Growth phenotype analysis of heme synthetic enzymes in a halophilic archaeon, Haloferax volcanii. PLoS One 2017; 12:e0189913. [PMID: 29284023 PMCID: PMC5746218 DOI: 10.1371/journal.pone.0189913] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 12/05/2017] [Indexed: 01/09/2023] Open
Abstract
Halophilic euryarchaea lack many of the genes necessary for the protoporphyrin-dependent heme biosynthesis pathway previously identified in animals and plants. Bioinformatic analysis suggested the presence of two heme biosynthetic processes, an Fe-coproporphyrinogen III (coproheme) decarboxylase (ChdC) pathway and an alternative heme biosynthesis (Ahb) pathway, in Haloferax volcanii. PitA is specific to the halophilic archaea and has a unique molecular structure in which the ChdC domain is joined to the antibiotics biosynthesis monooxygenase (ABM)-like domain by a histidine-rich linker sequence. The pitA gene deletion variant of H. volcanii showed a phenotype with a significant reduction of aerobic growth. Addition of a protoheme complemented the phenotype, supporting the assumption that PitA participates in the aerobic heme biosynthesis. Deletion of the ahbD gene caused a significant reduction of only anaerobic growth by denitrification or dimethylsulfoxide (DMSO) respiration, and the growth was also complemented by addition of a protoheme. The experimental results suggest that the two heme biosynthesis pathways are utilized selectively under aerobic and anaerobic conditions in H. volcanii. The molecular structure and physiological function of PitA are also discussed on the basis of the limited proteolysis and sequence analysis.
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Affiliation(s)
- Naoki Kosugi
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Japan
| | - Takuma Araki
- Department of Environment and Energy Systems, Graduate School of Science and Technology, Shizuoka University, Shizuoka, Japan
| | - Junpei Fujita
- Department of Biological Sciences, Faculty of Science, Shizuoka University, Shizuoka, Japan
| | - Satoru Tanaka
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Japan
| | - Taketomo Fujiwara
- Department of Environment and Energy Systems, Graduate School of Science and Technology, Shizuoka University, Shizuoka, Japan
- * E-mail:
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15
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Geeraerts Z, Rodgers KR, DuBois JL, Lukat-Rodgers GS. Active Sites of O 2-Evolving Chlorite Dismutases Probed by Halides and Hydroxides and New Iron-Ligand Vibrational Correlations. Biochemistry 2017; 56:4509-4524. [PMID: 28758386 DOI: 10.1021/acs.biochem.7b00572] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
O2-evolving chlorite dismutases (Clds) fall into two subfamilies, which efficiently convert ClO2- to O2 and Cl-. The Cld from Dechloromonas aromatica (DaCld) represents the chlorite-decomposing homopentameric enzymes found in perchlorate- and chlorate-respiring bacteria. The Cld from the Gram-negative human pathogen Klebsiella pneumoniae (KpCld) is representative of the second subfamily, comprising homodimeric enzymes having truncated N-termini. Here steric and nonbonding properties of the DaCld and KpCld active sites have been probed via kinetic, thermodynamic, and spectroscopic behaviors of their fluorides, chlorides, and hydroxides. Cooperative binding of Cl- to KpCld drives formation of a hexacoordinate, high-spin aqua heme, whereas DaCld remains pentacoordinate and high-spin under analogous conditions. Fluoride coordinates to the heme iron in KpCld and DaCld, exhibiting ν(FeIII-F) bands at 385 and 390 cm-1, respectively. Correlation of these frequencies with their CT1 energies reveals strong H-bond donation to the F- ligand, indicating that atoms directly coordinated to heme iron are accessible to distal H-bond donation. New vibrational frequency correlations between either ν(FeIII-F) or ν(FeIII-OH) and ν(FeII-His) of Clds and other heme proteins are reported. These correlations orthogonalize proximal and distal effects on the bonding between iron and exogenous π-donor ligands. The axial Fe-X vibrations and the relationships between them illuminate both similarities and differences in the H-bonding and electrostatic properties of the distal and proximal heme environments in pentameric and dimeric Clds. Moreover, they provide general insight into the structural basis of reactivity toward substrates in heme-dependent enzymes and their mechanistic intermediates, especially those containing the ferryl moiety.
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Affiliation(s)
- Zachary Geeraerts
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58102, United States
| | - Kenton R Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58102, United States
| | - Jennifer L DuBois
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59715, United States
| | - Gudrun S Lukat-Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58102, United States
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16
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Johnson RJ, Folwell BD, Wirekoh A, Frenzel M, Skovhus TL. Reservoir Souring – Latest developments for application and mitigation. J Biotechnol 2017; 256:57-67. [DOI: 10.1016/j.jbiotec.2017.04.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/31/2017] [Accepted: 04/03/2017] [Indexed: 01/29/2023]
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17
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18
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Hofbauer S, Mlynek G, Milazzo L, Pühringer D, Maresch D, Schaffner I, Furtmüller PG, Smulevich G, Djinović-Carugo K, Obinger C. Hydrogen peroxide-mediated conversion of coproheme to heme b by HemQ-lessons from the first crystal structure and kinetic studies. FEBS J 2016; 283:4386-4401. [PMID: 27758026 PMCID: PMC5157759 DOI: 10.1111/febs.13930] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/11/2016] [Accepted: 10/17/2016] [Indexed: 11/30/2022]
Abstract
Heme biosynthesis in Gram-positive bacteria follows a recently described coproporphyrin-dependent pathway with HemQ catalyzing the decarboxylation of coproheme to heme b. Here we present the first crystal structure of a HemQ (homopentameric coproheme-HemQ from Listeria monocytogenes) at 1.69 Å resolution and the conversion of coproheme to heme b followed by UV-vis and resonance Raman spectroscopy as well as mass spectrometry. The ferric five-coordinated coproheme iron of HemQ is weakly bound by a neutral proximal histidine H174. In the crystal structure of the resting state, the distal Q187 (conserved in Firmicutes HemQ) is H-bonded with propionate p2 and the hydrophobic distal cavity lacks solvent water molecules. Two H2 O2 molecules are shown to be necessary for decarboxylation of the propionates p2 and p4, thereby forming the corresponding vinyl groups of heme b. The overall reaction is relatively slow (kcat /KM = 1.8 × 102 m-1 ·s-1 at pH 7.0) and occurs in a stepwise manner with a three-propionate intermediate. We present the noncovalent interactions between coproheme and the protein and propose a two-step reaction mechanism. Furthermore, the structure of coproheme-HemQ is compared to that of the phylogenetically related heme b-containing chlorite dismutases. DATABASE Structural data are available in the PDB under the accession number 5LOQ.
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Affiliation(s)
- Stefan Hofbauer
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Austria
| | - Georg Mlynek
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Austria
| | - Lisa Milazzo
- Dipartimento di Chimica 'Ugo Schiff', Università di Firenze, Sesto Fiorentino (FI), Italy
| | - Dominic Pühringer
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Austria.,Division of Biochemistry, Department of Chemistry, BOKU - University of Natural Resources and Life Sciences, Vienna, Austria
| | - Daniel Maresch
- Division of Biochemistry, Department of Chemistry, BOKU - University of Natural Resources and Life Sciences, Vienna, Austria
| | - Irene Schaffner
- Division of Biochemistry, Department of Chemistry, BOKU - University of Natural Resources and Life Sciences, Vienna, Austria
| | - Paul G Furtmüller
- Division of Biochemistry, Department of Chemistry, BOKU - University of Natural Resources and Life Sciences, Vienna, Austria
| | - Giulietta Smulevich
- Dipartimento di Chimica 'Ugo Schiff', Università di Firenze, Sesto Fiorentino (FI), Italy
| | - Kristina Djinović-Carugo
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Austria.,Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Slovenia
| | - Christian Obinger
- Division of Biochemistry, Department of Chemistry, BOKU - University of Natural Resources and Life Sciences, Vienna, Austria
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19
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Hofbauer S, Dalla Sega M, Scheiblbrandner S, Jandova Z, Schaffner I, Mlynek G, Djinović-Carugo K, Battistuzzi G, Furtmüller PG, Oostenbrink C, Obinger C. Chemistry and Molecular Dynamics Simulations of Heme b-HemQ and Coproheme-HemQ. Biochemistry 2016; 55:5398-412. [PMID: 27599156 PMCID: PMC5041162 DOI: 10.1021/acs.biochem.6b00701] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recently, a novel pathway for heme b biosynthesis in Gram-positive bacteria has been proposed. The final poorly understood step is catalyzed by an enzyme called HemQ and includes two decarboxylation reactions leading from coproheme to heme b. Coproheme has been suggested to act as both substrate and redox active cofactor in this reaction. In the study presented here, we focus on HemQs from Listeria monocytogenes (LmHemQ) and Staphylococcus aureus (SaHemQ) recombinantly produced as apoproteins in Escherichia coli. We demonstrate the rapid and two-phase uptake of coproheme by both apo forms and the significant differences in thermal stability of the apo forms, coproheme-HemQ and heme b-HemQ. Reduction of ferric high-spin coproheme-HemQ to the ferrous form is shown to be enthalpically favored but entropically disfavored with standard reduction potentials of -205 ± 3 mV for LmHemQ and -207 ± 3 mV for SaHemQ versus the standard hydrogen electrode at pH 7.0. Redox thermodynamics suggests the presence of a pronounced H-bonding network and restricted solvent mobility in the heme cavity. Binding of cyanide to the sixth coproheme position is monophasic but relatively slow (∼1 × 10(4) M(-1) s(-1)). On the basis of the available structures of apo-HemQ and modeling of both loaded forms, molecular dynamics simulation allowed analysis of the interaction of coproheme and heme b with the protein as well as the role of the flexibility at the proximal heme cavity and the substrate access channel for coproheme binding and heme b release. Obtained data are discussed with respect to the proposed function of HemQ in monoderm bacteria.
