1
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Gerlich G, Miller C, Yang X, Diviesti K, Bennett B, Klein-Seetharaman J, Holz RC. Catalytic role of histidine-114 in the hydrolytic dehalogenation of chlorothalonil by Pseudomonas sp. CTN-3. J Biol Inorg Chem 2024; 29:427-439. [PMID: 38796812 DOI: 10.1007/s00775-024-02053-1] [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: 10/20/2023] [Accepted: 02/19/2024] [Indexed: 05/29/2024]
Abstract
Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile; TPN) is an environmentally persistent fungicide that sees heavy use in the USA and is highly toxic to aquatic species and birds, as well as a probable human carcinogen. The chlorothalonil dehalogenase from Pseudomonas sp. CTN-3 (Chd, UniProtKB C9EBR5) degrades TPN to its less toxic 4-OH-TPN analog making it an exciting candidate for the development of a bioremediation process for TPN; however, little is currently known about its catalytic mechanism. Therefore, an active site residue histidine-114 (His114) which forms a hydrogen bond with the Zn(II)-bound water/hydroxide and has been suggested to be the active site acid/base, was substituted by an Ala residue. Surprisingly, ChdH114A exhibited catalytic activity with a kcat value of 1.07 s-1, ~ 5% of wild-type (WT) Chd, and a KM of 32 µM. Thus, His114 is catalytically important but not essential. The electronic and structural aspects of the WT Chd and ChdH114A active sites were examined using UV-Vis and EPR spectroscopy on the catalytically competent Co(II)-substituted enzyme as well as all-atomistic molecular dynamics (MD) simulations. Combination of these data suggest His114 can quickly and reversibly move nearly 2 Å between one conformation that facilitates catalysis and another that enables product egress and active site recharge. In light of experimental and computational data on ChdH114A, Asn216 appears to play a role in substrate binding and preorganization of the transition-state while Asp116 likely facilitates the deprotonation of the Zn(II)-bound water in the absence of His114. Based on these data, an updated proposed catalytic mechanism for Chd is presented.
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Affiliation(s)
- Grayson Gerlich
- Contribution from the Quantitative Biosciences and Engineering Program, Colorado School of Mines, Golden, CO, 80401, USA
- Department of Chemistry, Colorado School of Mines, Golden, CO, 80401, USA
| | - Callie Miller
- Department of Chemistry, Colorado School of Mines, Golden, CO, 80401, USA
| | - Xinhang Yang
- Department of Chemistry, Marquette University, Milwaukee, WI, 53233, USA
| | - Karla Diviesti
- Contribution from the Quantitative Biosciences and Engineering Program, Colorado School of Mines, Golden, CO, 80401, USA
- Department of Chemistry, Colorado School of Mines, Golden, CO, 80401, USA
| | - Brian Bennett
- Department of Physics, Marquette University, 1420 W. Clybourn St, Milwaukee, WI, 53233, USA.
| | | | - Richard C Holz
- Department of Chemistry, Colorado School of Mines, Golden, CO, 80401, USA.
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2
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Mazur M, Zych KM, Obmińska-Mrukowicz B, Pawlak A. Microbial Transformations of Halolactones and Evaluation of Their Antiproliferative Activity. Int J Mol Sci 2023; 24:ijms24087587. [PMID: 37108750 PMCID: PMC10144491 DOI: 10.3390/ijms24087587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
The microbial transformations of lactones with a halogenoethylocyclohexane moiety were performed in a filamentous fungi culture. The selected, effective biocatalyst for this process was the Absidia glauca AM177 strain. The lactones were transformed into the hydroxy derivative, regardless of the type of halogen atom in the substrate structure. For all lactones, the antiproliferative activity was determined toward several cancer cell lines. The antiproliferative potential of halolactones was much broader than that observed for the hydroxyderivative. According to the presented results, the most potent was chlorolactone, which exhibited significant activity toward the T-cell lymphoma line (CL-1) cell line. The hydroxyderivative obtained through biotransformation was not previously described in the literature.
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Affiliation(s)
- Marcelina Mazur
- Department of Food Chemistry and Biocatalysis, Wrocław University of Environmental and Life Sciences, Norwida 25, 50-375 Wrocław, Poland
| | - Karolina Maria Zych
- Department of Food Chemistry and Biocatalysis, Wrocław University of Environmental and Life Sciences, Norwida 25, 50-375 Wrocław, Poland
| | - Bożena Obmińska-Mrukowicz
- Department of Pharmacology and Toxicology, Wrocław University of Environmental and Life Sciences, C.K. Norwida 31, 50-375 Wrocław, Poland
| | - Aleksandra Pawlak
- Department of Pharmacology and Toxicology, Wrocław University of Environmental and Life Sciences, C.K. Norwida 31, 50-375 Wrocław, Poland
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3
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Fu Y, Liu X, Xia Y, Guo X, Guo J, Zhang J, Zhao W, Wu Y, Wang J, Zhong F. Whole-cell-catalyzed hydrogenation/deuteration of aryl halides with a genetically repurposed photodehalogenase. Chem 2023. [DOI: 10.1016/j.chempr.2023.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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4
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Dorner M, Lokesh S, Yang Y, Behrens S. Biochar-mediated abiotic and biotic degradation of halogenated organic contaminants - A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 852:158381. [PMID: 36055499 DOI: 10.1016/j.scitotenv.2022.158381] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/23/2022] [Accepted: 08/25/2022] [Indexed: 06/15/2023]
Abstract
Prevailing global increases in population, urbanization, and agricultural production are causing increased pressures on water resources, especially as the use of chemicals in agriculture, industry, and medicine provide new challenges for water treatment and reuse. Organohalogen compounds are persistent contaminants that often evade current wastewater treatment technologies, resulting in their accumulation in the environment and posing a serious threat to ecosystem health. Recent advances in understanding pyrogenic carbons as electron shuttling and storing materials have exposed their potential for enhancing the dehalogenation and overall degradation of organohalide contaminants in soil, sediment, surface water, and wastewater systems. Biochar is a porous carbonaceous material produced during the thermochemical decomposition of biomass feedstock in the presence of little or no oxygen (pyrolysis). Interest in biochar for application towards environmental remediation is largely based on its three distinct benefits: I) carbon sequestration to offset greenhouse gas emissions, II) adsorption of (in-) organic contaminants and nutrients, and III) a strong electron exchange capacity. Due to the innate complexity of biochar materials, several electron transfer mechanisms exist by which biochar may mediate contaminant degradation. These electron transfer pathways include electron-accepting and donating cycles through redox-active functional groups and direct electron transfer via conductive carbon matrices. These mechanisms are responsible for biochar's participation in multiple redox-driven biogeochemical transformations with proven consequences for effective organohalogen remediation. This literature review summarizes the current knowledge on the mechanisms and processes through which biochar can directly or indirectly mediate the transformation of organohalogen compounds under various environmental conditions. Perspectives and research directions for future application of biochars for targeted remediation strategies are also discussed.
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Affiliation(s)
- Mariah Dorner
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Srinidhi Lokesh
- Department of Civil and Environmental Engineering, University of Nevada, Reno, NV, USA
| | - Yu Yang
- Department of Civil and Environmental Engineering, University of Nevada, Reno, NV, USA
| | - Sebastian Behrens
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis, MN, USA; BioTechnology Institute, University of Minnesota, St. Paul, MN, USA.
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5
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Sarma H, Joshi SJ. Metagenomics Combined with Stable Isotope Probe (SIP) for the Discovery of Novel Dehalogenases Producing Bacteria. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 108:478-484. [PMID: 32978646 DOI: 10.1007/s00128-020-03004-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/16/2020] [Indexed: 06/11/2023]
Abstract
Halogenated compounds are one of the largest groups of environmental-hazardous chemicals. The removal of the halogen atom from the substrate is possible by the catalytic activity of a type of enzyme called dehalogenase. Hydrolytic dehalogenases are suggested to be a good biodegradation catalyst for halogenated compounds with potential bioremediation applications. Therefore, the identification of possible bacterial strains that produce dehalogenase is of great importance. Soil microorganisms that are regularly exposed to halogenated pesticides are a major source of hydrolytic dehalogenase. Their proper identification may be useful in the production of high-quality dehalogenase. DNA stable isotope probing (DNA-SIP) is quite a useful technique for the identification of active microorganisms that assimilate specific carbon substrates and nutrients. Metagenomics combined with a stable isotope probe (SIP) technique could therefore be used to detect bacterial dehalogenases in pesticides exposed agricultural soil.
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Affiliation(s)
- Hemen Sarma
- Department of Botany, N. N. Saikia College, Titabar, Assam, 785630, India.
| | - Sanket J Joshi
- Oil & Gas Research Center, Central Analytical and Applied Research Unit, Sultan Qaboos University, Muscat, Oman.
