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Kato H, Takahashi Y, Suzuki H, Ohashi K, Kawashima R, Nakamura K, Sakai K, Hori C, Takasuka TE, Kato M, Shimizu M. Identification and characterization of methoxy- and dimethoxyhydroquinone 1,2-dioxygenase from Phanerochaete chrysosporium. Appl Environ Microbiol 2024; 90:e0175323. [PMID: 38259078 PMCID: PMC10880611 DOI: 10.1128/aem.01753-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 12/15/2023] [Indexed: 01/24/2024] Open
Abstract
White-rot fungi, such as Phanerochaete chrysosporium, are the most efficient degraders of lignin, a major component of plant biomass. Enzymes produced by these fungi, such as lignin peroxidases and manganese peroxidases, break down lignin polymers into various aromatic compounds based on guaiacyl, syringyl, and hydroxyphenyl units. These intermediates are further degraded, and the aromatic ring is cleaved by 1,2,4-trihydroxybenzene dioxygenases. This study aimed to characterize homogentisate dioxygenase (HGD)-like proteins from P. chrysosporium that are strongly induced by the G-unit fragment of vanillin. We overexpressed two homologous recombinant HGDs, PcHGD1 and PcHGD2, in Escherichia coli. Both PcHGD1 and PcHGD2 catalyzed the ring cleavage in methoxyhydroquinone (MHQ) and dimethoxyhydroquinone (DMHQ). The two enzymes had the highest catalytic efficiency (kcat/Km) for MHQ, and therefore, we named PcHGD1 and PcHGD2 as MHQ dioxygenases 1 and 2 (PcMHQD1 and PcMHQD2), respectively, from P. chrysosporium. This is the first study to identify and characterize MHQ and DMHQ dioxygenase activities in members of the HGD superfamily. These findings highlight the unique and broad substrate spectra of PcHGDs, rendering them attractive candidates for biotechnological applications.IMPORTANCEThis study aimed to elucidate the properties of enzymes responsible for degrading lignin, a dominant natural polymer in terrestrial lignocellulosic biomass. We focused on two homogentisate dioxygenase (HGD) homologs from the white-rot fungus, P. chrysosporium, and investigated their roles in the degradation of lignin-derived aromatic compounds. In the P. chrysosporium genome database, PcMHQD1 and PcMHQD2 were annotated as HGDs that could cleave the aromatic rings of methoxyhydroquinone (MHQ) and dimethoxyhydroquinone (DMHQ) with a preference for MHQ. These findings suggest that MHQD1 and/or MHQD2 play important roles in the degradation of lignin-derived aromatic compounds by P. chrysosporium. The preference of PcMHQDs for MHQ and DMHQ not only highlights their potential for biotechnological applications but also underscores their critical role in understanding lignin degradation by a representative of white-rot fungus, P. chrysosporium.
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Affiliation(s)
- Hiroyuki Kato
- Faculty of Agriculture, Meijo University, Nagoya, Japan
| | | | | | - Keisuke Ohashi
- Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | | | - Koki Nakamura
- Faculty of Agriculture, Meijo University, Nagoya, Japan
| | - Kiyota Sakai
- Faculty of Agriculture, Meijo University, Nagoya, Japan
| | - Chiaki Hori
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan
| | | | - Masashi Kato
- Faculty of Agriculture, Meijo University, Nagoya, Japan
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A robust bacterial high-throughput screening system to evaluate single nucleotide polymorphisms of human homogentisate 1,2-dioxygenase in the context of alkaptonuria. Sci Rep 2022; 12:19452. [PMID: 36376482 PMCID: PMC9663557 DOI: 10.1038/s41598-022-23702-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 11/03/2022] [Indexed: 11/16/2022] Open
Abstract