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Affiliation(s)
- Stefan Hofbauer
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna , A-1030 Vienna, Austria
| | - Marco Dalla Sega
- Department of Material Sciences and Process Engineering, Institute of Molecular Modeling and Simulation, BOKU-University of Natural Resources and Life Sciences , A-1190 Vienna, Austria
| | - Stefan Scheiblbrandner
- Department of Food Science and Technology, Food Biotechnology Laboratory, BOKU-University of Natural Resources and Life Sciences , A-1190 Vienna, Austria
| | - Zuzana Jandova
- Department of Material Sciences and Process Engineering, Institute of Molecular Modeling and Simulation, BOKU-University of Natural Resources and Life Sciences , A-1190 Vienna, Austria
| | - Irene Schaffner
- Department of Chemistry, Division of Biochemistry, VIBT-Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences , A-1190 Vienna, Austria
| | - Georg Mlynek
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna , A-1030 Vienna, Austria
| | - Kristina Djinović-Carugo
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna , A-1030 Vienna, Austria.,Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana , 1000 Ljubljana, Slovenia
| | - Gianantonio Battistuzzi
- Department of Chemistry and Geology, University of Modena and Reggio Emilia , 41125 Modena, Italy
| | - Paul G Furtmüller
- Department of Chemistry, Division of Biochemistry, VIBT-Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences , A-1190 Vienna, Austria
| | - Chris Oostenbrink
- Department of Material Sciences and Process Engineering, Institute of Molecular Modeling and Simulation, BOKU-University of Natural Resources and Life Sciences , A-1190 Vienna, Austria
| | - Christian Obinger
- Department of Chemistry, Division of Biochemistry, VIBT-Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences , A-1190 Vienna, Austria
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20
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Liu J, Han M, Wu D, Chen X, Choe JK, Werth CJ, Strathmann TJ. A New Bioinspired Perchlorate Reduction Catalyst with Significantly Enhanced Stability via Rational Tuning of Rhenium Coordination Chemistry and Heterogeneous Reaction Pathway. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:5874-5881. [PMID: 27182602 DOI: 10.1021/acs.est.6b00886] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Rapid reduction of aqueous ClO4(-) to Cl(-) by H2 has been realized by a heterogeneous Re(hoz)2-Pd/C catalyst integrating Re(O)(hoz)2Cl complex (hoz = oxazolinyl-phenolato bidentate ligand) and Pd nanoparticles on carbon support, but ClOx(-) intermediates formed during reactions with concentrated ClO4(-) promote irreversible Re complex decomposition and catalyst deactivation. The original catalyst design mimics the microbial ClO4(-) reductase, which integrates Mo(MGD)2 complex (MGD = molybdopterin guanine dinucleotide) for oxygen atom transfer (OAT). Perchlorate-reducing microorganisms employ a separate enzyme, chlorite dismutase, to prevent accumulation of the destructive ClO2(-) intermediate. The structural intricacy of MGD ligand and the two-enzyme mechanism for microbial ClO4(-) reduction inspired us to improve catalyst stability by rationally tuning Re ligand structure and adding a ClOx(-) scavenger. Two new Re complexes, Re(O)(htz)2Cl and Re(O)(hoz)(htz)Cl (htz = thiazolinyl-phenolato bidentate ligand), significantly mitigate Re complex decomposition by slightly lowering the OAT activity when immobilized in Pd/C. Further stability enhancement is then obtained by switching the nanoparticles from Pd to Rh, which exhibits high reactivity with ClOx(-) intermediates and thus prevents their deactivating reaction with the Re complex. Compared to Re(hoz)2-Pd/C, the new Re(hoz)(htz)-Rh/C catalyst exhibits similar ClO4(-) reduction activity but superior stability, evidenced by a decrease of Re leaching from 37% to 0.25% and stability of surface Re speciation following the treatment of a concentrated "challenge" solution containing 1000 ppm of ClO4(-). This work demonstrates the pivotal roles of coordination chemistry control and tuning of individual catalyst components for achieving both high activity and stability in environmental catalyst applications.
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Affiliation(s)
- Jinyong Liu
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Department of Civil and Environmental Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Mengwei Han
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Dimao Wu
- Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States
| | - Xi Chen
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Jong Kwon Choe
- Department of Civil and Environmental Engineering, Clarkson University , Potsdam, New York 13699, United States
| | - Charles J Werth
- Department of Civil, Architectural, and Environmental Engineering, University of Texas at Austin , Austin, Texas 78712, United States
| | - Timothy J Strathmann
- Department of Civil and Environmental Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
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21
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Edgcomb VP, Pachiadaki MG, Mara P, Kormas KA, Leadbetter ER, Bernhard JM. Gene expression profiling of microbial activities and interactions in sediments under haloclines of E. Mediterranean deep hypersaline anoxic basins. ISME JOURNAL 2016; 10:2643-2657. [PMID: 27093045 DOI: 10.1038/ismej.2016.58] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 02/11/2016] [Accepted: 03/03/2016] [Indexed: 11/09/2022]
Abstract
Deep-sea hypersaline anoxic basins (DHABs) in the Eastern Mediterranean Sea are considered some of the most polyextreme habitats on Earth. In comparison to microbial activities occurring within the haloclines and brines of these unusual water column habitats near the Mediterranean seafloor, relatively little is known about microbial metabolic activities in the underlying sediments. In addition, it is not known whether activities are shaped by the unique chemistries of the different DHAB brines and whether evidence exists for active microbial eukaryotes in those sediments. Metatranscriptome analysis was applied to sediment samples collected using ROV Jason from underneath the haloclines of Urania, Discovery and L'Atalante DHABs and a control site. We report on expression of genes associated with sulfur and nitrogen cycling, putative osmolyte biosynthetic pathways and ion transporters, trace metal detoxification, selected eukaryotic activities (particularly of fungi), microbe-microbe interactions, and motility in sediments underlying the haloclines of three DHABs. Relative to our control sediment sample collected outside of Urania Basin, microbial communities (including eukaryotes) in the Urania and Discovery DHAB sediments showed upregulation of expressed genes associated with nitrogen transformations, osmolyte biosynthesis, heavy metals resistance and metabolism, eukaryotic organelle functions, and cell-cell interactions. Sediments underlying DHAB haloclines that have cumulative physico-chemical stressors within the limits of tolerance for microoorganisms can therefore be hotspots of activity in the deep Mediterranean Sea.
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Affiliation(s)
- Virginia P Edgcomb
- Department of Geology & Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Maria G Pachiadaki
- Department of Geology & Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Paraskevi Mara
- Department of Chemistry, University of Crete, Heraklion, Greece
| | - Konstantinos A Kormas
- Department of Ichthyology & Aquatic Environment, University of Thessaly, Volos, Greece
| | - Edward R Leadbetter
- Department of Geology & Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Joan M Bernhard
- Department of Geology & Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
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22
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Acharya G, Kaur G, Subramanian S. Evolutionary relationships between heme-binding ferredoxin α + β barrels. BMC Bioinformatics 2016; 17:168. [PMID: 27089923 PMCID: PMC4835899 DOI: 10.1186/s12859-016-1033-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 04/12/2016] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The α + β barrel superfamily of the ferredoxin-like fold consists of a functionally diverse group of evolutionarily related proteins. The barrel architecture of these proteins is formed by either homo-/hetero-dimerization or duplication and fusion of ferredoxin-like domains. Several members of this superfamily bind heme in order to carry out their functions. RESULTS We analyze the heme-binding sites in these proteins as well as their barrel topologies. Our comparative structural analysis of these heme-binding barrels reveals two distinct modes of packing of the ferredoxin-like domains to constitute the α + β barrel, which is typified by the Type-1/IsdG-like and Type-2/OxdA-like proteins, respectively. We examine the heme-binding pockets and explore the versatility of the α + β barrels ability to accommodate heme or heme-related moieties, such as siroheme, in at least three different sites, namely, the mode seen in IsdG/OxdA, Cld/DyP/EfeB/HemQ and siroheme decarboxylase barrels. CONCLUSIONS Our study offers insights into the plausible evolutionary relationships between the two distinct barrel packing topologies and relate the observed heme-binding sites to these topologies.