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6
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Molecular Cloning and Expression of Haloacid Dehalogenase Gene from a Local Pseudomonas aeruginosa ITB1 Strain and Tertiary Structure Prediction of the Produced Enzyme. JURNAL KIMIA SAINS DAN APLIKASI 2021. [DOI: 10.14710/jksa.24.5.161-169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Organohalogens are widely utilized as pesticides, herbicides, solvents, and for many other industrial purposes. However, the use of these compounds caused some negative impacts to the environment due to their toxicity and persistency. In the light of this, some microbes have been identified and employed to perform dehalogenation, converting halogenated organic compounds to non-toxic materials. In this research, we successfully cloned and sequenced the haloacid dehalogenase gene from a local Pseudomonas aeruginosa ITB1 strain, which is involved in the degradation of monochloroacetate. First, the haloacid dehalogenase gene was amplified by PCR using a pair of primers designed from the same gene sequences of other P. aeruginosa strains available in the GenBank. The cloned gene in pGEM-T in E. coli TOP10 was sequenced, analyzed, and then sub-cloned into pET-30a(+) for expression in E. coli BL21 (DE3). To facilitate direct sub-cloning, restriction sequences of EcoRI (G/AATTC) and HindIII (A/AGCTT) were added to the forward and reversed primers, respectively. The expressed protein in E. coli BL21 (DE3) appeared as a 26-kDa protein in SDS-PAGE analysis, which is in good agreement with the size predicted by ExPASy Protparam. We obtained that the best expression in LB liquid medium was achieved with 0.01 mM IPTG induction at 30°C incubation for 3 hours. We also found that the enzyme is more concentrated in the pellet cells as inclusion bodies. Furthermore, the in-silico analysis revealed that this enzyme consists of 233 amino acid residues. This enzyme’s predicted tertiary structure shows six β-sheets flanked by α-helixes and thus belongs to Group II haloacid dehalogenase. Based on the structural prediction, amino acid residues of Asp7, Ser121, and Asn122 are present in the active site and might play essential roles in catalysis. The presented study laid the foundation for recombinant haloacid dehalogenase production from P. aeruginosa local strains. It provided an insight into the utilization of recombinant local strains to remediate environmental problems caused by organohalogens.
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7
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Gul I, Le W, Jie Z, Ruiqin F, Bilal M, Tang L. Recent advances on engineered enzyme-conjugated biosensing modalities and devices for halogenated compounds. Trends Analyt Chem 2021. [DOI: 10.1016/j.trac.2020.116145] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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8
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Biotechnological Approach for the Production of Enantiomeric Hydroxylactones Derived from Benzaldehyde and Evaluation of Their Cytotoxic Activity. Catalysts 2020. [DOI: 10.3390/catal10111313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The β-aryl-δ-halo-γ-lactones are known for their antiproliferative activity towards numerous cancer cell lines. The aim of this study was to obtain in the biotransformation process new β-aryl-δ-hydroxy-γ-lactones and compare their activity with the antiproliferative activity of parent compounds. The racemic cis-5-(1-iodoethyl)-4-phenyldihydrofuran-2-one as well as separate enantiomers were transformed in fungal cultures. Among ten tested biocatalysts, three (Absidia cylindrospora AM336, Absidia glauca AM254, and Fusarium culmorum AM10) were able to catalyze the hydrolytic dehalogenation process. The biotransformations processes were highly stereoselective and enantiomerically pure hydroxylactones were obtained (ee ≥ 99%). The iodo- and hydroxylactone enantiomers were subjected to cytotoxic activity evaluation on canine leukemia and lymphoma cell lines. The iodolactones exhibited higher biological potential towards tested cell lines than hydroxylactones. Higher cytotoxic potential was also characteristic for (+)-(4S,5S,6R)-enantiomer of iodolactone compared to its antipode.
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9
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Gul I, Wang Q, Jiang Q, Fang R, Tang L. Enzyme immobilization on glass fiber membrane for detection of halogenated compounds. Anal Biochem 2020; 609:113971. [PMID: 32979368 DOI: 10.1016/j.ab.2020.113971] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 09/15/2020] [Accepted: 09/17/2020] [Indexed: 01/19/2023]
Abstract
Enzyme immobilization using inorganic membranes has enticed increased attention as they not only improve enzyme stability, but also furnish user-friendly biodevices that can be tailored to different applications. Herein, we explored the suitability of the glass fiber membrane for enzyme immobilization and its application for halocarbon detection. For this, halohydrin dehalogenase (HheC) and bovine serum albumin were crosslinked and immobilized on a glass fiber membrane without membrane functionalization. Immobilized HheC exhibited higher storage stability than its free counterpart over 60 days at 4 °C (67% immobilized vs. 8.1% free) and 30 °C (77% immobilized vs. 57% free). Similarly, the thermal endurance of the immobilized HheC was significantly improved. The practical utility of the membrane-immobilized enzyme was demonstrated by colorimetric detection of 1,3-dichloro-2-propanol (1,3-DCP) and 2,3-dibromo-1-propanol (2,3-DBP) as model analytes. Under optimized conditions, the detection limits of 0.06 mM and 0.09 mM were achieved for 1,3-DCP and 2,3-DBP, respectively. The satisfactory recoveries were observed with spiked river and lake water samples, which demonstrate the application potential of immobilized HheC for screening contaminants in water samples. Our results revealed that the proposed frugal and facile approach could be useful for enzyme stabilization, and mitigation of halocarbon pollution.
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Affiliation(s)
- Ijaz Gul
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Qian Wang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Qifa Jiang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Ruiqin Fang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China; Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Lixia Tang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China; Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu, 610054, China.
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10
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Structure-guided protein design of fluoroacetate dehalogenase for kinetic resolution of rac-2-bromobutyric acid. GREEN SYNTHESIS AND CATALYSIS 2020. [DOI: 10.1016/j.gresc.2020.05.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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11
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Catlin DS, Yang X, Bennett B, Holz RC, Liu D. Structural basis for the hydrolytic dehalogenation of the fungicide chlorothalonil. J Biol Chem 2020; 295:8668-8677. [PMID: 32358058 DOI: 10.1074/jbc.ra120.013150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 04/29/2020] [Indexed: 11/06/2022] Open
Abstract
Cleavage of aromatic carbon-chlorine bonds is critical for the degradation of toxic industrial compounds. Here, we solved the X-ray crystal structure of chlorothalonil dehalogenase (Chd) from Pseudomonas sp. CTN-3, with 15 of its N-terminal residues truncated (ChdT), using single-wavelength anomalous dispersion refined to 1.96 Å resolution. Chd has low sequence identity (<15%) compared with all other proteins whose structures are currently available, and to the best of our knowledge, we present the first structure of a Zn(II)-dependent aromatic dehalogenase that does not require a coenzyme. ChdT forms a "head-to-tail" homodimer, formed between two α-helices from each monomer, with three Zn(II)-binding sites, two of which occupy the active sites, whereas the third anchors a structural site at the homodimer interface. The catalytic Zn(II) ions are solvent-accessible via a large hydrophobic (8.5 × 17.8 Å) opening to bulk solvent and two hydrophilic branched channels. Each active-site Zn(II) ion resides in a distorted trigonal bipyramid geometry with His117, His257, Asp116, Asn216, and a water/hydroxide as ligands. A conserved His residue, His114, is hydrogen-bonded to the Zn(II)-bound water/hydroxide and likely functions as the general acid-base. We examined substrate binding by docking chlorothalonil (2,4,5,6-tetrachloroisophtalonitrile, TPN) into the hydrophobic channel and observed that the most energetically favorable pose includes a TPN orientation that coordinates to the active-site Zn(II) ions via a CN and that maximizes a π-π interaction with Trp227 On the basis of these results, along with previously reported kinetics data, we propose a refined catalytic mechanism for Chd-mediated TPN dehalogenation.
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Affiliation(s)
- Daniel S Catlin
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois, USA
| | - Xinhang Yang
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin, USA
| | - Brian Bennett
- Department of Physics, Marquette University, Milwaukee, Wisconsin, USA
| | - Richard C Holz
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin, USA; Department of Chemistry, Colorado School of Mines, Golden, Colorado, USA.
| | - Dali Liu
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois, USA.