Alkaptonuria (AKU) is a rare inborn error of metabolism caused by a defective homogentisate 1,2-dioxygenase (HGD), an enzyme involved in the tyrosine degradation pathway. Loss of HGD function leads to the accumulation of homogentisic acid (HGA) in connective body tissues in a process called ochronosis, which results on the long term in an early-onset and severe osteoarthropathy. HGD's quaternary structure is known to be easily disrupted by missense mutations, which makes them an interesting target for novel treatment strategies that aim to rescue enzyme activity. However, only prediction models are available providing information on a structural basis. Therefore, an E. coli based whole-cell screening was developed to evaluate HGD missense variants in 96-well microtiter plates. The screening principle is based on HGD's ability to convert the oxidation sensitive HGA into maleylacetoacetate. More precisely, catalytic activity could be deduced from pyomelanin absorbance measurements, derived from the auto-oxidation of remaining HGA. Optimized screening conditions comprised several E. coli expression strains, varied expression temperatures and varied substrate concentrations. In addition, plate uniformity, signal variability and spatial uniformity were investigated and optimized. Finally, eight HGD missense variants were generated via site-directed mutagenesis and evaluated with the developed high-throughput screening (HTS) assay. For the HTS assay, quality parameters passed the minimum acceptance criterion for Z' values > 0.4 and single window values > 2. We found that activity percentages versus wildtype HGD were 70.37 ± 3.08% (for M368V), 68.78 ± 6.40% (for E42A), 58.15 ± 1.16% (for A122V), 69.07 ± 2.26% (for Y62C), 35.26 ± 1.90% (for G161R), 35.86 ± 1.14% (for P230S), 23.43 ± 4.63% (for G115R) and 19.57 ± 11.00% (for G361R). To conclude, a robust, simple, and cost-effective HTS system was developed to reliably evaluate and distinguish human HGD missense variants by their HGA consumption ability. This HGA quantification assay may lay the foundation for the development of novel treatment strategies for missense variants in AKU.
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Lorquin F, Piccerelle P, Orneto C, Robin M, Lorquin J. New insights and advances on pyomelanin production: from microbial synthesis to applications. J Ind Microbiol Biotechnol 2022; 49:6575554. [PMID: 35482661 PMCID: PMC9338888 DOI: 10.1093/jimb/kuac013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 04/21/2022] [Indexed: 11/14/2022]
Abstract
Pyomelanin is a brown-black phenolic polymer and results from the oxidation of homogentisic acid (HGA) in the L-tyrosine pathway. As part of the research for natural and active ingredients issued from realistic bioprocesses, this work re-evaluates the HGA pigment and makes an updated inventory of its syntheses, microbial pathways, and properties, with tracks and recent advances for its large-scale production. The mechanism of the HGA polymerization is also well documented. In alkaptonuria, pyomelanin formation leads to connective tissue damages and arthritis, most probably due to the ROS issued from HGA oxidation. While UV radiation on human melanin may generate degradation products, pyomelanin is not photodegradable, is hyperthermostable, and has other properties better than the L-Dopa melanin. This review aims to raise awareness about the potential of this pigment for various applications, not only for skin coloring and protection but also for other cells, materials, and as a promising (semi)conductor for bioelectronics and energy.
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Affiliation(s)
- Faustine Lorquin
- Aix-Marseille Université, Mediterranean Institute of Oceanology (MIO), 163 avenue de Luminy, 13288 Marseille Cedex 9, France.,Aix-Marseille Université, Mediterranean Institute of Marine and Terrestrial Biodiversity and Ecology (IMBE), 27 boulevard Jean Moulin, 13385 Marseille Cedex 5, France
| | - Philippe Piccerelle
- Aix-Marseille Université, Mediterranean Institute of Marine and Terrestrial Biodiversity and Ecology (IMBE), 27 boulevard Jean Moulin, 13385 Marseille Cedex 5, France
| | - Caroline Orneto
- Aix-Marseille Université, Mediterranean Institute of Marine and Terrestrial Biodiversity and Ecology (IMBE), 27 boulevard Jean Moulin, 13385 Marseille Cedex 5, France
| | - Maxime Robin
- Aix-Marseille Université, Mediterranean Institute of Marine and Terrestrial Biodiversity and Ecology (IMBE), 27 boulevard Jean Moulin, 13385 Marseille Cedex 5, France
| | - Jean Lorquin
- Aix-Marseille Université, Mediterranean Institute of Oceanology (MIO), 163 avenue de Luminy, 13288 Marseille Cedex 9, France