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Affiliation(s)
- Giriraj Acharya
- CSIR-Institute of Microbial Technology (IMTECH), Sector 39-A, Chandigarh, India
| | - Gurmeet Kaur
- CSIR-Institute of Microbial Technology (IMTECH), Sector 39-A, Chandigarh, India
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23
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From chlorite dismutase towards HemQ - the role of the proximal H-bonding network in haeme binding. Biosci Rep 2016; 36:BSR20150330. [PMID: 26858461 PMCID: PMC4793301 DOI: 10.1042/bsr20150330] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 01/21/2016] [Indexed: 12/31/2022] Open
Abstract
Chlorite dismutase (Cld) and HemQ are structurally and phylogenetically closely related haeme enzymes differing fundamentally in their enzymatic properties. Clds are able to convert chlorite into chloride and dioxygen, whereas HemQ is proposed to be involved in the haeme b synthesis of Gram-positive bacteria. A striking difference between these protein families concerns the proximal haeme cavity architecture. The pronounced H-bonding network in Cld, which includes the proximal ligand histidine and fully conserved glutamate and lysine residues, is missing in HemQ. In order to understand the functional consequences of this clearly evident difference, specific hydrogen bonds in Cld from 'Candidatus Nitrospira defluvii' (NdCld) were disrupted by mutagenesis. The resulting variants (E210A and K141E) were analysed by a broad set of spectroscopic (UV-vis, EPR and resonance Raman), calorimetric and kinetic methods. It is demonstrated that the haeme cavity architecture in these protein families is very susceptible to modification at the proximal site. The observed consequences of such structural variations include a significant decrease in thermal stability and also affinity between haeme b and the protein, a partial collapse of the distal cavity accompanied by an increased percentage of low-spin state for the E210A variant, lowered enzymatic activity concomitant with higher susceptibility to self-inactivation. The high-spin (HS) ligand fluoride is shown to exhibit a stabilizing effect and partially restore wild-type Cld structure and function. The data are discussed with respect to known structure-function relationships of Clds and the proposed function of HemQ as a coprohaeme decarboxylase in the last step of haeme biosynthesis in Firmicutes and Actinobacteria.
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24
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De Schutter A, Correia HD, Freire DM, Rivas MG, Rizzi A, Santos-Silva T, González PJ, Van Doorslaer S. Ligand Binding to Chlorite Dismutase from Magnetospirillum sp. J Phys Chem B 2015; 119:13859-69. [PMID: 26287794 DOI: 10.1021/acs.jpcb.5b04141] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chlorite dismutase (Cld) catalyzes the reduction of chlorite to chloride and dioxygen. Here, the ligand binding to Cld of Magnetospirillum sp. (MaCld) is investigated with X-ray crystallography and electron paramagnetic resonance (EPR). EPR reveals a large heterogeneity in the structure of wild-type MaCld, showing a variety of low- and high-spin ferric heme forms. Addition of an axial ligand, such as azide or imidazole, removes this heterogeneity almost entirely. This is in line with the two high resolution crystal structures of MaCld obtained in the presence of azide and thiocyanate that show the coordination of the ligands to the heme iron. The crystal structure of the MaCld-azide complex reveals a single well-defined orientation of the azide molecule in the heme pocket. EPR shows, however, a pH-dependent heme structure, probably due to acid-base transitions of the surrounding amino-acid residues stabilizing azide. For the azide and imidazole complex of MaCld, the hyperfine and nuclear quadrupole interactions with the close-by (14)N and (1)H nuclei are determined using pulsed EPR. These values are compared to the corresponding data for the low-spin forms observed in the ferric wild-type MaCld and to existing EPR data on azide and imidazole complexes of other heme proteins.
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Affiliation(s)
- Amy De Schutter
- BIMEF Laboratory, Department of Physics, University of Antwerp , Universiteitsplein 1, B-2610 Wilrijk, Belgium
| | - Hugo D Correia
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , 2829-516 Caparica, Portugal
| | - Diana M Freire
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , 2829-516 Caparica, Portugal
| | - María G Rivas
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral , Ciudad Universitaria, Paraje El Pozo, S3000ZAA Santa Fe, Argentina
| | - Alberto Rizzi
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral , Ciudad Universitaria, Paraje El Pozo, S3000ZAA Santa Fe, Argentina
| | - Teresa Santos-Silva
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , 2829-516 Caparica, Portugal
| | - Pablo J González
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral , Ciudad Universitaria, Paraje El Pozo, S3000ZAA Santa Fe, Argentina
| | - Sabine Van Doorslaer
- BIMEF Laboratory, Department of Physics, University of Antwerp , Universiteitsplein 1, B-2610 Wilrijk, Belgium
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25
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Freire DM, Rivas MG, Dias AM, Lopes AT, Costa C, Santos-Silva T, Van Doorslaer S, González PJ. The homopentameric chlorite dismutase from Magnetospirillum sp. J Inorg Biochem 2015. [PMID: 26218477 DOI: 10.1016/j.jinorgbio.2015.07.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chlorite dismutase (Cld) is a b-type heme containing enzyme that catalyzes the reduction of chlorite into chloride plus dioxygen. This enzyme has gained attention because it can be used in the development of bioremediation processes, biosensors, and controlled dioxygen production. In the present work, Cld was purified from Magnetospirillum sp. cells cultured anaerobically with acetate/perchlorate until stationary phase. Biochemical, spectroscopic and X-ray crystallography methods showed that Cld from Magnetospirillum sp. is a ~140 kDa homopentamer comprising ~27.8 kDa monomers. Preliminary X-ray crystallography studies confirmed the quaternary structure and the presence of one b-type heme per monomer. The EPR spectroscopic signature of the as-purified Cld samples is affected by the buffer composition used during the purification. Potassium phosphate buffer is the only buffer that affected neither the spectral nor the kinetic properties of Cld. Kinetic studies in solution revealed that Cld from Magnetospirillum sp. decomposes chlorite at high turnover rates with optimal pH6.0. A temperature below 10 °C is required to avoid enzyme inactivation due to cofactor bleaching during turnover, and to achieve full substrate consumption. Cld kinetic parameters were not affected when kinetic assays were performed in the presence of air or under argon atmosphere, but chloride is a weak mixed inhibitor that modifies the EPR signal of as-prepared samples.
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Affiliation(s)
- Diana M Freire
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Maria G Rivas
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal; Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Ciudad Universitaria, Paraje El Pozo, S3000ZAA Santa Fe, Argentina
| | - André M Dias
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Ana T Lopes
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Cristina Costa
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Teresa Santos-Silva
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Sabine Van Doorslaer
- Department of Physics, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium.
| | - Pablo J González
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal; Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Ciudad Universitaria, Paraje El Pozo, S3000ZAA Santa Fe, Argentina.
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26
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Celis AI, DuBois JL. Substrate, product, and cofactor: The extraordinarily flexible relationship between the CDE superfamily and heme. Arch Biochem Biophys 2015; 574:3-17. [PMID: 25778630 PMCID: PMC4414885 DOI: 10.1016/j.abb.2015.03.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 03/06/2015] [Accepted: 03/08/2015] [Indexed: 12/21/2022]
Abstract
PFam Clan 0032, also known as the CDE superfamily, is a diverse group of at least 20 protein families sharing a common α,β-barrel domain. Of these, six different groups bind heme inside the barrel's interior, using it alternately as a cofactor, substrate, or product. Focusing on these six, an integrated picture of structure, sequence, taxonomy, and mechanism is presented here, detailing how a single structural motif might be able to mediate such an array of functions with one of nature's most important small molecules.
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Affiliation(s)
- Arianna I Celis
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, United States
| | - Jennifer L DuBois
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, United States.
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27
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Hofbauer S, Hagmüller A, Schaffner I, Mlynek G, Krutzler M, Stadlmayr G, Pirker KF, Obinger C, Daims H, Djinović-Carugo K, Furtmüller PG. Structure and heme-binding properties of HemQ (chlorite dismutase-like protein) from Listeria monocytogenes. Arch Biochem Biophys 2015; 574:36-48. [PMID: 25602700 PMCID: PMC4420033 DOI: 10.1016/j.abb.2015.01.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 01/07/2015] [Accepted: 01/09/2015] [Indexed: 11/17/2022]
Abstract
Chlorite dismutase-like proteins are structurally closely related to functional chlorite dismutases which are heme b-dependent oxidoreductases capable of reducing chlorite to chloride with simultaneous production of dioxygen. Chlorite dismutase-like proteins are incapable of performing this reaction and their biological role is still under discussion. Recently, members of this large protein family were shown to be involved in heme biosynthesis in Gram-positive bacteria, and thus the protein was renamed HemQ in these organisms. In the present work the structural and heme binding properties of the chlorite dismutase-like protein from the Gram-positive pathogen Listeria monocytogenes (LmCld) were analyzed in order to evaluate its potential role as a regulatory heme sensing protein. The homopentameric crystal structure (2.0Å) shows high similarity to chlorite-degrading chlorite dismutases with an important difference in the structure of the putative substrate and heme entrance channel. In solution LmCld is a stable hexamer able to bind the low-spin ligand cyanide. Heme binding is reversible with KD-values determined to be 7.2μM (circular dichroism spectroscopy) and 16.8μM (isothermal titration calorimetry) at pH 7.0. Both acidic and alkaline conditions promote heme release. Presented biochemical and structural data reveal that the chlorite dismutase-like protein from L. monocytogenes could act as a potential regulatory heme sensing and storage protein within heme biosynthesis.