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12
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Ni J, Liu Y, Shen C, Chen D, Xin Y, Liu Q. Bioinformatics, bacterial expression and enzyme activity analyses of dichloromethane dehalogenase from Methylobacterium rhodesianum H13. BIOTECHNOL BIOTEC EQ 2020. [DOI: 10.1080/13102818.2020.1818622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- Jianguo Ni
- Department of Environmental Engineering, College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, Zhejiang, PR China
- Department of Linpu Environmental Protection, Hangzhou Ecological Environment Bureau of Xiaoshan Branch, Hangzhou, Zhejiang, PR China
| | - Ying Liu
- Department of Environmental Engineering, College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, Zhejiang, PR China
| | - Chenjia Shen
- Department of Environmental Engineering, College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, Zhejiang, PR China
| | - Dongzhi Chen
- Department of Environmental Engineering, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang, PR China
| | - Yueyong Xin
- Department of Environmental Engineering, College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, Zhejiang, PR China
| | - Qi Liu
- Department of Environmental Engineering, College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, Zhejiang, PR China
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13
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Calderini E, Wessel J, Süss P, Schrepfer P, Wardenga R, Schallmey A. Selective Ring‐Opening of Di‐Substituted Epoxides Catalysed by Halohydrin Dehalogenases. ChemCatChem 2019. [DOI: 10.1002/cctc.201900103] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Elia Calderini
- Institute for Biochemistry, Biotechnology and BioinformaticsTechnische Universität Braunschweig Spielmannstr. 7 38106 Braunschweig Germany
| | - Julia Wessel
- Institute for Biochemistry, Biotechnology and BioinformaticsTechnische Universität Braunschweig Spielmannstr. 7 38106 Braunschweig Germany
| | - Philipp Süss
- Enzymicals AG Walther-Rathenau-Straße 49A 17489 Greifswald Germany
| | - Patrick Schrepfer
- Institute for Biochemistry, Biotechnology and BioinformaticsTechnische Universität Braunschweig Spielmannstr. 7 38106 Braunschweig Germany
| | - Rainer Wardenga
- Enzymicals AG Walther-Rathenau-Straße 49A 17489 Greifswald Germany
| | - Anett Schallmey
- Institute for Biochemistry, Biotechnology and BioinformaticsTechnische Universität Braunschweig Spielmannstr. 7 38106 Braunschweig Germany
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14
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Adak S, Begley TP. Hexachlorobenzene Catabolism Involves a Nucleophilic Aromatic Substitution and Flavin-N5-Oxide Formation. Biochemistry 2019; 58:1181-1183. [DOI: 10.1021/acs.biochem.9b00012] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sanjoy Adak
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
| | - Tadhg P. Begley
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
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15
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Roles of Two Glutathione-Dependent 3,6-Dichlorogentisate Dehalogenases in Rhizorhabdus dicambivorans Ndbn-20 in the Catabolism of the Herbicide Dicamba. Appl Environ Microbiol 2018; 84:AEM.00623-18. [PMID: 29934333 DOI: 10.1128/aem.00623-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/18/2018] [Indexed: 11/20/2022] Open
Abstract
The herbicide dicamba is initially demethylated to 3,6-dichlorosalicylate (3,6-DCSA) in Rhizorhabdus dicambivorans Ndbn-20 and is subsequently 5-hydroxylated to 3,6-dichlorogentisate (3,6-DCGA). In the present study, two glutathione-dependent 3,6-DCGA dehalogenases, DsmH1 and DsmH2, were identified in strain Ndbn-20. DsmH2 shared a low identity (only 31%) with the tetrachlorohydroquinone (TCHQ) dehalogenase PcpC from Sphingobium chlorophenolicum ATCC 39723, while DsmH1 shared a high identity (79%) with PcpC. In the phylogenetic tree of related glutathione S-transferases (GSTs), DsmH1 and DsmH2, together with PcpC and the 2,5-dichlorohydroquinone dehalogenase LinD, formed a separate clade. DsmH1 and DsmH2 were synthesized in Escherichia coli BL21 and purified as His-tagged enzymes. Both enzymes required glutathione (GSH) as a cofactor and could 6-dechlorinate 3,6-DCGA to 3-chlorogentisate in vitro DsmH2 had a significantly higher catalytic efficiency toward 3,6-DCGA than DsmH1. Transcription and disruption analysis revealed that DsmH2 but not DsmH1 was responsible for the 6-dechlorination of 3,6-DCGA in strain Ndbn-20 in vivo Furthermore, we propose a novel eta class of GSTs to accommodate the four bacterial dehalogenases PcpC, LinD, DsmH1, and DsmH2.IMPORTANCE Dicamba is an important herbicide, and its use and leakage into the environment have dramatically increased since the large-scale planting of genetically modified (GM) dicamba-resistant crops in 2015. However, the complete catabolic pathway of dicamba has remained unknown, which limits ecotoxicological studies of this herbicide. Our previous study revealed that 3,6-DCGA was an intermediate of dicamba degradation in strain Ndbn-20. In this study, we identified two glutathione-dependent 3,6-DCGA dehalogenases, DsmH1 and DsmH2, and demonstrated that DsmH2 is physiologically responsible for the 6-dechlorination of 3,6-DCGA in strain Ndbn-20. GSTs play an important role in the detoxification and degradation of a variety of endogenous and exogenous toxic compounds. On the basis of their sequence identities, phylogenetic status, and functions, the four bacterial GSH-dependent dehalogenases (PcpC, LinD, DsmH1, and DsmH2) were reclassified as a new eta class of GSTs. This study helps us to elucidate the microbial catabolism of dicamba and enhances our understanding of the diversity and functions of GSTs.
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16
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Dai Y, Valentino H, Sobrado P. Evidence for the Formation of a Radical-Mediated Flavin-N5 Covalent Intermediate. Chembiochem 2018; 19:1609-1612. [PMID: 29776001 DOI: 10.1002/cbic.201800123] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Indexed: 01/07/2023]
Abstract
The redox-neutral reaction catalyzed by 2-haloacrylate hydratase (2-HAH) leads to the conversion of 2-chloroacrylate to pyruvate. Previous mechanistic studies demonstrated the formation of a flavin-iminium ion as an important intermediate in the 2-HAH catalytic cycle. Time-resolved flavin absorbance studies were performed in this study, and the data showed that the enzyme is capable of stabilizing both anionic and neutral flavin semiquinone species. The presence of a radical scavenger decreases the activity in a concentration-dependent manner. These data are consistent with the flavin iminium intermediate occurring by radical recombination.
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Affiliation(s)
- Yumin Dai
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, 360 West Campus Drive, Blacksburg, VA, 24061, USA
| | - Hannah Valentino
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, 360 West Campus Drive, Blacksburg, VA, 24061, USA
| | - Pablo Sobrado
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, 360 West Campus Drive, Blacksburg, VA, 24061, USA
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17
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Tiedt O, Fuchs J, Eisenreich W, Boll M. A catalytically versatile benzoyl-CoA reductase, key enzyme in the degradation of methyl- and halobenzoates in denitrifying bacteria. J Biol Chem 2018; 293:10264-10274. [PMID: 29769313 DOI: 10.1074/jbc.ra118.003329] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 05/15/2018] [Indexed: 12/22/2022] Open
Abstract
Class I benzoyl-CoA (BzCoA) reductases (BCRs) are key enzymes in the anaerobic degradation of aromatic compounds. They catalyze the ATP-dependent reduction of the central BzCoA intermediate and analogues of it to conjugated cyclic 1,5-dienoyl-CoAs probably by a radical-based, Birch-like reduction mechanism. Discovered in 1995, the enzyme from the denitrifying bacterium Thauera aromatica (BCRTar) has so far remained the only isolated and biochemically accessible BCR, mainly because BCRs are extremely labile, and their heterologous production has largely failed so far. Here, we describe a platform for the heterologous expression of the four structural genes encoding a designated 3-methylbenzoyl-CoA reductase from the related denitrifying species Thauera chlorobenzoica (MBRTcl) in Escherichia coli This reductase represents the prototype of a distinct subclass of ATP-dependent BCRs that were proposed to be involved in the degradation of methyl-substituted BzCoA analogues. The recombinant MBRTcl had an αβγδ-subunit architecture, contained three low-potential [4Fe-4S] clusters, and was highly oxygen-labile. It catalyzed the ATP-dependent reductive dearomatization of BzCoA with 2.3-2.8 ATPs hydrolyzed per two electrons transferred and preferentially dearomatized methyl- and chloro-substituted analogues in meta- and para-positions. NMR analyses revealed that 3-methylbenzoyl-CoA is regioselectively reduced to 3-methyl-1,5-dienoyl-CoA. The unprecedented reductive dechlorination of 4-chloro-BzCoA to BzCoA probably via HCl elimination from a reduced intermediate allowed for the previously unreported growth of T. chlorobenzoica on 4-chlorobenzoate. The heterologous expression platform established in this work enables the production, isolation, and characterization of bacterial and archaeal BCR and BCR-like radical enzymes, for many of which the function has remained unknown.