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Banerjee A, Li J, Molenda MA, Brennessel WW, Chavez FA. A Biomimetic System for Studying Salicylate Dioxygenase. ACS SYMPOSIUM SERIES. AMERICAN CHEMICAL SOCIETY 2019; 1317:71-83. [PMID: 33967356 PMCID: PMC8101989 DOI: 10.1021/bk-2019-1317.ch004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We report the characterization of [Fe(T1Et4iPrIP)(sal)] (2) (T1Et4iPrIP = tris(1-ethyl-4-isopropyl-imidazolyl)phosphine; sal2- = salicylate dianion), which serves as a model for substrate-bound salicylate dioxygenase (SDO). Complex 2 crystallizes in the monoclinic space group P21/n with a = 10.7853(12) Å, b = 16.5060(19) Å, c = 21.217(2) Å, β = 94.489(2)°, and V = 3765.5(7) Å3. The structure consists of FeII bonded in distorted square pyramidal geometry (τ = 0.32) with two salicylate oxygens and two T1Et4iPrIP nitrogens serving as the base and the apical position occupied by the other ligand nitrogen. [Fe(T1Et4iPrIP)(OTf)2] (1), the precursor for 2, catalyzes the cleavage of 1,4-dihydroxy-2-naphthoate in the presence of O2. Complex 1 is also capable of cleaving the salicylate aromatic ring in the presence of H2O2. The progression of this reaction toward product formation involves an FeIII-phenoxide species.
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Affiliation(s)
- Atanu Banerjee
- Department of Chemistry, Oakland University, Rochester, MI 48309-4477, United States
| | - Jia Li
- Department of Chemistry, Oakland University, Rochester, MI 48309-4477, United States
| | - Monika A. Molenda
- Department of Chemistry, Oakland University, Rochester, MI 48309-4477, United States
| | - William W. Brennessel
- Department of Chemistry, University of Rochester, Rochester, NY 14627-0216, United States
| | - Ferman A. Chavez
- Department of Chemistry, University of Rochester, Rochester, NY 14627-0216, United States
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Jiang J, Yu Y, Wang L, Li J, Ling J, Li Y, Duan G. Enzyme immobilized on polyamidoamine-coated magnetic microspheres for α-glucosidase inhibitors screening from Radix Paeoniae Rubra extracts accompanied with molecular modeling. Talanta 2018; 195:127-136. [PMID: 30625522 DOI: 10.1016/j.talanta.2018.11.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 10/29/2018] [Accepted: 11/04/2018] [Indexed: 11/25/2022]
Abstract
In this study, a method for direct screening and identification of α-glucosidase inhibitors (AGIs) from extracts of natural products was established based on polyamidoamine (PAMAM) coated magnetic microspheres. A facile route to synthesize the magnetic PAMAM was employed and α-glucosidase was successfully covalently attached to its surface through cross linking of glutaraldehyde. Using the enzyme-loaded magnetic microspheres, potential inhibitors were fished out from crude extracts directly, followed by structure confirmation. The inhibitory activities of the screened components were further investigated by the enzyme-loaded magnetic microspheres. The Fe3O4 @PAMAM@α-Glu microspheres displayed favorable dispersibility, fast magnetic separation, large enzyme binding amount (42.9 μg•mg-1) and high enzyme activity. Moreover, the α-glucosidase on the surface of PAMAM coating maintained high storage stability and remarkable reusability. Taking advantage of specific interaction of the α-glucosidase with AGIs, the materials could selectively capture a known AGI (+)-catechin under the interference of an inactive compound salicylic acid, with a binding capacity as high as 15.4%. Additionally, using the Fe3O4 @PAMAM@α-Glu microspheres in the inhibition assay, the enzymatic reaction could be stopped by magnetic separation instead of the traditional addition of Na2CO3 solution, which not only eliminated the disturbance of termination reagent to the results, but also reused the immobilized α-glucosidase. The screening and inhibitory activity verification of potential ligands in Radix Paeoniae Rubra ("Chi-shao" in Chinese) extracts were achieved by using Fe3O4 @PAMAM@α-Glu microspheres, demonstrating practical applicability of our method. Therefore, the magnetic PAMAM-based screening approach could be a feasible and alternative strategy for discovering enzyme inhibitors from natural product extracts.