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Affiliation(s)
- Stefan Hofbauer
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria; Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria
| | - Andreas Hagmüller
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria
| | - Irene Schaffner
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Georg Mlynek
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria
| | - Michael Krutzler
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria; Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria
| | - Gerhard Stadlmayr
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Katharina F Pirker
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Christian Obinger
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Holger Daims
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, A-1090 Vienna, Austria
| | - Kristina Djinović-Carugo
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria; Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia.
| | - Paul G Furtmüller
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
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28
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Schaffner I, Hofbauer S, Krutzler M, Pirker KF, Bellei M, Stadlmayr G, Mlynek G, Djinovic-Carugo K, Battistuzzi G, Furtmüller PG, Daims H, Obinger C. Dimeric chlorite dismutase from the nitrogen-fixing cyanobacterium Cyanothece sp. PCC7425. Mol Microbiol 2015; 96:1053-68. [PMID: 25732258 PMCID: PMC4973843 DOI: 10.1111/mmi.12989] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2015] [Indexed: 11/28/2022]
Abstract
It is demonstrated that cyanobacteria (both azotrophic and non-azotrophic) contain heme b oxidoreductases that can convert chlorite to chloride and molecular oxygen (incorrectly denominated chlorite 'dismutase', Cld). Beside the water-splitting manganese complex of photosystem II, this metalloenzyme is the second known enzyme that catalyses the formation of a covalent oxygen-oxygen bond. All cyanobacterial Clds have a truncated N-terminus and are dimeric (i.e. clade 2) proteins. As model protein, Cld from Cyanothece sp. PCC7425 (CCld) was recombinantly produced in Escherichia coli and shown to efficiently degrade chlorite with an activity optimum at pH 5.0 [kcat 1144 ± 23.8 s(-1), KM 162 ± 10.0 μM, catalytic efficiency (7.1 ± 0.6) × 10(6) M(-1) s(-1)]. The resting ferric high-spin axially symmetric heme enzyme has a standard reduction potential of the Fe(III)/Fe(II) couple of -126 ± 1.9 mV at pH 7.0. Cyanide mediates the formation of a low-spin complex with k(on) = (1.6 ± 0.1) × 10(5) M(-1) s(-1) and k(off) = 1.4 ± 2.9 s(-1) (KD ∼ 8.6 μM). Both, thermal and chemical unfolding follows a non-two-state unfolding pathway with the first transition being related to the release of the prosthetic group. The obtained data are discussed with respect to known structure-function relationships of Clds. We ask for the physiological substrate and putative function of these O2 -producing proteins in (nitrogen-fixing) cyanobacteria.
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Affiliation(s)
- Irene Schaffner
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
| | - Stefan Hofbauer
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria.,Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Michael Krutzler
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
| | - Katharina F Pirker
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
| | - Marzia Bellei
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125, Modena, Italy
| | - Gerhard Stadlmayr
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
| | - Georg Mlynek
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Kristina Djinovic-Carugo
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria.,Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Gianantonio Battistuzzi
- Department of Chemistry and Geology, University of Modena and Reggio Emilia, 41125, Modena, Italy
| | - Paul G Furtmüller
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
| | - Holger Daims
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Christian Obinger
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
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29
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Thomsen M, Tuukkanen A, Dickerhoff J, Palm GJ, Kratzat H, Svergun DI, Weisz K, Bornscheuer UT, Hinrichs W. Structure and catalytic mechanism of the evolutionarily unique bacterial chalcone isomerase. ACTA ACUST UNITED AC 2015; 71:907-17. [PMID: 25849401 DOI: 10.1107/s1399004715001935] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 01/29/2015] [Indexed: 11/10/2022]
Abstract
Flavonoids represent a large class of secondary metabolites produced by plants. These polyphenolic compounds are well known for their antioxidative abilities, are antimicrobial phytoalexins responsible for flower pigmentation to attract pollinators and, in addition to other properties, are also specific bacterial regulators governing the expression of Rhizobium genes involved in root nodulation (Firmin et al., 1986). The bacterial chalcone isomerase (CHI) from Eubacterium ramulus catalyses the first step in a flavanone-degradation pathway by ring opening of (2S)-naringenin to form naringenin chalcone. The structural biology and enzymology of plant CHIs have been well documented, whereas the existence of bacterial CHIs has only recently been elucidated. This first determination of the structure of a bacterial CHI provides detailed structural insights into the key step of the flavonoid-degradation pathway. The active site could be confirmed by co-crystallization with the substrate (2S)-naringenin. The stereochemistry of the proposed mechanism of the isomerase reaction was verified by specific (1)H/(2)H isotope exchange observed by (1)H NMR experiments and was further supported by mutagenesis studies. The active site is shielded by a flexible lid, the varying structure of which could be modelled in different states of the catalytic cycle using small-angle X-ray scattering data together with the crystallographic structures. Comparison of bacterial CHI with the plant enzyme from Medicago sativa reveals that they have unrelated folds, suggesting that the enzyme activity evolved convergently from different ancestor proteins. Despite the lack of any functional relationship, the tertiary structure of the bacterial CHI shows similarities to the ferredoxin-like fold of a chlorite dismutase and the stress-related protein SP1.
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Affiliation(s)
- Maren Thomsen
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17489 Greifswald, Germany
| | - Anne Tuukkanen
- EMBL, c/o DESY, Notkestrasse 85, Gebäude 25A, 22603 Hamburg, Germany
| | - Jonathan Dickerhoff
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17489 Greifswald, Germany
| | - Gottfried J Palm
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17489 Greifswald, Germany
| | - Hanna Kratzat
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17489 Greifswald, Germany
| | - Dmitri I Svergun
- EMBL, c/o DESY, Notkestrasse 85, Gebäude 25A, 22603 Hamburg, Germany
| | - Klaus Weisz
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17489 Greifswald, Germany
| | - Uwe T Bornscheuer
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17489 Greifswald, Germany
| | - Winfried Hinrichs
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17489 Greifswald, Germany
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30
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Schaffner I, Hofbauer S, Krutzler M, Pirker KF, Furtmüller PG, Obinger C. Mechanism of chlorite degradation to chloride and dioxygen by the enzyme chlorite dismutase. Arch Biochem Biophys 2015; 574:18-26. [PMID: 25748001 DOI: 10.1016/j.abb.2015.02.031] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 02/19/2015] [Accepted: 02/25/2015] [Indexed: 11/18/2022]
Abstract
Heme b containing chlorite dismutase (Cld) catalyses the conversion of chlorite to chloride and dioxygen which includes an unusual OO bond formation. This review summarizes our knowledge about the interaction of chlorite with heme enzymes and introduces the biological role, phylogeny and structure of functional chlorite dismutases with differences in overall structure and subunit architecture. The paper sums up the available experimental and computational studies on chlorite degradation by water soluble porphyrin complexes as well as a model based on the active site of Cld. Finally, it reports the available biochemical and biophysical data of Clds from different organisms which allow the presentation of a general reaction mechanism. It includes binding of chlorite to ferric Cld followed by subsequent heterolytic OCl bond cleavage leading to the formation of Compound I and hypochlorite, which finally recombine for production of chloride and O2. The role of the Cld-typical distal arginine in catalysis is discussed together with the pH dependence of the reaction and the role of transiently produced hypochlorite in irreversible inactivation of the enzyme.
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Affiliation(s)
- Irene Schaffner
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Stefan Hofbauer
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria; Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria
| | - Michael Krutzler
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Katharina F Pirker
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Paul G Furtmüller
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Christian Obinger
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
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31
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Abstract
O₂-generating reactions are exceedingly rare in biology and difficult to mimic synthetically. Perchlorate-respiring bacteria enzymatically detoxify chlorite (ClO₂(-) ), the end product of the perchlorate (ClO(4)(-) ) respiratory pathway, by rapidly converting it to dioxygen (O₂) and chloride (Cl(-)). This reaction is catalyzed by a heme-containing protein, called chlorite dismutase (Cld), which bears no structural or sequence relationships with known peroxidases or other heme proteins and is part of a large family of proteins with more than one biochemical function. The original assumptions from the 1990s that perchlorate is not a natural product and that perchlorate respiration might be confined to a taxonomically narrow group of species have been called into question, as have the roles of perchlorate respiration and Cld-mediated reactions in the global biogeochemical cycle of chlorine. In this chapter, the chemistry and biochemistry of Cld-mediated O₂generation, as well as the biological and geochemical context of this extraordinary reaction, are described.