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Affiliation(s)
- Oliver Tiedt
- From the Fakultät für Biologie-Mikrobiologie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany and
| | - Jonathan Fuchs
- From the Fakultät für Biologie-Mikrobiologie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany and
| | - Wolfgang Eisenreich
- Lehrstuhl für Biochemie, Technische Universität München, 85747 Garching, Germany
| | - Matthias Boll
- From the Fakultät für Biologie-Mikrobiologie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany and
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Ang TF, Maiangwa J, Salleh AB, Normi YM, Leow TC. Dehalogenases: From Improved Performance to Potential Microbial Dehalogenation Applications. Molecules 2018; 23:E1100. [PMID: 29735886 PMCID: PMC6100074 DOI: 10.3390/molecules23051100] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/07/2018] [Accepted: 04/09/2018] [Indexed: 11/16/2022] Open
Abstract
The variety of halogenated substances and their derivatives widely used as pesticides, herbicides and other industrial products is of great concern due to the hazardous nature of these compounds owing to their toxicity, and persistent environmental pollution. Therefore, from the viewpoint of environmental technology, the need for environmentally relevant enzymes involved in biodegradation of these pollutants has received a great boost. One result of this great deal of attention has been the identification of environmentally relevant bacteria that produce hydrolytic dehalogenases—key enzymes which are considered cost-effective and eco-friendly in the removal and detoxification of these pollutants. These group of enzymes catalyzing the cleavage of the carbon-halogen bond of organohalogen compounds have potential applications in the chemical industry and bioremediation. The dehalogenases make use of fundamentally different strategies with a common mechanism to cleave carbon-halogen bonds whereby, an active-site carboxylate group attacks the substrate C atom bound to the halogen atom to form an ester intermediate and a halide ion with subsequent hydrolysis of the intermediate. Structurally, these dehalogenases have been characterized and shown to use substitution mechanisms that proceed via a covalent aspartyl intermediate. More so, the widest dehalogenation spectrum of electron acceptors tested with bacterial strains which could dehalogenate recalcitrant organohalides has further proven the versatility of bacterial dehalogenators to be considered when determining the fate of halogenated organics at contaminated sites. In this review, the general features of most widely studied bacterial dehalogenases, their structural properties, basis of the degradation of organohalides and their derivatives and how they have been improved for various applications is discussed.
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Affiliation(s)
- Thiau-Fu Ang
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Enzyme and Microbial Technology Research Centre, Centre of Excellence, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
| | - Jonathan Maiangwa
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Enzyme and Microbial Technology Research Centre, Centre of Excellence, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
| | - Abu Bakar Salleh
- Enzyme and Microbial Technology Research Centre, Centre of Excellence, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Institute of Bioscience, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
| | - Yahaya M Normi
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Enzyme and Microbial Technology Research Centre, Centre of Excellence, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
| | - Thean Chor Leow
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Enzyme and Microbial Technology Research Centre, Centre of Excellence, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Institute of Bioscience, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
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Manna RN, Grzybkowska A, Gelman F, Dybala-Defratyka A. Carbon-bromine bond cleavage - A perspective from bromine and carbon kinetic isotope effects on model debromination reactions. CHEMOSPHERE 2018; 193:17-23. [PMID: 29126061 DOI: 10.1016/j.chemosphere.2017.10.153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 10/13/2017] [Accepted: 10/27/2017] [Indexed: 06/07/2023]
Abstract
In this work, we explore the effect of solvent on 13C and 81Br kinetic isotope effects (KIEs) during elimination of bromine substituent from brominated organic compounds promoted by hydroxyl anion. In the present study, we investigate HBr elimination from 2-bromoethylbenzene in three different polar media (water, ethanol, and acetonitrile) as well as bromide ion elimination from 1,2-dibromoethane upon nucleophilic substitution by the hydroxyl ion in aqueous solution using carbon and bromine isotope analysis as mechanistic tools. We reconsider the hypothesis that the magnitude of leaving group halide KIE should visibly depend on the solvent and bond-breaking in a protic solvent should be accompanied by hydrogen bonding which would result in less zero-point energy loss than in an aprotic solvent. Modeling the elimination reaction using the available popular theoretical methods along with different approaches for including environment effects we demonstrate in the presented study no interpretable effect of the solvent on the transition state structure and hence on the theoretically predicted KIEs. The comparison of the magnitudes of carbon and bromine kinetic isotope effects for two different mechanistic pathways (elimination vs substitution) is also discussed.
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Affiliation(s)
- Rabindra Nath Manna
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland; Indian Association for the Cultivation of Science, Physical Chemistry, 2A and 2B Raja S C Mullick Road, Kolkata, West Bengal, 700032, India
| | - Anna Grzybkowska
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
| | - Faina Gelman
- Geological Survey of Israel, Malkhei Israel St. 30, 95501 Jerusalem, Israel
| | - Agnieszka Dybala-Defratyka
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland.
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20
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Wang JB, Ilie A, Yuan S, Reetz MT. Investigating Substrate Scope and Enantioselectivity of a Defluorinase by a Stereochemical Probe. J Am Chem Soc 2017; 139:11241-11247. [DOI: 10.1021/jacs.7b06019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Jian-bo Wang
- Department
of Chemistry, Philipps-University, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Muelheim, Germany
| | - Adriana Ilie
- Department
of Chemistry, Philipps-University, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Muelheim, Germany
| | - Shuguang Yuan
- Laboratory
of Physical Chemistry of Polymers and Membranes, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH B3 495 (Bâtiment CH) Station
6, CH-1015 Lausanne, Switzerland
| | - Manfred T. Reetz
- Department
of Chemistry, Philipps-University, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Muelheim, Germany
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21
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Tang X, Wang J, Zhao N, Zhang Q, Wang W. Theoretical study on the hydrolytic step in the biotransformation of β-hexachlorocyclohexane degraded by haloalkane dehalogenase LinB. CAN J CHEM 2017. [DOI: 10.1139/cjc-2016-0653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The hydrolytic process of LinB-catalyzed biotransformation of a notorious contaminant β-HCH was investigated in atomistic detail with a combined quantum mechanics/molecular mechanics approach. The Boltzmann-weighted averaging method amended by disproportionate effect analysis was showed to capture the fluctuation of a single molecule enzyme reaction. With the potential barriers of 18.7 and 2.6 kcal/mol, two elementary steps that refer to formation and decomposition of a tetrahedral intermediate are involved in the hydrolytic reaction, respectively. Polarized by Glu132, His272 serves as a proton carrier along the whole hydrolysis reaction. The electrostatic influence analysis highlighted residue Leu248 as a possible mutation target for rational design of LinB in enzyme modification. Further spatial location analysis provided explanation for the opposite effect of Asn38 toward the two elementary steps. Getting insight into the catalytic details and the structure and function of LinB can enrich the knowledge of it and promote its application in bioremediation of chlorinated hydrocarbon pollutants.
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Affiliation(s)
- Xiaowen Tang
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
| | - Junjie Wang
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
| | - Nan Zhao
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
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22
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Agarwal V, Miles ZD, Winter JM, Eustáquio AS, El Gamal AA, Moore BS. Enzymatic Halogenation and Dehalogenation Reactions: Pervasive and Mechanistically Diverse. Chem Rev 2017; 117:5619-5674. [PMID: 28106994 PMCID: PMC5575885 DOI: 10.1021/acs.chemrev.6b00571] [Citation(s) in RCA: 249] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Naturally produced halogenated compounds are ubiquitous across all domains of life where they perform a multitude of biological functions and adopt a diversity of chemical structures. Accordingly, a diverse collection of enzyme catalysts to install and remove halogens from organic scaffolds has evolved in nature. Accounting for the different chemical properties of the four halogen atoms (fluorine, chlorine, bromine, and iodine) and the diversity and chemical reactivity of their organic substrates, enzymes performing biosynthetic and degradative halogenation chemistry utilize numerous mechanistic strategies involving oxidation, reduction, and substitution. Biosynthetic halogenation reactions range from simple aromatic substitutions to stereoselective C-H functionalizations on remote carbon centers and can initiate the formation of simple to complex ring structures. Dehalogenating enzymes, on the other hand, are best known for removing halogen atoms from man-made organohalogens, yet also function naturally, albeit rarely, in metabolic pathways. This review details the scope and mechanism of nature's halogenation and dehalogenation enzymatic strategies, highlights gaps in our understanding, and posits where new advances in the field might arise in the near future.