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Affiliation(s)
- Jiebing Jiang
- Fudan University Affiliated Pudong Medical Center & Pharmaceutical Analysis Department, School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Yingjia Yu
- Fudan University Affiliated Pudong Medical Center & Pharmaceutical Analysis Department, School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Liping Wang
- Jing'an District Central Hospital, Fudan University, 259 Xikang Road, Shanghai 200040, China
| | - Jiajia Li
- Fudan University Affiliated Pudong Medical Center & Pharmaceutical Analysis Department, School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Jin Ling
- Department of Biochemical Drugs and Biological Products, Shanghai Institute for Food and Drug Control, No.1500 Zhangheng Road, Pudong New District, Shanghai 201203, China
| | - Yan Li
- Fudan University Affiliated Pudong Medical Center & Pharmaceutical Analysis Department, School of Pharmacy, Fudan University, Shanghai 201203, China.
| | - Gengli Duan
- Fudan University Affiliated Pudong Medical Center & Pharmaceutical Analysis Department, School of Pharmacy, Fudan University, Shanghai 201203, China.
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Colabroy KL, Mayer K. Benchtop Immobilized Metal Affinity Chromatography, Reconstitution and Assay of a Polyhistidine Tagged Metalloenzyme for the Undergraduate Laboratory. J Vis Exp 2018. [PMID: 30199034 PMCID: PMC6231711 DOI: 10.3791/58012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Benchtop immobilized metal affinity chromatography (IMAC), of polyhistidine tagged proteins is easily mastered by undergraduate students and has become the most widely used protein purification method in the modern literature. But, the application of affinity chromatography to metal binding proteins, especially those with redox sensitive metals such as iron, is often limited to laboratories with access to a glove box - equipment that is not routinely available in the undergraduate laboratory. In this article, we demonstrate our benchtop methods for isolation, IMAC purification and metal-ion reconstitution of a poly-histidine tagged, redox-active, non-heme iron binding extradiol dioxygenase and the assay of the dioxygenase with varied substrate concentrations and saturating oxygen. These methods are executed by undergraduate students and implemented in the undergraduate teaching and research laboratory with instrumentation that is accessible and affordable at primarily undergraduate institutions.
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8
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Qi Y, Lu J, Lai W. Insights into the Reaction Mechanism of Aromatic Ring Cleavage by Homogentisate Dioxygenase: A Quantum Mechanical/Molecular Mechanical Study. J Phys Chem B 2016; 120:4579-90. [PMID: 27119315 DOI: 10.1021/acs.jpcb.6b03006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To elucidate the reaction mechanism of the ring cleavage of homogentisate by homogentisate dioxygenase, quantum mechanical/molecular mechanical (QM/MM) calculations were carried out by using two systems in different protonation states of the substrate C2 hydroxyl group. When the substrate C2 hydroxyl group is ionized (the ionized pathway), the superoxo attack on the substrate is the rate-limiting step in the catalytic cycle, with a barrier of 15.9 kcal/mol. Glu396 was found to play an important role in stabilizing the bridge species and its O-O cleavage product by donating a proton via a hydrogen-bonded water molecule. When the substrate C2 hydroxyl group is not ionized (the nonionized pathway), the O-O bond cleavage of the bridge species is the rate-limiting step, with a barrier of 15.3 kcal/mol. The QM/MM-optimized geometries for the dioxygen and alkylperoxo complexes using the nonionized model (for the C2 hydroxyl group) are in agreement with the experimental crystal structures, suggesting that the C2 hydroxyl group is more likely to be nonionized.