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Affiliation(s)
- Jennifer L DuBois
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA,
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32
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Celis AI, Geeraerts Z, Ngmenterebo D, Machovina MM, Kurker RC, Rajakumar K, Ivancich A, Rodgers KR, Lukat-Rodgers GS, DuBois JL. A dimeric chlorite dismutase exhibits O2-generating activity and acts as a chlorite antioxidant in Klebsiella pneumoniae MGH 78578. Biochemistry 2014; 54:434-46. [PMID: 25437493 PMCID: PMC4303309 DOI: 10.1021/bi501184c] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
Chlorite
dismutases (Clds) convert chlorite to O2 and
Cl–, stabilizing heme in the presence of strong
oxidants and forming the O=O bond with high efficiency. The
enzyme from the pathogen Klebsiella pneumoniae (KpCld) represents a subfamily of Clds that share most of
their active site structure with efficient O2-producing
Clds, even though they have a truncated monomeric structure, exist
as a dimer rather than a pentamer, and come from Gram-negative bacteria
without a known need to degrade chlorite. We hypothesized that KpCld, like others in its subfamily, should be able to make
O2 and may serve an in vivo antioxidant
function. Here, it is demonstrated that it degrades chlorite with
limited turnovers relative to the respiratory Clds, in part because
of the loss of hypochlorous acid from the active site and destruction
of the heme. The observation of hypochlorous acid, the expected leaving
group accompanying transfer of an oxygen atom to the ferric heme,
is consistent with the more open, solvent-exposed heme environment
predicted by spectroscopic measurements and inferred from the crystal
structures of related proteins. KpCld is more susceptible
to oxidative degradation under turnover conditions than the well-characterized
Clds associated with perchlorate respiration. However, wild-type K. pneumoniae has a significant growth advantage in the
presence of chlorate relative to a Δcld knockout
strain, specifically under nitrate-respiring conditions. This suggests
that a physiological function of KpCld may be detoxification
of endogenously produced chlorite.
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Affiliation(s)
- Arianna I Celis
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59715, United States
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Sündermann A, Reif MM, Hofbauer S, Obinger C, Oostenbrink C. Investigation of ion binding in chlorite dismutases by means of molecular dynamics simulations. Biochemistry 2014; 53:4869-79. [PMID: 24988286 PMCID: PMC4116397 DOI: 10.1021/bi500467h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
![]()
Chlorite
dismutases are prokaryotic heme b oxidoreductases
that convert chlorite to chloride and dioxygen. It has been postulated
that during turnover hypochlorite is formed transiently, which might
be responsible for the observed irreversible inactivation of these
iron proteins. The only charged distal residue in the heme cavity
is a conserved and mobile arginine, but its role in catalysis and
inactivation is not fully understood. In the present study, the pentameric
chlorite dismutase (Cld) from the bacterium Candidatus Nitrospira
defluvii was probed for binding of the low spin ligand cyanide,
the substrate chlorite, and the intermediate hypochlorite. Simulations
were performed with the enzyme in the ferrous, ferric, and compound
I state. Additionally, the variant R173A was studied. We report the
parametrization for the GROMOS force field of the anions ClO–, ClO2–, ClO3–, and ClO4– and describe spontaneous
binding, unbinding, and rebinding events of chlorite and hypochlorite,
as well as the dynamics of the conformations of Arg173 during simulations.
The findings suggest that (i) chlorite binding to ferric NdCld occurs
spontaneously and (ii) that Arg173 is important for recognition and
to impair hypochlorite leakage from the reaction sphere. The simulation
data is discussed in comparison with experimental data on catalysis
and inhibition of chlorite dismutase.
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Affiliation(s)
- Axel Sündermann
- Department of Material Sciences and Process Engineering, Institute of Molecular Modeling and Simulation, University of Natural Resources and Life Sciences Vienna , Muthgasse 18, A-1190 Vienna, Austria
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Hofbauer S, Gruber C, Pirker KF, Sündermann A, Schaffner I, Jakopitsch C, Oostenbrink C, Furtmüller PG, Obinger C. Transiently produced hypochlorite is responsible for the irreversible inhibition of chlorite dismutase. Biochemistry 2014; 53:3145-57. [PMID: 24754261 PMCID: PMC4029776 DOI: 10.1021/bi500401k] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Chlorite dismutases (Clds) are heme b-containing prokaryotic oxidoreductases that catalyze the reduction of chlorite to chloride with the concomitant release of molecular oxygen. Over time, they are irreversibly inactivated. To elucidate the mechanism of inactivation and investigate the role of the postulated intermediate hypochlorite, the pentameric chlorite dismutase of "Candidatus Nitrospira defluvii" (NdCld) and two variants (having the conserved distal arginine 173 exchanged with alanine and lysine) were recombinantly produced in Escherichia coli. Exchange of the distal arginine boosts the extent of irreversible inactivation. In the presence of the hypochlorite traps methionine, monochlorodimedone, and 2-[6-(4-aminophenoxy)-3-oxo-3H-xanthen-9-yl]benzoic acid, the extent of chlorite degradation and release of molecular oxygen is significantly increased, whereas heme bleaching and oxidative modifications of the protein are suppressed. Among other modifications, hypochlorite-mediated formation of chlorinated tyrosines is demonstrated by mass spectrometry. The data obtained were analyzed with respect to the proposed reaction mechanism for chlorite degradation and its dependence on pH. We discuss the role of distal Arg173 by keeping hypochlorite in the reaction sphere for O-O bond formation.
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Affiliation(s)
- Stefan Hofbauer
- Department of Chemistry, Division of Biochemistry, VIBT-Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences , A-1190 Vienna, Austria
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35
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Affiliation(s)
- Luisa B. Maia
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - José J. G. Moura
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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36
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Hofbauer S, Schaffner I, Furtmüller PG, Obinger C. Chlorite dismutases - a heme enzyme family for use in bioremediation and generation of molecular oxygen. Biotechnol J 2014; 9:461-73. [PMID: 24519858 PMCID: PMC4162996 DOI: 10.1002/biot.201300210] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 12/06/2013] [Accepted: 01/14/2014] [Indexed: 11/09/2022]
Abstract
Chlorite is a serious environmental concern, as rising concentrations of this harmful anthropogenic compound have been detected in groundwater, drinking water, and soil. Chlorite dismutases (Clds) are therefore important molecules in bioremediation as Clds catalyze the degradation of chlorite to chloride and molecular oxygen. Clds are heme b-containing oxidoreductases present in numerous bacterial and archaeal phyla. This review presents the phylogeny of functional Clds and Cld-like proteins, and demonstrates the close relationship of this novel enzyme family to the recently discovered dye-decolorizing peroxidases. The available X-ray structures, biophysical and enzymatic properties, as well as a proposed reaction mechanism, are presented and critically discussed. Open questions about structure-function relationships are addressed, including the nature of the catalytically relevant redox and reaction intermediates and the mechanism of inactivation of Clds during turnover. Based on analysis of currently available data, chlorite dismutase from "Candidatus Nitrospira defluvii" is suggested as a model Cld for future application in biotechnology and bioremediation. Additionally, Clds can be used in various applications as local generators of molecular oxygen, a reactivity already exploited by microbes that must perform aerobic metabolic pathways in the absence of molecular oxygen. For biotechnologists in the field of chemical engineering and bioremediation, this review provides the biochemical and biophysical background of the Cld enzyme family as well as critically assesses Cld's technological potential.
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Affiliation(s)
- Stefan Hofbauer
- Department of Chemistry, Division of Biochemistry, Vienna Institute of BioTechnology, BOKU, University of Natural Resources and Life Sciences, Vienna, Austria
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37
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Rai A, Fedorov R, Manstein DJ. Expression, purification and crystallization of a dye-decolourizing peroxidase from Dictyostelium discoideum. Acta Crystallogr F Struct Biol Commun 2014; 70:252-5. [PMID: 24637768 PMCID: PMC3936452 DOI: 10.1107/s2053230x14000545] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 01/09/2014] [Indexed: 11/10/2022] Open
Abstract
Dye-decolourizing peroxidases are haem-containing peroxidases with broad substrate specificity. Using H2O2 as an electron acceptor, they efficiently decolourize various dyes that are of industrial and environmental relevance, such as anthraquninone- and azo-based dyes. In this study, the dye-decolourizing peroxidase DdDyP from Dictyostelium discoideum was overexpressed in Escherichia coli strain Rosetta(DE3)pLysS, purified and crystallized using the vapour-diffusion method. A native crystal diffracted to 1.65 Å resolution and belonged to space group P4(1)2(1)2, with unit-cell parameters a = b = 141.03, c = 95.56 Å, α = β = γ = 90°. The asymmetric unit contains two molecules.
