1
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Kardam V, Dubey KD. Tyr 118-Mediated Electron Transfer is Key to the Chlorite Decomposition in Heme-Dependent Chlorite Dismutase. Inorg Chem 2023; 62:18322-18330. [PMID: 37885054 DOI: 10.1021/acs.inorgchem.3c03334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
Chlorite dismutase (Cld) is a crucial enzyme that catalyzes the decomposition of chlorite ions into chloride ions (Cl-) and molecular oxygen (O2). Despite playing an important role in the detoxification of toxic chlorite ions, the mechanism of cleavage of the Cl-O bond by Cld remains highly debatable. The present study highlights the mechanism of such Cl-O bond cleavage in Cld using sophisticated computational tools such as hybrid quantum mechanical/molecular mechanical calculations and long-time scale molecular dynamics simulations. Here, we show that Cld forms a high spin ferric hexacoordinated substrate adduct in the presence of a chlorite ion, which subsequently reduces to a ferrous state. Our study shows a stepwise pathway with the homolytic cleavage of the Cl-O bond that produces a high spin Fe(III)-OH species and a diradicaloid species formed by the combination of a chlorine-based ClO• radical and a protein-based tyrosine118• radical. The findings provide significant insights into Cl-O bond cleavage and O2 formation which shows a crucial role of the tyrosine118 during the electron transfer process.
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Affiliation(s)
- Vandana Kardam
- Department of Chemistry, School of Natural Science, Shiv Nadar Institution of Eminence Delhi NCR, NH91 Tehsil Dadri, Greater Noida, Uttar Pradesh 201314, India
| | - Kshatresh Dutta Dubey
- Department of Chemistry, School of Natural Science, Shiv Nadar Institution of Eminence Delhi NCR, NH91 Tehsil Dadri, Greater Noida, Uttar Pradesh 201314, India
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2
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Geeraerts Z, Stiller OR, Lukat-Rodgers GS, Rodgers KR. Roles of High-Valent Hemes and pH Dependence in Halite Decomposition Catalyzed by Chlorite Dismutase from Dechloromonas aromatica. ACS Catal 2022; 12:8641-8657. [DOI: 10.1021/acscatal.2c01428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Zachary Geeraerts
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Olivia R. Stiller
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Gudrun S. Lukat-Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Kenton R. Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
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3
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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
![]()
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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4
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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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5
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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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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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7
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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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8
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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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9
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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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10
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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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11
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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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12
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Linde D, Ruiz-Dueñas FJ, Fernández-Fueyo E, Guallar V, Hammel KE, Pogni R, Martínez AT. Basidiomycete DyPs: Genomic diversity, structural-functional aspects, reaction mechanism and environmental significance. Arch Biochem Biophys 2015; 574:66-74. [PMID: 25637654 DOI: 10.1016/j.abb.2015.01.018] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 01/15/2015] [Accepted: 01/21/2015] [Indexed: 11/26/2022]
Abstract
The first enzyme with dye-decolorizing peroxidase (DyP) activity was described in 1999 from an arthroconidial culture of the fungus Bjerkandera adusta. However, the first DyP sequence had been deposited three years before, as a peroxidase gene from a culture of an unidentified fungus of the family Polyporaceae (probably Irpex lacteus). Since the first description, fewer than ten basidiomycete DyPs have been purified and characterized, but a large number of sequences are available from genomes. DyPs share a general fold and heme location with chlorite dismutases and other DyP-type related proteins (such as Escherichia coli EfeB), forming the CDE superfamily. Taking into account the lack of an evolutionary relationship with the catalase-peroxidase superfamily, the observed heme pocket similarities must be considered as a convergent type of evolution to provide similar reactivity to the enzyme cofactor. Studies on the Auricularia auricula-judae DyP showed that high-turnover oxidation of anthraquinone type and other DyP substrates occurs via long-range electron transfer from an exposed tryptophan (Trp377, conserved in most basidiomycete DyPs), whose catalytic radical was identified in the H2O2-activated enzyme. The existence of accessory oxidation sites in DyP is suggested by the residual activity observed after site-directed mutagenesis of the above tryptophan. DyP degradation of substituted anthraquinone dyes (such as Reactive Blue 5) most probably proceeds via typical one-electron peroxidase oxidations and product breakdown without a DyP-catalyzed hydrolase reaction. Although various DyPs are able to break down phenolic lignin model dimers, and basidiomycete DyPs also present marginal activity on nonphenolic dimers, a significant contribution to lignin degradation is unlikely because of the low activity on high redox-potential substrates.
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Affiliation(s)
- Dolores Linde
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Spain
| | | | - Elena Fernández-Fueyo
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Spain
| | - Victor Guallar
- Joint BSC-CRG-IRB Research Program in Computational Biology, Barcelona Supercomputing Center, Jordi Girona 29, E-08034 Barcelona, Spain; ICREA, Passeig Lluís Companys 23, E-08010 Barcelona, Spain
| | - Kenneth E Hammel
- US Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 53726, USA
| | - Rebecca Pogni
- Dept. Biotechnologies, Chemistry and Pharmacy, University of Siena, I-53100 Siena, Italy
| | - Angel T Martínez
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Spain.
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13
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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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14
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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
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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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15
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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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16
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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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17
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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: 26] [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
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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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18
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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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