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Affiliation(s)
- Yue Qi
- Department of Chemistry, Renmin University of China , Beijing, 100872, China
| | - Jiarui Lu
- Department of Chemistry, Renmin University of China , Beijing, 100872, China
| | - Wenzhen Lai
- Department of Chemistry, Renmin University of China , Beijing, 100872, China
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9
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Evaluation of toxicological biomarkers in secreted proteins of HepG2 cells exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin and their expressions in the plasma of rats and incineration workers. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:584-93. [DOI: 10.1016/j.bbapap.2016.02.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 02/16/2016] [Accepted: 02/22/2016] [Indexed: 11/21/2022]
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10
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Hernández-Ortega A, Quesne MG, Bui S, Heyes DJ, Steiner RA, Scrutton NS, de Visser SP. Catalytic Mechanism of Cofactor-Free Dioxygenases and How They Circumvent Spin-Forbidden Oxygenation of Their Substrates. J Am Chem Soc 2015; 137:7474-87. [DOI: 10.1021/jacs.5b03836] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Aitor Hernández-Ortega
- Manchester
Institute of Biotechnology and Faculty of Life Sciences, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Matthew G. Quesne
- Manchester
Institute of Biotechnology and School of Chemical Engineering and
Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Soi Bui
- Randall
Division of Cell and Molecular Biophysics, King’s College London, London SE1 1UL, United Kingdom
| | - Derren J. Heyes
- Manchester
Institute of Biotechnology and Faculty of Life Sciences, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Roberto A. Steiner
- Randall
Division of Cell and Molecular Biophysics, King’s College London, London SE1 1UL, United Kingdom
| | - Nigel S. Scrutton
- Manchester
Institute of Biotechnology and Faculty of Life Sciences, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Sam P. de Visser
- Manchester
Institute of Biotechnology and School of Chemical Engineering and
Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
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Barry KP, Ngu A, Cohn EF, Cote JM, Burroughs AM, Gerbino JP, Taylor EA. Exploring allosteric activation of LigAB from Sphingobium sp. strain SYK-6 through kinetics, mutagenesis and computational studies. Arch Biochem Biophys 2015; 567:35-45. [PMID: 25562402 DOI: 10.1016/j.abb.2014.12.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 12/19/2014] [Accepted: 12/22/2014] [Indexed: 12/12/2022]
Abstract
The protocatechuate 4,5-dioxygenase (LigAB) from Sphingobium sp. strain SYK-6 is the defining member of the Type II extradiol dioxygenase superfamily (a.k.a. PCA Dioxygenase Superfamily or PCADSF) and plays a key aromatic ring-opening role in the metabolism of several lignin derived aromatic compounds. In our search for alternate substrates and inhibitors of LigAB, we discovered allosteric rate enhancement in the presence of non-substrate protocatechuate-like aldehydes such as vanillin. LigAB has the broadest substrate utilization profile of all protocatechuate (PCA) 4,5-dioxygenase described in the literature, however, the rate enhancement is only observed with PCA, with vanillin increasing kcat for LigAB by 36%. Computational docking has identified a potential site of allosteric binding near the entrance to the active site. Examination of a multiple sequence alignment reveals that many of the residues contributing to this newly identified allosteric pocket are highly conserved within the LigB family of the PCADSF. Point mutants of Phe103α and Ala18β, two residues located in the putative allosteric pocket, display altered rate enhancement as compared to LigAB-WT, providing support for the computationally identified allosteric binding site. Further investigation of this binding site may provide insight into the mechanism of this never before observed allosteric activation in extradiol dioxygenases.
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Affiliation(s)
| | - Abraham Ngu
- Department of Chemistry, Wesleyan University, Middletown, CT 06459, USA
| | - Erin Frances Cohn
- Department of Chemistry, Wesleyan University, Middletown, CT 06459, USA
| | - Joy Marie Cote
- Department of Chemistry, Wesleyan University, Middletown, CT 06459, USA
| | - A Maxwell Burroughs
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | | | - Erika Anne Taylor
- Department of Chemistry, Wesleyan University, Middletown, CT 06459, USA.