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Affiliation(s)
- Amrita Rai
- Institute for Biophysical Chemistry, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Roman Fedorov
- Institute for Biophysical Chemistry, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Dietmar J. Manstein
- Institute for Biophysical Chemistry, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
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38
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Hofbauer S, Gysel K, Bellei M, Hagmüller A, Schaffner I, Mlynek G, Kostan J, Pirker KF, Daims H, Furtmüller PG, Battistuzzi G, Djinović-Carugo K, Obinger C. Manipulating conserved heme cavity residues of chlorite dismutase: effect on structure, redox chemistry, and reactivity. Biochemistry 2014; 53:77-89. [PMID: 24364531 PMCID: PMC3893830 DOI: 10.1021/bi401042z] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Chlorite dismutases (Clds) are heme b containing
oxidoreductases that convert chlorite to chloride and molecular oxygen.
In order to elucidate the role of conserved heme cavity residues in
the catalysis of this reaction comprehensive mutational and biochemical
analyses of Cld from “Candidatus Nitrospira
defluvii” (NdCld) were performed. Particularly, point mutations
of the cavity-forming residues R173, K141, W145, W146, and E210 were
performed. The effect of manipulation in 12 single and double mutants
was probed by UV–vis spectroscopy, spectroelectrochemistry,
pre-steady-state and steady-state kinetics, and X-ray crystallography.
Resulting biochemical data are discussed with respect to the known
crystal structure of wild-type NdCld and the variants R173A and R173K
as well as the structures of R173E, W145V, W145F, and the R173Q/W146Y
solved in this work. The findings allow a critical analysis of the
role of these heme cavity residues in the reaction mechanism of chlorite
degradation that is proposed to involve hypohalous acid as transient
intermediate and formation of an O=O bond. The distal R173
is shown to be important (but not fully essential) for the reaction
with chlorite, and, upon addition of cyanide, it acts as a proton
acceptor in the formation of the resulting low-spin complex. The proximal
H-bonding network including K141-E210-H160 keeps the enzyme in its
ferric (E°′ = −113 mV) and mainly
five-coordinated high-spin state and is very susceptible to perturbation.
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Affiliation(s)
- Stefan Hofbauer
- Department of Chemistry, Division of Biochemistry, VIBT - Vienna Institute of BioTechnology, BOKU - University of Natural Resources and Life Sciences , A-1190 Vienna, Austria
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39
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Sun S, Li ZS, Chen SL. A dominant homolytic O-Cl bond cleavage with low-spin triplet-state Fe(IV)=O formed is revealed in the mechanism of heme-dependent chlorite dismutase. Dalton Trans 2013; 43:973-81. [PMID: 24162174 DOI: 10.1039/c3dt52171k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chlorite dismutase (Cld) is a heme-dependent enzyme that catalyzes the decomposition of toxic chlorite (ClO2(-)) into innocuous chloride and O2. In this paper, using the hybrid B3LYP density functional theory (DFT) method including dispersion interactions, the Cld reaction mechanism has been studied with a chemical model constructed on the X-ray crystal structure. The calculations indicate that the reaction proceeds along a stepwise pathway in the doublet state, i.e. a homolytic O-Cl bond cleavage of the substrate leading to an O-Fe(heme) species and a ClO˙ radical, followed by a rebinding O-O bond formation between them. The O-Fe(heme) species is demonstrated to be a low-spin triplet-state Fe(IV)=O diradicaloid. A low-spin singlet-state Fe(IV)=O is much less stable than the former, with an energy difference of 9.2 kcal mol(-1). The O-Cl bond cleavage is rate-limiting with a barrier of 10.6 kcal mol(-1), in good agreement with the experimental reaction rate of 2.0 × 10(5) s(-1). Furthermore, a heterolytic O-Cl bond dissociation in the initial step is shown to be unreachable, which ensures the high efficiency of the Cld enzyme by avoiding the generation of chlorate byproduct observed in the reactions of synthetic Fe porphyrins. Also, the pathways in the quartet and sextet states are unfavorable for the Cld reaction. The present results reveal a detailed mechanism III (defined in the text) including an interesting di-radical intermediate composed of a low-spin triplet-state Fe(IV)=O and a ClO˙ radical. Compared to a competitive heterolytic Cl-O cleavage in synthetic Fe porphyrins, the revelation of the domination of homolysis in Cld indicates not only the high efficiency of enzyme, but also the sensitivity of a heme and the significance of the enzymatic active-site surroundings (the His170 and Arg183 residues in the present case), which gives more insights into heme chemistry.
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Affiliation(s)
- Shuo Sun
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry, Beijing Institute of Technology, Beijing 100081, China.
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40
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Mayfield JA, Blanc B, Rodgers KR, Lukat-Rodgers GS, DuBois JL. Peroxidase-type reactions suggest a heterolytic/nucleophilic O-O joining mechanism in the heme-dependent chlorite dismutase. Biochemistry 2013; 52:6982-94. [PMID: 24001266 DOI: 10.1021/bi4005599] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heme-containing chlorite dismutases (Clds) catalyze a highly unusual O-O bond-forming reaction. The O-O cleaving reactions of hydrogen peroxide and peracetic acid (PAA) with the Cld from Dechloromonas aromatica (DaCld) were studied to better understand the Cl-O cleavage of the natural substrate and subsequent O-O bond formation. While reactions with H2O2 result in slow destruction of the heme, at acidic pH heterolytic cleavage of the O-O bond of PAA cleanly yields the ferryl porphyrin cation radical (compound I). At alkaline pH, the reaction proceeds more rapidly, and the first observed intermediate is a ferryl heme. Freeze-quench EPR confirmed that the latter has an uncoupled protein-based radical, indicating that compound I is the first intermediate formed at all pH values and that radical migration is faster at alkaline pH. These results suggest by analogy that two-electron Cl-O bond cleavage to yield a ferryl-porphyrin cation radical is the most likely initial step in O-O bond formation from chlorite.
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Affiliation(s)
- Jeffrey A Mayfield
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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41
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Mayfield JA, Hammer ND, Kurker RC, Chen TK, Ojha S, Skaar EP, DuBois JL. The chlorite dismutase (HemQ) from Staphylococcus aureus has a redox-sensitive heme and is associated with the small colony variant phenotype. J Biol Chem 2013; 288:23488-504. [PMID: 23737523 PMCID: PMC5395028 DOI: 10.1074/jbc.m112.442335] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 05/23/2013] [Indexed: 01/17/2023] Open
Abstract
The chlorite dismutases (C-family proteins) are a widespread family of heme-binding proteins for which chemical and biological roles remain unclear. An association of the gene with heme biosynthesis in Gram-positive bacteria was previously demonstrated by experiments involving introduction of genes from two Gram-positive species into heme biosynthesis mutant strains of Escherichia coli, leading to the gene being renamed hemQ. To assess the gene product's biological role more directly, a Staphylococcus aureus strain with an inactivated hemQ gene was generated and shown to be a slow growing small colony variant under aerobic but not anaerobic conditions. The small colony variant phenotype is rescued by the addition of exogenous heme despite an otherwise wild type heme biosynthetic pathway. The ΔhemQ mutant accumulates coproporphyrin specifically under aerobic conditions. Although its sequence is highly similar to functional chlorite dismutases, the HemQ protein has no steady state reactivity with chlorite, very modest reactivity with H2O2 or peracetic acid, and no observable transient intermediates. HemQ's equilibrium affinity for heme is in the low micromolar range. Holo-HemQ reconstituted with heme exhibits heme lysis after <50 turnovers with peroxide and <10 turnovers with chlorite. The heme-free apoprotein aggregates or unfolds over time. IsdG-like proteins and antibiotic biosynthesis monooxygenases are close sequence and structural relatives of HemQ that use heme or porphyrin-like organic molecules as substrates. The genetic and biochemical data suggest a similar substrate role for heme or porphyrin, with possible sensor-regulator functions for the protein. HemQ heme could serve as the means by which S. aureus reversibly adopts an SCV phenotype in response to redox stress.