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Affiliation(s)
- Vinayak Agarwal
- Center for Oceans and Human Health, Scripps Institution of Oceanography, University of California, San Diego
| | - Zachary D. Miles
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego
| | | | - Alessandra S. Eustáquio
- College of Pharmacy, Department of Medicinal Chemistry & Pharmacognosy and Center for Biomolecular Sciences, University of Illinois at Chicago
| | - Abrahim A. El Gamal
- Center for Oceans and Human Health, Scripps Institution of Oceanography, University of California, San Diego
| | - Bradley S. Moore
- Center for Oceans and Human Health, Scripps Institution of Oceanography, University of California, San Diego
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego
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23
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Adamu A, Shamsir MS, Wahab RA, Parvizpour S, Huyop F. Multi-template homology-based structural model of L-2-haloacid dehalogenase (DehL) from Rhizobium sp. RC1. J Biomol Struct Dyn 2016; 35:3285-3296. [DOI: 10.1080/07391102.2016.1254115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Aliyu Adamu
- Faculty of Biosciences and Medical Engineering, Department of Biotechnology and Medical Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310, Johor, Malaysia
- Faculty of Science, Department of Microbiology, Kaduna State University, Tafawa Balewa way, Kaduna PMB 2339, Nigeria
| | - Mohd Shahir Shamsir
- Faculty of Biosciences and Medical Engineering, Department of Biotechnology and Medical Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310, Johor, Malaysia
| | - Roswanira Abdul Wahab
- Faculty of Science, Department of Chemistry, Universiti Teknologi Malaysia, Johor Bahru 81310, Johor, Malaysia
| | - Sepideh Parvizpour
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Fahrul Huyop
- Faculty of Biosciences and Medical Engineering, Department of Biotechnology and Medical Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310, Johor, Malaysia
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24
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Marcos V, Stephens AJ, Jaramillo-Garcia J, Nussbaumer AL, Woltering SL, Valero A, Lemonnier JF, Vitorica-Yrezabal IJ, Leigh DA. Allosteric initiation and regulation of catalysis with a molecular knot. Science 2016; 352:1555-9. [DOI: 10.1126/science.aaf3673] [Citation(s) in RCA: 167] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 05/17/2016] [Indexed: 12/24/2022]
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25
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Properties and biotechnological applications of natural and engineered haloalkane dehalogenases. Appl Microbiol Biotechnol 2015; 99:9865-81. [DOI: 10.1007/s00253-015-6954-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 08/19/2015] [Accepted: 08/22/2015] [Indexed: 01/01/2023]
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26
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Reductive dehalogenation of 3,5-dibromo-4-hydroxybenzoate by an aerobic strain of Delftia sp. EOB-17. Biotechnol Lett 2015; 37:2395-401. [DOI: 10.1007/s10529-015-1932-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/04/2015] [Indexed: 11/25/2022]
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27
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Tanaka S, Mochizuki Y, Komeiji Y, Okiyama Y, Fukuzawa K. Electron-correlated fragment-molecular-orbital calculations for biomolecular and nano systems. Phys Chem Chem Phys 2015; 16:10310-44. [PMID: 24740821 DOI: 10.1039/c4cp00316k] [Citation(s) in RCA: 189] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent developments in the fragment molecular orbital (FMO) method for theoretical formulation, implementation, and application to nano and biomolecular systems are reviewed. The FMO method has enabled ab initio quantum-mechanical calculations for large molecular systems such as protein-ligand complexes at a reasonable computational cost in a parallelized way. There have been a wealth of application outcomes from the FMO method in the fields of biochemistry, medicinal chemistry and nanotechnology, in which the electron correlation effects play vital roles. With the aid of the advances in high-performance computing, the FMO method promises larger, faster, and more accurate simulations of biomolecular and related systems, including the descriptions of dynamical behaviors in solvent environments. The current status and future prospects of the FMO scheme are addressed in these contexts.
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Affiliation(s)
- Shigenori Tanaka
- Graduate School of System Informatics, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.
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28
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Reductive dehalogenase structure suggests a mechanism for B12-dependent dehalogenation. Nature 2014; 517:513-516. [PMID: 25327251 PMCID: PMC4968649 DOI: 10.1038/nature13901] [Citation(s) in RCA: 196] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 09/30/2014] [Indexed: 11/08/2022]
Abstract
Organohalide chemistry underpins many industrial and agricultural processes, and a large proportion of environmental pollutants are organohalides. Nevertheless, organohalide chemistry is not exclusively of anthropogenic origin, with natural abiotic and biological processes contributing to the global halide cycle. Reductive dehalogenases are responsible for biological dehalogenation in organohalide respiring bacteria, with substrates including polychlorinated biphenyls or dioxins. Reductive dehalogenases form a distinct subfamily of cobalamin (B12)-dependent enzymes that are usually membrane associated and oxygen sensitive, hindering detailed studies. Here we report the characterization of a soluble, oxygen-tolerant reductive dehalogenase and, by combining structure determination with EPR (electron paramagnetic resonance) spectroscopy and simulation, show that a direct interaction between the cobalamin cobalt and the substrate halogen underpins catalysis. In contrast to the carbon-cobalt bond chemistry catalysed by the other cobalamin-dependent subfamilies, we propose that reductive dehalogenases achieve reduction of the organohalide substrate via halogen-cobalt bond formation. This presents a new model in both organohalide and cobalamin (bio)chemistry that will guide future exploitation of these enzymes in bioremediation or biocatalysis.
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29
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Expanding the Halohydrin Dehalogenase Enzyme Family: Identification of Novel Enzymes by Database Mining. Appl Environ Microbiol 2014; 80:7303-15. [PMID: 25239895 DOI: 10.1128/aem.01985-14] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 09/13/2014] [Indexed: 01/22/2023] Open
Abstract
Halohydrin dehalogenases are very rare enzymes that are naturally involved in the mineralization of halogenated xenobiotics. Due to their catalytic potential and promiscuity, many biocatalytic reactions have been described that have led to several interesting and industrially important applications. Nevertheless, only a few of these enzymes have been made available through recombinant techniques; hence, it is of general interest to expand the repertoire of these enzymes so as to enable novel biocatalytic applications. After the identification of specific sequence motifs, 37 novel enzyme sequences were readily identified in public sequence databases. All enzymes that could be heterologously expressed also catalyzed typical halohydrin dehalogenase reactions. Phylogenetic inference for enzymes of the halohydrin dehalogenase enzyme family confirmed that all enzymes form a distinct monophyletic clade within the short-chain dehydrogenase/reductase superfamily. In addition, the majority of novel enzymes are substantially different from previously known phylogenetic subtypes. Consequently, four additional phylogenetic subtypes were defined, greatly expanding the halohydrin dehalogenase enzyme family. We show that the enormous wealth of environmental and genome sequences present in public databases can be tapped for in silico identification of very rare but biotechnologically important biocatalysts. Our findings help to readily identify halohydrin dehalogenases in ever-growing sequence databases and, as a consequence, make even more members of this interesting enzyme family available to the scientific and industrial community.
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30
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A Mechanistic Analysis of Enzymatic Degradation of Organohalogen Compounds. Biosci Biotechnol Biochem 2014; 75:189-98. [DOI: 10.1271/bbb.100746] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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31
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Role of Dehalogenases in Aerobic Bacterial Degradation of Chlorinated Aromatic Compounds. J CHEM-NY 2014. [DOI: 10.1155/2014/157974] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
This review was conducted to provide an overview of dehalogenases involved in aerobic biodegradation of chlorinated aromatic compounds. Additionally, biochemical and molecular characterization of hydrolytic, reductive, and oxygenolytic dehalogenases was reviewed. This review will increase our understanding of the process of dehalogenation of chlorinated aromatic compounds.
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32
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Chen K, Huang L, Xu C, Liu X, He J, Zinder SH, Li S, Jiang J. Molecular characterization of the enzymes involved in the degradation of a brominated aromatic herbicide. Mol Microbiol 2013; 89:1121-39. [PMID: 23859214 DOI: 10.1111/mmi.12332] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2013] [Indexed: 11/26/2022]
Abstract
Dehalogenation is the key step in the degradation of halogenated aromatics, while reductive dehalogenation is originally thought to rarely occur in aerobes. In this study, an aerobic strain of Comamonas sp. 7D-2 was shown to degrade the brominated aromatic herbicide bromoxynil completely and release two equivalents of bromides under aerobic conditions. The enzymes involved in the degradation of bromoxynil to 4-carboxy-2-hydroxymuconate-6-semialdehyde, including nitrilase, reductive dehalogenase (BhbA), 4-hydroxybenzoate 3-monooxygenase and protocatechuate 4,5-dioxygenase, were molecularly characterized. The novel dehalogenase BhbA was shown to be a complex of a respiration-linked reductive dehalogenase (RdhA) domain and a NAD(P)H-dependent oxidoreductase domain and to have key features of anaerobic respiratory RdhAs, including two predicted binding motifs for [4Fe-4S] clusters and a close association with a hydrophobic membrane protein (BhbB). BhbB was confirmed to anchor BhbA to the membrane. BhbA was partially purified and found to use NAD(P)H as electron donors. Full-length bhbA homologues were found almost exclusively in marine aerobic proteobacteria, suggesting that reductive dehalogenation occurs extensively in aerobes and that bhbA is horizontally transferred from marine microorganisms. The discovery of a functional reductive dehalogenase and ring-cleavage oxygenases in an aerobe opens up possibilities for basic research as well as the potential application for bioremediation.
