1
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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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2
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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
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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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3
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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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4
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Conger MA, Cornetta AR, Liptak MD. Spectroscopic Evidence for Electronic Control of Heme Hydroxylation by IsdG. Inorg Chem 2019; 58:15455-15465. [PMID: 31693363 DOI: 10.1021/acs.inorgchem.9b02530] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Staphylococcus aureus IsdG catalyzes a unique trioxygenation of heme to staphylobilin, and the data presented in this article elucidate the mechanism of the novel chemical transformation. More specifically, the roles of the second-sphere Asn and Trp residues in the monooxygenation of ferric-peroxoheme have been clarified via spectroscopic characterization of the ferric-azidoheme analogue. Analysis of UV/vis absorption data quantified the strength of the hydrogen bond that exists between the Asn7 side chain and the azide moiety of ferric-azidoheme. X-band electron paramagnetic resonance data were acquired and analyzed, which revealed that this hydrogen bond weakens the π-donor strength of the azide, resulting in perturbations of the Fe 3d based orbitals. Finally, nuclear magnetic resonance characterization of 13C-enriched samples demonstrated that the Asn7···N3 hydrogen bond triggers partial porphyrin to iron electron transfer, resulting in spin density delocalization onto the heme meso carbons. These spectroscopic experiments were complemented by combined quantum mechanics/molecular mechanics computational modeling, which strongly suggested that the electronic structure changes observed for the N7A variant arose from loss of the Asn7···N3 hydrogen bond as opposed to a decrease in porphyrin ruffling. From these data a fascinating picture emerges where an Asn7···N3 hydrogen bond is communicated through four bonds, resulting in meso carbons with partial cationic radical character that are poised for hydroxylation. This chemistry is not observed in other heme proteins because Asn7 and Trp67 must work in concert to trigger the requisite electronic structure change.
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Affiliation(s)
- Matthew A Conger
- Department of Chemistry , University of Vermont , Burlington , Vermont 05405 , United States
| | - Amanda R Cornetta
- Department of Chemistry , University of Vermont , Burlington , Vermont 05405 , United States
| | - Matthew D Liptak
- Department of Chemistry , University of Vermont , Burlington , Vermont 05405 , United States
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5
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Pfanzagl V, Nys K, Bellei M, Michlits H, Mlynek G, Battistuzzi G, Djinovic-Carugo K, Van Doorslaer S, Furtmüller PG, Hofbauer S, Obinger C. Roles of distal aspartate and arginine of B-class dye-decolorizing peroxidase in heterolytic hydrogen peroxide cleavage. J Biol Chem 2018; 293:14823-14838. [PMID: 30072383 PMCID: PMC6153280 DOI: 10.1074/jbc.ra118.004773] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 07/26/2018] [Indexed: 11/06/2022] Open
Abstract
Dye-decolorizing peroxidases (DyPs) represent the most recently classified hydrogen peroxide-dependent heme peroxidase family. Although widely distributed with more than 5000 annotated genes and hailed for their biotechnological potential, detailed biochemical characterization of their reaction mechanism remains limited. Here, we present the high-resolution crystal structures of WT B-class DyP from the pathogenic bacterium Klebsiella pneumoniae (KpDyP) (1.6 Å) and the variants D143A (1.3 Å), R232A (1.9 Å), and D143A/R232A (1.1 Å). We demonstrate the impact of elimination of the DyP-typical, distal residues Asp-143 and Arg-232 on (i) the spectral and redox properties, (ii) the kinetics of heterolytic cleavage of hydrogen peroxide, (iii) the formation of the low-spin cyanide complex, and (iv) the stability and reactivity of an oxoiron(IV)porphyrin π-cation radical (Compound I). Structural and functional studies reveal that the distal aspartate is responsible for deprotonation of H2O2 and for the poor oxidation capacity of Compound I. Elimination of the distal arginine promotes a collapse of the distal heme cavity, including blocking of one access channel and a conformational change of the catalytic aspartate. We also provide evidence of formation of an oxoiron(IV)-type Compound II in KpDyP with absorbance maxima at 418, 527, and 553 nm. In summary, a reaction mechanism of the peroxidase cycle of B-class DyPs is proposed. Our observations challenge the idea that peroxidase activity toward conventional aromatic substrates is related to the physiological roles of B-class DyPs.
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Affiliation(s)
- Vera Pfanzagl
- From the Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Kevin Nys
- the Department of Physics, University of Antwerp, 2610 Wilrijk, Belgium
| | | | - Hanna Michlits
- From the Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Georg Mlynek
- the Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Gianantonio Battistuzzi
- Chemistry and Geology, University of Modena and Reggio Emilia, via Campi 103, 41125 Modena, Italy, and
| | - Kristina Djinovic-Carugo
- the Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | | | - Paul G Furtmüller
- From the Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Stefan Hofbauer
- From the Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Christian Obinger
- From the Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, 1190 Vienna, Austria,
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6
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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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7
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Schaffner I, Mlynek G, Flego N, Pühringer D, Libiseller-Egger J, Coates L, Hofbauer S, Bellei M, Furtmüller PG, Battistuzzi G, Smulevich G, Djinović-Carugo K, Obinger C. Molecular Mechanism of Enzymatic Chlorite Detoxification: Insights from Structural and Kinetic Studies. ACS Catal 2017; 7:7962-7976. [PMID: 29142780 PMCID: PMC5678291 DOI: 10.1021/acscatal.7b01749] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 09/22/2017] [Indexed: 01/19/2023]
Abstract
![]()
The
heme enzyme chlorite dismutase (Cld) catalyzes the degradation
of chlorite to chloride and dioxygen. Although structure and steady-state
kinetics of Clds have been elucidated, many questions remain (e.g.,
the mechanism of chlorite cleavage and the pH dependence of the reaction).
Here, we present high-resolution X-ray crystal structures of a dimeric
Cld at pH 6.5 and 8.5, its fluoride and isothiocyanate complexes and
the neutron structure at pH 9.0 together with the pH dependence of
the Fe(III)/Fe(II) couple, and the UV–vis and resonance Raman
spectral features. We demonstrate that the distal Arg127 cannot act
as proton acceptor and is fully ionized even at pH 9.0 ruling out
its proposed role in dictating the pH dependence of chlorite degradation.
Stopped-flow studies show that (i) Compound I and hypochlorite do
not recombine and (ii) Compound II is the immediately formed redox
intermediate that dominates during turnover. Homolytic cleavage of
chlorite is proposed.
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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
| | - Georg Mlynek
- Department
for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Dr.-Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Nicola Flego
- Dipartimento
di Chimica “Ugo Schiff”, Università di Firenze, Via della
Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy
| | - Dominic Pühringer
- Department
for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Dr.-Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Julian Libiseller-Egger
- Department
of Chemistry, Division of Biochemistry, BOKU—University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Leighton Coates
- Biology
and Soft Matter Division, Oak Ridge National Laboratory, 1 Bethel
Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Stefan Hofbauer
- 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, Via Campi
103, 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
| | - Gianantonio Battistuzzi
- Department
of Chemistry and Geology, University of Modena and Reggio Emilia, Via Campi 103, 41125 Modena, Italy
| | - Giulietta Smulevich
- Dipartimento
di Chimica “Ugo Schiff”, Università di Firenze, Via della
Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy
| | - Kristina Djinović-Carugo
- Department
for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Dr.-Bohr-Gasse 9, A-1030 Vienna, Austria
- Department
of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - 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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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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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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10
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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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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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