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Affiliation(s)
- Jeffrey A. Mayfield
- From the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Neal D. Hammer
- the Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Richard C. Kurker
- From the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Thomas K. Chen
- the Division of Biological Sciences, SRI International, Harrisonburg, Virginia 22802, and
- the Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59718
| | - Sunil Ojha
- the Division of Biological Sciences, SRI International, Harrisonburg, Virginia 22802, and
| | - Eric P. Skaar
- the Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Jennifer L. DuBois
- the Division of Biological Sciences, SRI International, Harrisonburg, Virginia 22802, and
- the Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59718
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42
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Abstract
UNLABELLED The genes for chlorate reduction in six bacterial strains were analyzed in order to gain insight into the metabolism. A newly isolated chlorate-reducing bacterium (Shewanella algae ACDC) and three previously isolated strains (Ideonella dechloratans, Pseudomonas sp. strain PK, and Dechloromarinus chlorophilus NSS) were genome sequenced and compared to published sequences (Alicycliphilus denitrificans BC plasmid pALIDE01 and Pseudomonas chloritidismutans AW-1). De novo assembly of genomes failed to join regions adjacent to genes involved in chlorate reduction, suggesting the presence of repeat regions. Using a bioinformatics approach and finishing PCRs to connect fragmented contigs, we discovered that chlorate reduction genes are flanked by insertion sequences, forming composite transposons in all four newly sequenced strains. These insertion sequences delineate regions with the potential to move horizontally and define a set of genes that may be important for chlorate reduction. In addition to core metabolic components, we have highlighted several such genes through comparative analysis and visualization. Phylogenetic analysis places chlorate reductase within a functionally diverse clade of type II dimethyl sulfoxide (DMSO) reductases, part of a larger family of enzymes with reactivity toward chlorate. Nucleotide-level forensics of regions surrounding chlorite dismutase (cld), as well as its phylogenetic clustering in a betaproteobacterial Cld clade, indicate that cld has been mobilized at least once from a perchlorate reducer to build chlorate respiration. IMPORTANCE Genome sequencing has identified, for the first time, chlorate reduction composite transposons. These transposons are constructed with flanking insertion sequences that differ in type and orientation between organisms, indicating that this mobile element has formed multiple times and is important for dissemination. Apart from core metabolic enzymes, very little is known about the genetic factors involved in chlorate reduction. Comparative analysis has identified several genes that may also be important, but the relative absence of accessory genes suggests that this mobile metabolism relies on host systems for electron transport, regulation, and cofactor synthesis. Phylogenetic analysis of Cld and ClrA provides support for the hypothesis that chlorate reduction was built multiple times from type II dimethyl sulfoxide (DMSO) reductases and cld. In at least one case, cld has been coopted from a perchlorate reduction island for this purpose. This work is a significant step toward understanding the genetics and evolution of chlorate reduction.
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43
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Blanc B, Rodgers KR, Lukat-Rodgers GS, DuBois JL. Understanding the roles of strictly conserved tryptophan residues in O2 producing chlorite dismutases. Dalton Trans 2012; 42:3156-69. [PMID: 23241559 DOI: 10.1039/c2dt32312e] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The chlorite dismutases (Clds) degrade ClO(2)(-) to O(2) and Cl(-) in perchlorate respiring bacteria, and they serve still poorly defined cellular roles in other diverse microbes. These proteins share 3 highly conserved Trp residues, W155, W156, and W227, on the proximal side of the heme. The Cld from Dechloromonas aromatica (DaCld) has been shown to form protein-based radicals in its reactions with ClO(2)(-) and peracetic acid. The roles of the conserved Trp residues in radical generation and in enzymatic function were assessed via spectroscopic and kinetic analysis of their Phe mutants. The W155F mutant was the most dramatically affected, appearing to lose the characteristic pentameric oligomerization state, secondary structure, and heme binding properties of the WT protein. The W156F mutant initially retains many features of the WT protein but over time acquires many of the features of W155F. Conversion to an inactive, heme-free form is accelerated by dilution, suggesting loss of the protein's pentameric state. Hence, both W155 and W156 are important for heme binding and maintenance of the protein's reactive pentameric structure. W227F by contrast retains many properties of the WT protein. Important differences are noted in the transient kinetic reactions with peracetic acid (PAA), where W227F appears to form an [Fe(IV)=O]-containing intermediate, which subsequently converts to an uncoupled [Fe(IV)=O + AA(+)˙] system in a [PAA]-dependent manner. This is in contrast to the peroxidase-like formation of [Fe(IV)=O] coupled to a porphyrin π-cation radical in the WT protein, which decays in a [PAA]-independent manner. These observations and the lack of redox protection for the heme in any of the Trp mutants suggests a tendency for protein radical formation in DaCld that is independent of any of these conserved active site residues.
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Affiliation(s)
- Beatrice Blanc
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46656, USA
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44
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Hofbauer S, Bellei M, Sündermann A, Pirker KF, Hagmüller A, Mlynek G, Kostan J, Daims H, Furtmüller PG, Djinović-Carugo K, Oostenbrink C, Battistuzzi G, Obinger C. Redox thermodynamics of high-spin and low-spin forms of chlorite dismutases with diverse subunit and oligomeric structures. Biochemistry 2012; 51:9501-12. [PMID: 23126649 PMCID: PMC3557923 DOI: 10.1021/bi3013033] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Chlorite dismutases (Clds) are heme b-containing
oxidoreductases that convert chlorite to chloride and dioxygen. In
this work, the thermodynamics of the one-electron reduction of the
ferric high-spin forms and of the six-coordinate low-spin cyanide
adducts of the enzymes from Nitrobacter winogradskyi (NwCld) and Candidatus “Nitrospira defluvii”
(NdCld) were determined through spectroelectrochemical experiments.
These proteins belong to two phylogenetically separated lineages that
differ in subunit (21.5 and 26 kDa, respectively) and oligomeric (dimeric
and pentameric, respectively) structure but exhibit similar chlorite
degradation activity. The E°′ values
for free and cyanide-bound proteins were determined to be −119
and −397 mV for NwCld and −113 and −404 mV for
NdCld, respectively (pH 7.0, 25 °C). Variable-temperature spectroelectrochemical
experiments revealed that the oxidized state of both proteins is enthalpically
stabilized. Molecular dynamics simulations suggest that changes in
the protein structure are negligible, whereas solvent reorganization
is mainly responsible for the increase in entropy during the redox
reaction. Obtained data are discussed with respect to the known structures
of the two Clds and the proposed reaction mechanism.
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Affiliation(s)
- Stefan Hofbauer
- Department of Chemistry, Division of Biochemistry, VIBT-Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, A-1190 Vienna, Austria
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45
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Ettwig KF, Speth DR, Reimann J, Wu ML, Jetten MSM, Keltjens JT. Bacterial oxygen production in the dark. Front Microbiol 2012; 3:273. [PMID: 22891064 PMCID: PMC3413370 DOI: 10.3389/fmicb.2012.00273] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 07/10/2012] [Indexed: 11/13/2022] Open
Abstract
Nitric oxide (NO) and nitrous oxide (N(2)O) are among nature's most powerful electron acceptors. In recent years it became clear that microorganisms can take advantage of the oxidizing power of these compounds to degrade aliphatic and aromatic hydrocarbons. For two unrelated bacterial species, the "NC10" phylum bacterium "Candidatus Methylomirabilis oxyfera" and the γ-proteobacterial strain HdN1 it has been suggested that under anoxic conditions with nitrate and/or nitrite, monooxygenases are used for methane and hexadecane oxidation, respectively. No degradation was observed with nitrous oxide only. Similarly, "aerobic" pathways for hydrocarbon degradation are employed by (per)chlorate-reducing bacteria, which are known to produce oxygen from chlorite [Formula: see text]. In the anaerobic methanotroph M. oxyfera, which lacks identifiable enzymes for nitrogen formation, substrate activation in the presence of nitrite was directly associated with both oxygen and nitrogen formation. These findings strongly argue for the role of NO, or an oxygen species derived from it, in the activation reaction of methane. Although oxygen generation elegantly explains the utilization of "aerobic" pathways under anoxic conditions, the underlying mechanism is still elusive. In this perspective, we review the current knowledge about intra-aerobic pathways, their potential presence in other organisms, and identify candidate enzymes related to quinol-dependent NO reductases (qNORs) that might be involved in the formation of oxygen.
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Affiliation(s)
- Katharina F Ettwig
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Nijmegen, Netherlands
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46
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Nilsson T, Rova M, Smedja Bäcklund A. Microbial metabolism of oxochlorates: a bioenergetic perspective. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:189-97. [PMID: 22735192 DOI: 10.1016/j.bbabio.2012.06.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 06/05/2012] [Accepted: 06/15/2012] [Indexed: 11/28/2022]
Abstract
The microbial metabolism of oxochlorates is part of the biogeochemical cycle of chlorine. Organisms capable of growth using perchlorate or chlorate as respiratory electron acceptors are also interesting for applications in biotreatment of oxochlorate-containing effluents or bioremediation of contaminated areas. In this review, we discuss the reactions of oxochlorate respiration, the corresponding enzymes, and the relation to respiratory electron transport that can contribute to a proton gradient across the cell membrane. Enzymes specific for oxochlorate respiration are oxochlorate reductases and chlorite dismutase. The former belong to DMSO reductase family of molybdenum-containing enzymes. The heme protein chlorite dismutase, which decomposes chlorite into chloride and molecular oxygen, is only distantly related to other proteins with known functions. Pathways for electron transport may be different in perchlorate and chlorate reducers, but appear in both cases to be similar to pathways found in other respiratory systems. This article is part of a Special Issue entitled: Evolutionary aspects bioenergetic systems.