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Affiliation(s)
- Kai Chen
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095, Nanjing, China
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Herschlag D, Natarajan A. Fundamental challenges in mechanistic enzymology: progress toward understanding the rate enhancements of enzymes. Biochemistry 2013; 52:2050-67. [PMID: 23488725 DOI: 10.1021/bi4000113] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enzymes are remarkable catalysts that lie at the heart of biology, accelerating chemical reactions to an astounding extent with extraordinary specificity. Enormous progress in understanding the chemical basis of enzymatic transformations and the basic mechanisms underlying rate enhancements over the past decades is apparent. Nevertheless, it has been difficult to achieve a quantitative understanding of how the underlying mechanisms account for the energetics of catalysis, because of the complexity of enzyme systems and the absence of underlying energetic additivity. We review case studies from our own work that illustrate the power of precisely defined and clearly articulated questions when dealing with such complex and multifaceted systems, and we also use this approach to evaluate our current ability to design enzymes. We close by highlighting a series of questions that help frame some of what remains to be understood, and we encourage the reader to define additional questions and directions that will deepen and broaden our understanding of enzymes and their catalysis.
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Affiliation(s)
- Daniel Herschlag
- Department of Biochemistry, Stanford University School of Medicine , Stanford, California 94305, United States
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34
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Nikel PI, Pérez-Pantoja D, de Lorenzo V. Why are chlorinated pollutants so difficult to degrade aerobically? Redox stress limits 1,3-dichloroprop-1-ene metabolism by Pseudomonas pavonaceae. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120377. [PMID: 23479756 DOI: 10.1098/rstb.2012.0377] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Chlorinated pollutants are hardly biodegradable under oxic conditions, but they can often be metabolized by anaerobic bacteria through organohalide respiration reactions. In an attempt to identify bottlenecks limiting aerobic catabolism of 1,3-dichloroprop-1-ene (1,3-DCP; a widely used organohalide) in Pseudomonas pavonaceae, the possible physiological restrictions for this process were surveyed. Flow cytometry and a bioluminescence reporter of metabolic state revealed that cells treated with 1,3-DCP experienced an intense stress that could be traced to the endogenous production of reactive oxygen species (ROS) during the metabolism of the compound. Cells exposed to 1,3-DCP also manifested increased levels of D-glucose-6-P 1-dehydrogenase activity (G6PDH, an enzyme key to the synthesis of reduced NADPH), observed under both glycolytic and gluconeogenic growth regimes. The increase in G6PDH activity, as well as cellular hydroperoxide levels, correlated with the generation of ROS. Additionally, the high G6PDH activity was paralleled by the accumulation of D-glucose-6-P, suggesting a metabolic flux shift that favours the production of NADPH. Thus, G6PDH and its cognate substrate seem to play an important role in P. pavonaceae under redox stress caused by 1,3-DCP, probably by increasing the rate of NADPH turnover. The data suggest that oxidative stress associated with the biodegradation of 1,3-DCP reflects a significant barrier for the evolution of aerobic pathways for chlorinated compounds, thereby allowing for the emergence of anaerobic counterparts.
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Affiliation(s)
- Pablo I Nikel
- Systems and Synthetic Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Madrid 28049, Spain
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Nikel PI, de Lorenzo V. Engineering an anaerobic metabolic regime in Pseudomonas putida KT2440 for the anoxic biodegradation of 1,3-dichloroprop-1-ene. Metab Eng 2013; 15:98-112. [DOI: 10.1016/j.ymben.2012.09.006] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 09/21/2012] [Indexed: 11/29/2022]
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Arif MI, Samin G, van Leeuwen JGE, Oppentocht J, Janssen DB. Novel dehalogenase mechanism for 2,3-dichloro-1-propanol utilization in Pseudomonas putida strain MC4. Appl Environ Microbiol 2012; 78:6128-36. [PMID: 22752160 PMCID: PMC3416625 DOI: 10.1128/aem.00760-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 06/14/2012] [Indexed: 11/20/2022] Open
Abstract
A Pseudomonas putida strain (MC4) that can utilize 2,3-dichloro-1-propanol (DCP) and several aliphatic haloacids and haloalcohols as sole carbon and energy source for growth was isolated from contaminated soil. Degradation of DCP was found to start with oxidation and concomitant dehalogenation catalyzed by a 72-kDa monomeric protein (DppA) that was isolated from cell lysate. The dppA gene was cloned from a cosmid library and appeared to encode a protein equipped with a signal peptide and that possessed high similarity to quinohemoprotein alcohol dehydrogenases (ADHs), particularly ADH IIB and ADH IIG from Pseudomonas putida HK. This novel dehalogenating dehydrogenase has a broad substrate range, encompassing a number of nonhalogenated alcohols and haloalcohols. With DCP, DppA exhibited a k(cat) of 17 s(-1). (1)H nuclear magnetic resonance experiments indicated that DCP oxidation by DppA in the presence of 2,6-dichlorophenolindophenol (DCPIP) and potassium ferricyanide [K(3)Fe(CN)(6)] yielded 2-chloroacrolein, which was oxidized to 2-chloroacrylic acid.
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Affiliation(s)
- Muhammad Irfan Arif
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
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Biedermannová L, Prokop Z, Gora A, Chovancová E, Kovács M, Damborsky J, Wade RC. A single mutation in a tunnel to the active site changes the mechanism and kinetics of product release in haloalkane dehalogenase LinB. J Biol Chem 2012; 287:29062-74. [PMID: 22745119 DOI: 10.1074/jbc.m112.377853] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many enzymes have buried active sites. The properties of the tunnels connecting the active site with bulk solvent affect ligand binding and unbinding and also the catalytic properties. Here, we investigate ligand passage in the haloalkane dehalogenase enzyme LinB and the effect of replacing leucine by a bulky tryptophan at a tunnel-lining position. Transient kinetic experiments show that the mutation significantly slows down the rate of product release. Moreover, the mechanism of bromide ion release is changed from a one-step process in the wild type enzyme to a two-step process in the mutant. The rate constant of bromide ion release corresponds to the overall steady-state turnover rate constant, suggesting that product release became the rate-limiting step of catalysis in the mutant. We explain the experimental findings by investigating the molecular details of the process computationally. Analysis of trajectories from molecular dynamics simulations with a tunnel detection software reveals differences in the tunnels available for ligand egress. Corresponding differences are seen in simulations of product egress using a specialized enhanced sampling technique. The differences in the free energy barriers for egress of a bromide ion obtained using potential of mean force calculations are in good agreement with the differences in rates obtained from the transient kinetic experiments. Interactions of the bromide ion with the introduced tryptophan are shown to affect the free energy barrier for its passage. The study demonstrates how the mechanism of an enzymatic catalytic cycle and reaction kinetics can be engineered by modification of protein tunnels.
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Affiliation(s)
- Lada Biedermannová
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg, Germany.
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Thibodeaux CJ, Chang WC, Liu HW. Enzymatic chemistry of cyclopropane, epoxide, and aziridine biosynthesis. Chem Rev 2012; 112:1681-709. [PMID: 22017381 PMCID: PMC3288687 DOI: 10.1021/cr200073d] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Wei-chen Chang
- College of Pharmacy and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Hung-wen Liu
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- College of Pharmacy and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
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Identification of the role of C/EBP in neurite regeneration following microarray analysis of a L. stagnalis CNS injury model. BMC Neurosci 2012; 13:2. [PMID: 22217148 PMCID: PMC3315421 DOI: 10.1186/1471-2202-13-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 01/04/2012] [Indexed: 12/02/2022] Open
Abstract
Background Neuronal regeneration in the adult mammalian central nervous system (CNS) is severely compromised due to the presence of extrinsic inhibitory signals and a reduced intrinsic regenerative capacity. In contrast, the CNS of adult Lymnaea stagnalis (L. stagnalis), a freshwater pond snail, is capable of spontaneous regeneration following neuronal injury. Thus, L. stagnalis has served as an animal model to study the cellular mechanisms underlying neuronal regeneration. However, the usage of this model has been limited due to insufficient molecular tools. We have recently conducted a partial neuronal transcriptome sequencing project and reported over 10,000 EST sequences which allowed us to develop and perform a large-scale high throughput microarray analysis. Results To identify genes that are involved in the robust regenerative capacity observed in L. stagnalis, we designed the first gene chip covering ~15, 000 L. stagnalis CNS EST sequences. We conducted microarray analysis to compare the gene expression profiles of sham-operated (control) and crush-operated (regenerative model) central ganglia of adult L. stagnalis. The expression levels of 348 genes were found to be significantly altered (p < 0.05) following nerve injury. From this pool, 67 sequences showed a greater than 2-fold change: 42 of which were up-regulated and 25 down-regulated. Our qPCR analysis confirmed that CCAAT enhancer binding protein (C/EBP) was up-regulated following nerve injury in a time-dependent manner. In order to test the role of C/EBP in regeneration, C/EBP siRNA was applied following axotomy of cultured Lymnaea PeA neurons. Knockdown of C/EBP following axotomy prevented extension of the distal, proximal and intact neurites. In vivo knockdown of C/EBP postponed recovery of locomotory activity following nerve crush. Taken together, our data suggest both somatic and local effects of C/EBP are involved in neuronal regeneration. Conclusions This is the first high-throughput microarray study in L. stagnalis, a model of axonal regeneration following CNS injury. We reported that 348 genes were regulated following central nerve injury in adult L. stagnalis and provided the first evidence for the involvement of local C/EBP in neuronal regeneration. Our study demonstrates the usefulness of the large-scale gene profiling approach in this invertebrate model to study the molecular mechanisms underlying the intrinsic regenerative capacity of adult CNS neurons.