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Barry KP, Taylor EA. Characterizing the promiscuity of LigAB, a lignin catabolite degrading extradiol dioxygenase from Sphingomonas paucimobilis SYK-6. Biochemistry 2013; 52:6724-36. [PMID: 23977959 DOI: 10.1021/bi400665t] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
LigAB from Sphingomonas paucimobilis SYK-6 is the only structurally characterized dioxygenase of the largely uncharacterized superfamily of Type II extradiol dioxygenases (EDO). This enzyme catalyzes the oxidative ring-opening of protocatechuate (3,4-dihydroxybenzoic acid or PCA) in a pathway allowing the degradation of lignin derived aromatic compounds (LDACs). LigAB has also been shown to utilize two other LDACs from the same metabolic pathway as substrates, gallate, and 3-O-methyl gallate; however, kcat/KM had not been reported for any of these compounds. In order to assess the catalytic efficiency and get insights into the observed promiscuity of this enzyme, steady-state kinetic analyses were performed for LigAB with these and a library of related compounds. The dioxygenation of PCA by LigAB was highly efficient, with a kcat of 51 s(-1) and a kcat/KM of 4.26 × 10(6) M(-1)s(-1). LigAB demonstrated the ability to use a variety of catecholic molecules as substrates beyond the previously identified gallate and 3-O-methyl gallate, including 3,4-dihydroxybenzamide, homoprotocatechuate, catechol, and 3,4-dihydroxybenzonitrile. Interestingly, 3,4-dihydroxybenzamide (DHBAm) behaves in a manner similar to that of the preferred benzoic acid substrates, with a kcat/Km value only ∼4-fold lower than that for gallate and ∼10-fold higher than that for 3-O-methyl gallate. All of these most active substrates demonstrate mechanistic inactivation of LigAB. Additionally, DHBAm exhibits potent product inhibition that leads to an inactive enzyme, being more highly deactivating at lower substrate concentration, a phenomena that, to our knowledge, has not been reported for another dioxygenase substrate/product pair. These results provide valuable catalytic insight into the reactions catalyzed by LigAB and make it the first Type II EDO that is fully characterized both structurally and kinetically.
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Affiliation(s)
- Kevin P Barry
- Department of Chemistry, Wesleyan University , 52 Lawn Avenue, Middletown, Connecticut 06459, United States
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Visualizing the substrate-, superoxo-, alkylperoxo-, and product-bound states at the nonheme Fe(II) site of homogentisate dioxygenase. Proc Natl Acad Sci U S A 2013; 110:12625-30. [PMID: 23858455 DOI: 10.1073/pnas.1302144110] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Homogentisate 1,2-dioxygenase (HGDO) uses a mononuclear nonheme Fe(2+) to catalyze the oxidative ring cleavage in the degradation of Tyr and Phe by producing maleylacetoacetate from homogentisate (2,5-dihydroxyphenylacetate). Here, we report three crystal structures of HGDO, revealing five different steps in its reaction cycle at 1.7-1.98 Å resolution. The resting state structure displays an octahedral coordination for Fe(2+) with two histidine residues (His331 and His367), a bidentate carboxylate ligand (Glu337), and two water molecules. Homogentisate binds as a monodentate ligand to Fe(2+), and its interaction with Tyr346 invokes the folding of a loop over the active site, effectively shielding it from solvent. Binding of homogentisate is driven by enthalpy and is entropically disfavored as shown by anoxic isothermal titration calorimetry. Three different reaction cycle intermediates have been trapped in different HGDO subunits of a single crystal showing the influence of crystal packing interactions on the course of enzymatic reactions. The observed superoxo:semiquinone-, alkylperoxo-, and product-bound intermediates have been resolved in a crystal grown anoxically with homogentisate, which was subsequently incubated with dioxygen. We demonstrate that, despite different folds, active site architectures, and Fe(2+) coordination, extradiol dioxygenases can proceed through the same principal reaction intermediates to catalyze the O2-dependent cleavage of aromatic rings. Thus, convergent evolution of nonhomologous enzymes using the 2-His-1-carboxylate facial triad motif developed different solutions to stabilize closely related intermediates in unlike environments.