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Affiliation(s)
- Thomas Nilsson
- Karlstad University, Dept. Chemistry and Biomedical Sciences, SE-651 88 Karlstad, Sweden.
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Hofbauer S, Gysel K, Mlynek G, Kostan J, Hagmüller A, Daims H, Furtmüller PG, Djinović-Carugo K, Obinger C. Impact of subunit and oligomeric structure on the thermal and conformational stability of chlorite dismutases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:1031-8. [PMID: 22683440 PMCID: PMC3787751 DOI: 10.1016/j.bbapap.2012.05.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 05/25/2012] [Accepted: 05/26/2012] [Indexed: 11/16/2022]
Abstract
Chlorite dismutases (Cld) are unique heme b containing oxidoreductases that convert chlorite to chloride and dioxygen. Recent phylogenetic and structural analyses demonstrated that these metalloproteins significantly differ in oligomeric and subunit structure. Here we have analyzed two representatives of two phylogenetically separated lineages, namely pentameric Cld from Candidatus "Nitrospira defluvii" and dimeric Cld from Nitrobacter winogradskyi having a similar enzymatic activity at room temperature. By application of a broad set of techniques including differential scanning calorimetry, electronic circular dichroism, UV-vis and fluorescence spectroscopy the temperature-mediated and chemical unfolding of both recombinant proteins were analyzed. Significant differences in thermal and conformational stability are reported. The pentameric enzyme is very stable between pH 3 and 10 (T(m)=92°C at pH 7.0) and active at high temperatures thus being an interesting candidate for bioremediation of chlorite. By contrast the dimeric protein starts to unfold already at 53°C. The observed unfolding pathways are discussed with respect to the known subunit structure and subunit interaction.
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Affiliation(s)
- Stefan Hofbauer
- University of Natural Resources and Life Sciences, Vienna, Austria
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Blanc B, Mayfield JA, McDonald CA, Lukat-Rodgers GS, Rodgers KR, DuBois JL. Understanding how the distal environment directs reactivity in chlorite dismutase: spectroscopy and reactivity of Arg183 mutants. Biochemistry 2012; 51:1895-910. [PMID: 22313119 DOI: 10.1021/bi2017377] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The chlorite dismutase from Dechloromonas aromatica (DaCld) catalyzes the highly efficient decomposition of chlorite to O(2) and chloride. Spectroscopic, equilibrium thermodynamic, and kinetic measurements have indicated that Cld has two pH sensitive moieties; one is the heme, and Arg183 in the distal heme pocket has been hypothesized to be the second. This active site residue has been examined by site-directed mutagenesis to understand the roles of positive charge and hydrogen bonding in O-O bond formation. Three Cld mutants, Arg183 to Lys (R183K), Arg183 to Gln (R183Q), and Arg183 to Ala (R183A), were investigated to determine their respective contributions to the decomposition of chlorite ion, the spin state and coordination states of their ferric and ferrous forms, their cyanide and imidazole binding affinities, and their reduction potentials. UV-visible and resonance Raman spectroscopies showed that DaCld(R183A) contains five-coordinate high-spin (5cHS) heme, the DaCld(R183Q) heme is a mixture of five-coordinate and six-coordinate high spin (5c/6cHS) heme, and DaCld(R183K) contains six-coordinate low-spin (6cLS) heme. In contrast to wild-type (WT) Cld, which exhibits pK(a) values of 6.5 and 8.7, all three ferric mutants exhibited pH-independent spectroscopic signatures and kinetic behaviors. Steady state kinetic parameters of the chlorite decomposition reaction catalyzed by the mutants suggest that in WT DaCld the pK(a) of 6.5 corresponds to a change in the availability of positive charge from the guanidinium group of Arg183 to the heme site. This could be due to either direct acid-base chemistry at the Arg183 side chain or a flexible Arg183 side chain that can access various orientations. Current evidence is most consistent with a conformational adjustment of Arg183. A properly oriented Arg183 is critical for the stabilization of anions in the distal pocket and for efficient catalysis.
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Affiliation(s)
- Béatrice Blanc
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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Roberts JN, Singh R, Grigg JC, Murphy MEP, Bugg TDH, Eltis LD. Characterization of dye-decolorizing peroxidases from Rhodococcus jostii RHA1. Biochemistry 2011; 50:5108-19. [PMID: 21534572 DOI: 10.1021/bi200427h] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The soil bacterium Rhodococcus jostii RHA1 contains two dye-decolorizing peroxidases (DyPs) named according to the subfamily they represent: DypA, predicted to be periplasmic, and DypB, implicated in lignin degradation. Steady-state kinetic studies of these enzymes revealed that they have much lower peroxidase activities than C- and D-type DyPs. Nevertheless, DypA showed 6-fold greater apparent specificity for the anthraquinone dye Reactive Blue 4 (k(cat)/K(m) = 12800 ± 600 M(-1) s(-1)) than either ABTS or pyrogallol, consistent with previously characterized DyPs. By contrast, DypB showed the greatest apparent specificity for ABTS (k(cat)/K(m) = 2000 ± 100 M(-1) s(-1)) and also oxidized Mn(II) (k(cat)/K(m) = 25.1 ± 0.1 M(-1) s(-1)). Further differences were detected using electron paramagnetic resonance (EPR) spectroscopy: while both DyPs contained high-spin (S = (5)/(2)) Fe(III) in the resting state, DypA had a rhombic high-spin signal (g(y) = 6.32, g(x) = 5.45, and g(z) = 1.97) while DypB had a predominantly axial signal (g(y) = 6.09, g(x) = 5.45, and g(z) = 1.99). Moreover, DypA reacted with H(2)O(2) to generate an intermediate with features of compound II (Fe(IV)═O). By contrast, DypB reacted with H(2)O(2) with a second-order rate constant of (1.79 ± 0.06) × 10(5) M(-1) s(-1) to generate a relatively stable green-colored intermediate (t(1/2) ∼ 9 min). While the electron absorption spectrum of this intermediate was similar to that of compound I of plant-type peroxidases, its EPR spectrum was more consistent with a poorly coupled protein-based radical than with an [Fe(IV)═O Por(•)](+) species. The X-ray crystal structure of DypB, determined to 1.4 Å resolution, revealed a hexacoordinated heme iron with histidine and a solvent species occupying axial positions. A solvent channel potentially provides access to the distal face of the heme for H(2)O(2). A shallow pocket exposes heme propionates to the solvent and contains a cluster of acidic residues that potentially bind Mn(II). Insight into the structure and function of DypB facilitates its engineering for the improved degradation of lignocellulose.
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Affiliation(s)
- Joseph N Roberts
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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Ahmad M, Roberts JN, Hardiman EM, Singh R, Eltis LD, Bugg TDH. Identification of DypB from Rhodococcus jostii RHA1 as a lignin peroxidase. Biochemistry 2011; 50:5096-107. [PMID: 21534568 DOI: 10.1021/bi101892z] [Citation(s) in RCA: 251] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rhodococcus jostii RHA1, a polychlorinated biphenyl-degrading soil bacterium whose genome has been sequenced, shows lignin degrading activity in two recently developed spectrophotometric assays. Bioinformatic analysis reveals two unannotated peroxidase genes present in the genome of R. jostii RHA1 with sequence similarity to open reading frames in other lignin-degrading microbes. They are members of the Dyp peroxidase family and were annotated as DypA and DypB, on the basis of bioinformatic analysis. Assay of gene deletion mutants using a colorimetric lignin degradation assay reveals that a ΔdypB mutant shows greatly reduced lignin degradation activity, consistent with a role in lignin breakdown. Recombinant DypB protein shows activity in the colorimetric assay and shows Michaelis-Menten kinetic behavior using Kraft lignin as a substrate. DypB is activated by Mn(2+) by 5-23-fold using a range of assay substrates, and breakdown of wheat straw lignocellulose by recombinant DypB is observed over 24-48 h in the presence of 1 mM MnCl(2). Incubation of recombinant DypB with a β-aryl ether lignin model compound shows time-dependent turnover, giving vanillin as a product, indicating that C(α)-C(β) bond cleavage has taken place. This reaction is inhibited by addition of diaphorase, consistent with a radical mechanism for C-C bond cleavage. Stopped-flow kinetic analysis of the DypB-catalyzed reaction shows reaction between the intermediate compound I (397 nm) and either Mn(II) (k(obs) = 2.35 s(-1)) or the β-aryl ether (k(obs) = 3.10 s(-1)), in the latter case also showing a transient at 417 nm, consistent with a compound II intermediate. These results indicate that DypB has a significant role in lignin degradation in R. jostii RHA1, is able to oxidize both polymeric lignin and a lignin model compound, and appears to have both Mn(II) and lignin oxidation sites. This is the first detailed characterization of a recombinant bacterial lignin peroxidase.
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Affiliation(s)
- Mark Ahmad
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, UK
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