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Chan PWY, Yakunin AF, Edwards EA, Pai EF. Mapping the reaction coordinates of enzymatic defluorination. J Am Chem Soc 2011; 133:7461-8. [PMID: 21510690 DOI: 10.1021/ja200277d] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The carbon-fluorine bond is the strongest covalent bond in organic chemistry, yet fluoroacetate dehalogenases can readily hydrolyze this bond under mild physiological conditions. Elucidating the molecular basis of this rare biocatalytic activity will provide the fundamental chemical insights into how this formidable feat is achieved. Here, we present a series of high-resolution (1.15-1.80 Å) crystal structures of a fluoroacetate dehalogenase, capturing snapshots along the defluorination reaction: the free enzyme, enzyme-fluoroacetate Michaelis complex, glycolyl-enzyme covalent intermediate, and enzyme-product complex. We demonstrate that enzymatic defluorination requires a halide pocket that not only supplies three hydrogen bonds to stabilize the fluoride ion but also is finely tailored for the smaller fluorine halogen atom to establish selectivity toward fluorinated substrates. We have further uncovered dynamics near the active site which may play pivotal roles in enzymatic defluorination. These findings may ultimately lead to the development of novel defluorinases that will enable the biotransformation of more complex fluorinated organic compounds, which in turn will assist the synthesis, detoxification, biodegradation, disposal, recycling, and regulatory strategies for the growing markets of organofluorines across major industrial sectors.
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Affiliation(s)
- Peter W Y Chan
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Lin C, Yang L, Xu G, Wu J. Biodegradation and metabolic pathway of β-chlorinated aliphatic acid in Bacillus sp. CGMCC no. 4196. Appl Microbiol Biotechnol 2011; 90:689-96. [PMID: 21210101 DOI: 10.1007/s00253-010-3081-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2010] [Revised: 12/17/2010] [Accepted: 12/19/2010] [Indexed: 10/18/2022]
Abstract
In this study, a bacterial Bacillus sp. CGMCC no. 4196 was isolated from mud. This strain exhibited the ability to degrade high concentration of 3-chloropropionate (3-CPA, 120 mM) or 3-chlorobutyrate (30 mM), but not chloroacetate or 2-chloropropionate (2-CPA). The growing cells, resting cells, and cell-free extracts from this bacterium had the capability of 3-CPA degradation. The results indicated that the optimum biocatalyst for 3-CPA biodegradation was the resting cells. The 3-CPA biodegradation pathway was further studied through the metabolites and critical enzymes analysis by HPLC, LC-MS, and colorimetric method. The results demonstrated that the metabolites of 3-CPA were 3-hydroxypropionic acid (3-HP) and malonic acid semialdehyde, and the critical enzymes were 3-CPA dehalogenase and 3-HP dehydroxygenase. Thus, the mechanism of the dehalogenase-catalyzed reaction was inferred as hydrolytic dehalogenation which was coenzyme A-independent and oxygen-independent. Finally, the pathway of β-chlorinated aliphatic acid biodegradation could be concluded as follows: the β-chlorinated acid is first hydrolytically dehalogenated to the β-hydroxyl aliphatic acid, and the hydroxyl aliphatic acid is oxidized to β-carbonyl aliphatic acid by β-hydroxy aliphatic acid dehydroxygenase. It is the first report that 3-HP was produced from 3-CPA by β-chlorinated aliphatic acid dehalogenase.
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Affiliation(s)
- Chunjiao Lin
- Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
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Seffernick JL, Reynolds E, Fedorov AA, Fedorov E, Almo SC, Sadowsky MJ, Wackett LP. X-ray structure and mutational analysis of the atrazine Chlorohydrolase TrzN. J Biol Chem 2010; 285:30606-14. [PMID: 20659898 DOI: 10.1074/jbc.m110.138677] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Atrazine chlorohydrolase, TrzN (triazine hydrolase or atrazine chlorohydrolase 2), initiates bacterial metabolism of the herbicide atrazine by hydrolytic displacement of a chlorine substituent from the s-triazine ring. The present study describes crystal structures and reactivity of wild-type and active site mutant TrzN enzymes. The homodimer native enzyme structure, solved to 1.40 Å resolution, is a (βα)(8) barrel, characteristic of members of the amidohydrolase superfamily. TrzN uniquely positions threonine 325 in place of a conserved aspartate that ligates the metal in most mononuclear amidohydrolases superfamily members. The threonine side chain oxygen atom is 3.3 Å from the zinc atom and 2.6 Å from the oxygen atom of zinc-coordinated water. Mutation of the threonine to a serine resulted in a 12-fold decrease in k(cat)/K(m), largely due to k(cat), whereas the T325D and T325E mutants had immeasurable activity. The structure and kinetics of TrzN are reminiscent of carbonic anhydrase, which uses a threonine to assist in positioning water for reaction with carbon dioxide. An isosteric substitution in the active site glutamate, E241Q, showed a large diminution in activity with ametryn, no detectable activity with atratone, and a 10-fold decrease with atrazine, when compared with wild-type TrzN. Activity with the E241Q mutant was nearly constant from pH 6.0 to 10.0, consistent with the loss of a proton-donating group. Structures for TrzN-E241Q were solved with bound ametryn and atratone to 1.93 and 1.64 Å resolution, respectively. Both structure and kinetic determinations suggest that the Glu(241) side chain provides a proton to N-1 of the s-triazine substrate to facilitate nucleophilic displacement at the adjacent C-2.
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Ruthenacycles and Iridacycles as Catalysts for Asymmetric Transfer Hydrogenation and Racemisation. Top Catal 2010. [DOI: 10.1007/s11244-010-9569-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Wang G, Li R, Li S, Jiang J. A novel hydrolytic dehalogenase for the chlorinated aromatic compound chlorothalonil. J Bacteriol 2010; 192:2737-45. [PMID: 20363940 PMCID: PMC2876492 DOI: 10.1128/jb.01547-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Accepted: 03/25/2010] [Indexed: 11/20/2022] Open
Abstract
Dehalogenases play key roles in the detoxification of halogenated aromatics. Interestingly, only one hydrolytic dehalogenase for halogenated aromatics, 4-chlorobenzoyl-coenzyme A (CoA) dehalogenase, has been reported. Here, we characterize another novel hydrolytic dehalogenase for a halogenated aromatic compound from the 2,4,5,6-tetrachloroisophthalonitrile (chlorothalonil)-degrading strain of Pseudomonas sp. CTN-3, which we have named Chd. Chd catalyzes a hydroxyl substitution at the 4-chlorine atom of chlorothalonil. The metabolite of the Chd dehalogenation, 4-hydroxy-trichloroisophthalonitrile, was identified by reverse-phase high-performance liquid chromatography (HPLC), tandem mass spectrometry (MS/MS), and nuclear magnetic resonance (NMR). Chd dehalogenates chlorothalonil under anaerobic and aerobic conditions and does not require the presence of cofactors such as CoA and ATP. Chd contains a putative conserved domain of the metallo-beta-lactamase superfamily and shows the highest identity with several metallohydrolases (24 to 29%). Chd is a monomer (36 kDa), and the isoelectric point (pI) of Chd is estimated to be 4.13. Chd has a dissociation constant (K(m)) of 0.112 mM and an overall catalytic rate (k(cat)) of 207 s(-1) for chlorothalonil. Chd is completely inhibited by 1,10-phenanthroline, diethyl pyrocarbonate, and N-bromosuccinic acid. Site-directed mutagenesis of Chd revealed that histidines 128 and 157, serine 126, aspartates 45, 130 and 184, and tryptophan 241 were essential for the dehalogenase activity. Chd differs from other reported hydrolytic dehalogenases based on the analysis of amino acid sequences and catalytic mechanisms. This study provides an excellent dehalogenase candidate for mechanistic study of hydrolytic dehalogenation of halogenated aromatic compound.
