101
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Hölscher T, Krajmalnik-Brown R, Ritalahti KM, Von Wintzingerode F, Görisch H, Löffler FE, Adrian L. Multiple nonidentical reductive-dehalogenase-homologous genes are common in Dehalococcoides. Appl Environ Microbiol 2004; 70:5290-7. [PMID: 15345412 PMCID: PMC520921 DOI: 10.1128/aem.70.9.5290-5297.2004] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Degenerate primers were used to amplify large fragments of reductive-dehalogenase-homologous (RDH) genes from genomic DNA of two Dehalococcoides populations, the chlorobenzene- and dioxin-dechlorinating strain CBDB1 and the trichloroethene-dechlorinating strain FL2. The amplicons (1,350 to 1,495 bp) corresponded to nearly complete open reading frames of known reductive dehalogenase genes and short fragments (approximately 90 bp) of genes encoding putative membrane-anchoring proteins. Cloning and restriction analysis revealed the presence of at least 14 different RDH genes in each strain. All amplified RDH genes showed sequence similarity with known reductive dehalogenase genes over the whole length of the sequence and shared all characteristics described for reductive dehalogenases. Deduced amino acid sequences of seven RDH genes from strain CBDB1 were 98.5 to 100% identical to seven different RDH genes from strain FL2, suggesting that both strains have an overlapping substrate range. All RDH genes identified in strains CBDB1 and FL2 were related to the RDH genes present in the genomes of Dehalococcoides ethenogenes strain 195 and Dehalococcoides sp. strain BAV1; however, sequence identity did not exceed 94.4 and 93.1%, respectively. The presence of RDH genes in strains CBDB1, FL2, and BAV1 that have no orthologs in strain 195 suggests that these strains possess dechlorination activities not present in strain 195. Comparative sequence analysis identified consensus sequences for cobalamin binding in deduced amino acid sequences of seven RDH genes. In conclusion, this study demonstrates that the presence of multiple nonidentical RDH genes is characteristic of Dehalococcoides strains.
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Affiliation(s)
- Tina Hölscher
- School of Civil and Environmental Engineering, 311 Ferst Dr., 3228 ES and T Building, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA
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102
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Thibodeau J, Gauthier A, Duguay M, Villemur R, Lépine F, Juteau P, Beaudet R. Purification, cloning, and sequencing of a 3,5-dichlorophenol reductive dehalogenase from Desulfitobacterium frappieri PCP-1. Appl Environ Microbiol 2004; 70:4532-7. [PMID: 15294782 PMCID: PMC492329 DOI: 10.1128/aem.70.8.4532-4537.2004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A membrane-associated 3,5-dichlorophenol reductive dehalogenase was isolated from Desulfitobacterium frappieri PCP-1. The highest dehalogenase activity was observed with the biomass cultured at 22 degrees C, compared to 30 and 37 degrees C, where the cell suspensions were 2.2 and 9.6 times less active, respectively. The reductive dehalogenase was purified 12.7-fold to apparent homogeneity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single band with an apparent molecular mass of 57 kDa. Its dechlorinating activity was not inhibited by sulfate and nitrate but was completely inhibited by 2.5 mM sulfite and 10 mM KCN. A mixture of iodopropane and titanium citrate caused a light-reversible inhibition of the dechlorinating activities, suggesting the involvement of a corrinoid cofactor. Several polychlorophenols were dechlorinated at the meta and para positions. The apparent K(m) for 3,5-dicholorophenol was 49.3 +/- 3.1 microM at a methyl viologen concentration of 2 mM. Six internal tryptic peptides were sequenced by mass spectrometry. One open reading frame (ORF) was found in the Desulfitobacterium hafniense genome containing these peptide sequences. This ORF corresponds to a gene coding for a CprA-type reductive dehalogenase. The corresponding ORF (named cprA5) in D. frappieri PCP-1 was cloned and sequenced. The cprA5 gene codes for a 548-amino-acid protein that contains a twin-arginine-type signal for secretion. The gene product has a cobalamin binding site motif and two iron-sulfur binding motifs and shows 66% identity (76 to 77% similarity) with some tetrachloroethene reductive dehalogenases. This is the first CprA-type reductive dehalogenase that can dechlorinate chlorophenols at the meta and para positions.