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Bittner MM, Kraus D, Lindeman SV, Popescu CV, Fiedler AT. Synthetic, spectroscopic, and DFT studies of iron complexes with iminobenzo(semi)quinone ligands: implications for o-aminophenol dioxygenases. Chemistry 2013; 19:9686-98. [PMID: 23744733 PMCID: PMC3965334 DOI: 10.1002/chem.201300520] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 04/17/2013] [Indexed: 11/10/2022]
Abstract
The oxidative C-C bond cleavage of o-aminophenols by nonheme Fe dioxygenases is a critical step in both human metabolism (the kynurenine pathway) and the microbial degradation of nitroaromatic pollutants. The catalytic cycle of o-aminophenol dioxygenases (APDOs) has been proposed to involve formation of an Fe(II)/O2/iminobenzosemiquinone complex, although the presence of a substrate radical has been called into question by studies of related ring-cleaving dioxygenases. Recently, we reported the first synthesis of an iron(II) complex coordinated to an iminobenzosemiquinone (ISQ) ligand, namely, [Fe((Ph2)Tp)((tBu)ISQ)] (2a; where (Ph2)Tp=hydrotris(3,5-diphenylpyrazol-1-yl)borate and (tBu)ISQ is the radical anion derived from 2-amino-4,6-di-tert-butylphenol). In the current manuscript, density functional theory (DFT) calculations and a wide variety of spectroscopic methods (electronic absorption, Mössbauer, magnetic circular dichroism, and resonance Raman) were employed to obtain detailed electronic-structure descriptions of 2a and its one-electron oxidized derivative [3a](+). In addition, we describe the synthesis and characterization of a parallel series of complexes featuring the neutral supporting ligand tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine ((Ph2)TIP). The isomer shifts of about 0.97 mm s(-1) obtained through Mössbauer experiments confirm that 2a (and its (Ph2)TIP-based analogue [2b](+)) contain Fe(II) centers, and the presence of an ISQ radical was verified by analysis of the absorption spectra in light of time-dependent DFT calculations. The collective spectroscopic data indicate that one-electron oxidation of the Fe(II)-ISQ complexes yields complexes ([3a](+) and [3b](2+)) with electronic configurations between the Fe(III)-ISQ and Fe(II)-IBQ limits (IBQ=iminobenzoquinone), highlighting the ability of o-amidophenolates to access multiple oxidation states. The implications of these results for the mechanism of APDOs and other ring-cleaving dioxygenases are discussed.
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Affiliation(s)
- Michael M. Bittner
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States
| | - David Kraus
- Department of Chemistry, Ursinus College, Collegeville, Pennsylvania 19426, United States
| | - Sergey V. Lindeman
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States
| | - Codrina V. Popescu
- Department of Chemistry, Ursinus College, Collegeville, Pennsylvania 19426, United States
| | - Adam T. Fiedler
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States
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Baum AE, Park H, Wang D, Lindeman SV, Fiedler AT. Structural, spectroscopic, and electrochemical properties of nonheme Fe(II)-hydroquinonate complexes: synthetic models of hydroquinone dioxygenases. Dalton Trans 2012; 41:12244-53. [PMID: 22930005 PMCID: PMC3891569 DOI: 10.1039/c2dt31504a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using the tris(3,5-diphenylpyrazol-1-yl)borate ((Ph2)Tp) supporting ligand, a series of mono- and dinuclear ferrous complexes containing hydroquinonate (HQate) ligands have been prepared and structurally characterized with X-ray crystallography. The monoiron(II) complexes serve as faithful mimics of the substrate-bound form of hydroquinone dioxygenases (HQDOs) - a family of nonheme Fe enzymes that catalyze the oxidative cleavage of 1,4-dihydroxybenzene units. Reflecting the variety of HQDO substrates, the synthetic complexes feature both mono- and bidentate HQate ligands. The bidentate HQates cleanly provide five-coordinate, high-spin Fe(II) complexes with the general formula [Fe((Ph2)Tp)(HL(X))] (1X), where HL(X) is a HQate(1-) ligand substituted at the 2-position with a benzimidazolyl (1A), acetyl (1B and 1C), or methoxy (1D) group. In contrast, the monodentate ligand 2,6-dimethylhydroquinone (H(2)L(F)) exhibited a greater tendency to bridge between two Fe(II) centers, resulting in formation of [Fe(2)((Ph2)Tp)(2)(μ-L(F))(MeCN)]·[2F(MeCN)]. However, addition of one equivalent of "free" pyrazole ((Ph2)pz) ligand provided the mononuclear complex, [Fe((Ph2)Tp)(HL(F))((Ph2)pz)]·[1F((Ph2)pz)], which is stabilized by an intramolecular hydrogen bond between the HL(F) and (Ph2)pz donors. Complex 1F((Ph2)pz) represents the first crystallographically-characterized example of a monoiron complex bound to an untethered HQate ligand. The geometric and electronic structures of the Fe/HQate complexes were further probed with spectroscopic (UV-vis absorption, (1)H NMR) and electrochemical methods. Cyclic voltammograms of complexes in the 1X series revealed an Fe-based oxidation between 0 and -300 mV (vs. Fc(+/0)), in addition to irreversible oxidation(s) of the HQate ligand at higher potentials. The one-electron oxidized species (1X(OX)) were examined with UV-vis absorption and electron paramagnetic resonance (EPR) spectroscopies.