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Affiliation(s)
- Guangli Wang
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, Jiangsu Province, People's Republic of China
| | - Rong Li
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, Jiangsu Province, People's Republic of China
| | - Shunpeng Li
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, Jiangsu Province, People's Republic of China
| | - Jiandong Jiang
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, Jiangsu Province, People's Republic of China
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Domínguez de María P, van Gemert RW, Straathof AJJ, Hanefeld U. Biosynthesis of ethers: unusual or common natural events? Nat Prod Rep 2010; 27:370-92. [PMID: 20179877 DOI: 10.1039/b809416k] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ether bonds are found in a wide variety of natural products--mainly secondary metabolites--including lipids, oxiranes, terpenoids, flavonoids, polyketides, and carbohydrate derivatives, to name some representative examples. To furnish such a biodiversity of structures, a large number of different enzymes are involved in several different biosynthetic pathways. Depending on the compound and on the (micro) environment in which the reaction is performed, ethers are produced by very different (enzymatic) reactions, thus providing an impressive display of how Nature has combined evolution and thermodynamics to be able to produce a vast number of compounds. In addition, many of these compounds possess different biological activities of pharmacological interest. Moreover, some of these ethers (i.e., epoxides) have high chemical reactivity, and can be useful starting materials for further synthetic processes. This review aims to provide an overview of the different strategies that are found in Nature for the formation of these "bioethers". Both fundamental and practical insights of the biosynthetic processes will be discussed.
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Nakamura T, Yamaguchi A, Kondo H, Watanabe H, Kurihara T, Esaki N, Hirono S, Tanaka S. Roles of K151 and D180 in L-2-haloacid dehalogenase fromPseudomonassp. YL: Analysis by molecular dynamics andab initiofragment molecular orbital calculations. J Comput Chem 2009; 30:2625-34. [DOI: 10.1002/jcc.21273] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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McTamney PM, Rokita SE. A mammalian reductive deiodinase has broad power to dehalogenate chlorinated and brominated substrates. J Am Chem Soc 2009; 131:14212-3. [PMID: 19777994 DOI: 10.1021/ja906642n] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iodotyrosine deiodinase is essential for iodide homeostasis and proper thyroid function in mammals. This enzyme promotes a net reductive deiodination of 3-iodotyrosine to form iodide and tyrosine. Such a reductive dehalogenation is uncommon in aerobic organisms, and its requirement for flavin mononucleotide is even more uncommon in catalysis. Reducing equivalents are now shown to transfer directly from the flavin to the halogenated substrate without involvement of other components typically included in the standard enzymatic assay. Additionally, the deiodinase has been discovered to act as a debrominase and a dechlorinase. These new activities expand the possible roles of flavin in biological catalysis and provide a foundation for determining the mechanism of this unusual process.
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Affiliation(s)
- Patrick M McTamney
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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Chan WY, Wong M, Guthrie J, Savchenko AV, Yakunin AF, Pai EF, Edwards EA. Sequence- and activity-based screening of microbial genomes for novel dehalogenases. Microb Biotechnol 2009; 3:107-20. [PMID: 21255311 PMCID: PMC3815952 DOI: 10.1111/j.1751-7915.2009.00155.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Dehalogenases are environmentally important enzymes that detoxify organohalogens by cleaving their carbon‐halogen bonds. Many microbial genomes harbour enzyme families containing dehalogenases, but a sequence‐based identification of genuine dehalogenases with high confidence is challenging because of the low sequence conservation among these enzymes. Furthermore, these protein families harbour a rich diversity of other enzymes including esterases and phosphatases. Reliable sequence determinants are necessary to harness genome sequencing‐efforts for accelerating the discovery of novel dehalogenases with improved or modified activities. In an attempt to extract dehalogenase sequence fingerprints, 103 uncharacterized potential dehalogenase candidates belonging to the α/β hydrolase (ABH) and haloacid dehalogenase‐like hydrolase (HAD) superfamilies were screened for dehalogenase, esterase and phosphatase activity. In this first biochemical screen, 1 haloalkane dehalogenase, 1 fluoroacetate dehalogenase and 5 l‐2‐haloacid dehalogenases were found (success rate 7%), as well as 19 esterases and 31 phosphatases. Using this functional data, we refined the sequence‐based dehalogenase selection criteria and applied them to a second functional screen, which identified novel dehalogenase activity in 13 out of only 24 proteins (54%), increasing the success rate eightfold. Four new l‐2‐haloacid dehalogenases from the HAD superfamily were found to hydrolyse fluoroacetate, an activity never previously ascribed to enzymes in this superfamily.
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Affiliation(s)
- Wing Yiu Chan
- Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
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Deng H, O'Hagan D. The fluorinase, the chlorinase and the duf-62 enzymes. Curr Opin Chem Biol 2009; 12:582-92. [PMID: 18675376 DOI: 10.1016/j.cbpa.2008.06.036] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 06/27/2008] [Accepted: 06/30/2008] [Indexed: 10/21/2022]
Abstract
The fluorinase from Streptomyces cattleya and chlorinase from Salinispora tropica have a commonality in that they mediate nucleophilic reactions of their respective halide ions to the C-5' carbon of S-adenosyl-L-methionine (SAM). These enzyme reactions fall into the relatively small group of S(N)2 substitution reactions found in enzymology. These enzymes have some homology to a larger class of proteins expressed by the duf-62 gene, of which around 200 representatives have been sequenced and deposited in databases. The duf-62 genes express a protein which mediates a hydrolytic cleavage of SAM to generate adenosine and L-methionine. Superficially this enzyme operates very similarly to the halogenases in that water/hydroxide replaces the halide ion. However structural examination of the duf-62 gene product reveals a very different organisation of the active site suggesting a novel mechanism for water activation.
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Affiliation(s)
- Hai Deng
- University of St Andrews, School of Chemistry and Centre for Biomolecular Sciences, North Haugh, St Andrews, Fife KY16 9ST, UK.
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Abstract
Simple halogen substituents frequently afford key structural features that account for the potency and selectivity of natural products, including antibiotics and hormones. For example, when a single chlorine atom on the antibiotic vancomycin is replaced by hydrogen, the resulting antibacterial activity decreases by up to 70% (HarrisC. M.; KannanR.; KopeckaH.; HarrisT. M.J. Am. Chem. Soc.1985, 107, 6652−6658). This Account analyzes how structure underlies mechanism in halogenases, the molecular machines designed by nature to incorporate halogens into diverse substrates.
Traditional synthetic methods of integrating halogens into complex molecules are often complicated by a lack of specificity and regioselectivity. Nature, however, has developed a variety of elegant mechanisms for halogenating specific substrates with both regio- and stereoselectivity. An improved understanding of the biological routes toward halogenation could lead to the development of novel synthetic methods for the creation of new compounds with enhanced functions. Already, researchers have co-opted a fluorinase from the microorganism Streptomyces cattleya to produce 18F-labeled molecules for use in positron emission tomography (PET) (DengH.; CobbS. L.; GeeA. D.; LockhartA.; MartarelloL.; McGlincheyR. P.; O’HaganD.; OnegaM.Chem. Commun.2006, 652−654). Therefore, the discovery and characterization of naturally occurring enzymatic halogenation mechanisms has become an active area of research. The catalogue of known halogenating enzymes has expanded from the familiar haloperoxidases to include oxygen-dependent enzymes and fluorinases. Recently, the discovery of a nucleophilic halogenase that catalyzes chlorinations has expanded the repertoire of biological halogenation chemistry (DongC.; HuangF.; DengH.; SchaffrathC.; SpencerJ. B.; O’HaganD.; NaismithJ. H.Nature2004, 427, 561−56514765200). Structural characterization has provided a basis toward a mechanistic understanding of the specificity and chemistry of these enzymes. In particular, the latest crystallographic snapshots of active site architecture and halide binding sites have provided key insights into enzyme catalysis. Herein is a summary of the five classes of halogenases, focusing on the three most recently discovered: flavin-dependent halogenases, non-heme iron-dependent halogenases, and nucleophilic halogenases. Further, the potential roles of halide-binding sites in determining halide selectivity are discussed, as well as whether or not binding-site composition is always a seminal factor for selectivity. Expanding our understanding of the basic chemical principles that dictate the activity of the halogenases will advance both biology and chemistry. A thorough mechanistic analysis will elucidate the biological principles that dictate specificity, and the application of those principles to new synthetic techniques will expand the utility of halogenations in small-molecule development.
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