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Affiliation(s)
- Amanda E. Baum
- Department of Chemistry, Marquette University, Milwaukee, WI 53201-1881
| | - Heaweon Park
- Department of Chemistry, Marquette University, Milwaukee, WI 53201-1881
| | - Denan Wang
- Department of Chemistry, Marquette University, Milwaukee, WI 53201-1881
| | | | - Adam T. Fiedler
- Department of Chemistry, Marquette University, Milwaukee, WI 53201-1881
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Machonkin TE, Doerner AE. Substrate Specificity of Sphingobium chlorophenolicum 2,6-Dichlorohydroquinone 1,2-Dioxygenase. Biochemistry 2011; 50:8899-913. [DOI: 10.1021/bi200855m] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Timothy E. Machonkin
- Department of Chemistry, Whitman College, 345 Boyer Avenue, Walla Walla, Washington
99362, United States
| | - Amy E. Doerner
- Department of Chemistry, Whitman College, 345 Boyer Avenue, Walla Walla, Washington
99362, United States
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17
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Molecular cloning of the HGD gene and association of SNPs with meat quality traits in Chinese red cattle. Mol Biol Rep 2010; 37:603-11. [PMID: 19816789 DOI: 10.1007/s11033-009-9860-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 09/28/2009] [Indexed: 10/20/2022]
Abstract
Homogentisate 1, 2 dioxygenase (HGD) is one of six enzymes required for the catabolism of the aromatic amino acids phenylalanine and tyrosine. Here we present the nucleotide sequence of transcripts of the bovine HGD gene. The full length cDNA of bovine HGD has been identified, encoding a deduced protein of 445 amino acids (Accession No. FJ515744). The bovine HGD gene comprises 14 exons and 13 introns. This is the first published cDNA bovine sequences that share high sequence similarity with other species. Semi-quantitative RT-PCR analysis demonstrated that the bovine HGD transcript was mainly expressed in liver and kidney tissues. Nine single nucleotide polymorphisms (SNPs) were identified, five in the coding region and four intronic. Four of the SNPs change an amino acid in the HGD protein sequence. Genotype and allelic frequencies were determined in Chinese red cattle breeds. Ten haplotypes were determined based upon the genotype of 9 SNPs. Moreover, for the first time an association was reported between HGD gene polymorphism and meat quality traits in Chinese red cattle (n = 224). Marker-trait association analyses showed that the HGD/PvuII genotypes showed a significant effect on meat cooking rate, muscle fiber diameter, and shear force (P < 0.05). The HGD DraIII genotypes showed a significant effect on muscle fiber diameter, shear force, and drip loss (P < 0.05). The HGD/AluI genotypes showed a significant effect on meat cooking rate, shear force, and drip loss (P < 0.05). The HGD/DraI genotypes showed a significant effect on meat cooking rate and shear force (P < 0.05). The HGD/EcoRV genotypes showed a significant effect on meat cooking rate, muscle fiber diameter, and shear force (P < 0.05). In all loci, no statistically significant differences were observed for pHu (P > 0.05). This is the first incidence where polymorphisms of a bovine HGD gene have demonstrated a correlation with meat traits in Chinese red cattle.
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Determination of the active site of Sphingobium chlorophenolicum 2,6-dichlorohydroquinone dioxygenase (PcpA). J Biol Inorg Chem 2009; 15:291-301. [DOI: 10.1007/s00775-009-0602-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 10/09/2009] [Indexed: 10/20/2022]
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Salicylate 1,2-Dioxygenase from Pseudaminobacter salicylatoxidans: Crystal Structure of a Peculiar Ring-cleaving Dioxygenase. J Mol Biol 2008; 380:856-68. [DOI: 10.1016/j.jmb.2008.05.041] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 05/13/2008] [Accepted: 05/18/2008] [Indexed: 11/24/2022]
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