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Affiliation(s)
- Jacinthe Thibodeau
- Institut National de la Recherche Scientifique, INRS-Institut Armand-Frappier, Université du Québec, 531 boul. des Prairies, Laval, QC H7V 1B7, Canada
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103
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Müller JA, Rosner BM, Von Abendroth G, Meshulam-Simon G, McCarty PL, Spormann AM. Molecular identification of the catabolic vinyl chloride reductase from Dehalococcoides sp. strain VS and its environmental distribution. Appl Environ Microbiol 2004; 70:4880-8. [PMID: 15294827 PMCID: PMC492378 DOI: 10.1128/aem.70.8.4880-4888.2004] [Citation(s) in RCA: 235] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Reductive dehalogenation of vinyl chloride (VC) to ethene is the key step in complete anaerobic degradation of chlorinated ethenes. VC-reductive dehalogenase was partially purified from a highly enriched culture of the VC-respiring Dehalococcoides sp. strain VS. The enzyme reduced VC and all dichloroethene (DCE) isomers, but not tetrachloroethene (PCE) or trichloroethene (TCE), at high rates. By using reversed genetics, the corresponding gene (vcrA) was isolated and characterized. Based on the predicted amino acid sequence, VC reductase is a novel member of the family of corrinoid/iron-sulfur cluster containing reductive dehalogenases. The vcrA gene was found to be cotranscribed with vcrB, encoding a small hydrophobic protein presumably acting as membrane anchor for VC reductase, and vcrC, encoding a protein with similarity to transcriptional regulators of the NosR/NirI family. The vcrAB genes were subsequently found to be present and expressed in other cultures containing VC-respiring Dehalococcoides organisms and could be detected in water samples from a field site contaminated with chlorinated ethenes. Therefore, the vcrA gene identified here may be a useful molecular target for evaluating, predicting, and monitoring in situ reductive VC dehalogenation.
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Affiliation(s)
- Jochen A Müller
- Department of Civil and Environmental Engineering, Clark Center East Wing, E250A, Stanford University, Stanford, CA 94305-5429, USA
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104
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Griffin BM, Tiedje JM, Löffler FE. Anaerobic microbial reductive dechlorination of tetrachloroethene to predominately trans-1,2-dichloroethene. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2004; 38:4300-4303. [PMID: 15382856 DOI: 10.1021/es035439g] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
While most sites and all characterized PCE and TCE dechlorinating anaerobic bacteria produce cis-DCE as the major DCE isomer, significant amounts of trans-DCE are found in the environment. We have obtained microcosms from some sites and enrichment cultures that produce more trans-DCE than cis-DCE. These cultures reductively dechlorinated PCE and TCE to trans-DCE and cis-DCE simultaneously and in a ratio of 3(+/-0.5):1 that was stable through serial transfers with a variety of electron donors and occurred in both methanogenic and nonmethanogenic enrichments. Two sediment-free, nonmethanogenic enrichment cultures produced trans-DCE at rates of up to 2.5 micromol L(-1) day(-1). Dehalococcoides populations were detected in both trans-DCE producing cultures by their 16S rRNA gene sequences, and trans-DCE was produced in the presence of ampicillin. Because trans-DCE can be the major product from PCE and TCE microbial dechlorination, high fractions of trans-DCE at chloroethene-contaminated sites are not necessarily from source contamination.
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Affiliation(s)
- Benjamin M Griffin
- Center for Microbial Ecology, Department of Microbiology and Molecular Genetics, and Institute for Environmental Toxicology, Michigan State University, East Lansing, Michigan 48824-1325, USA
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105
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Schmitz RP, Diekert G. The fdh operon of Sulfurospirillum multivorans. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09701.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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106
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Ruppe S, Neumann A, Diekert G, Vetter W. Abiotic transformation of toxaphene by superreduced vitamin B12 and dicyanocobinamide. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2004; 38:3063-3067. [PMID: 15224736 DOI: 10.1021/es034994f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Toxaphene is a complex organochlorine pesticide mixture, residues of which are widespread in the environment. Previous studies with the isolated bacterium Sulfurospirillum (formerly Dehalospirillum) multivorans resulted in an effective anaerobic biotransformation of toxaphene. Since the bacterium contains a corrinoid derivative in the active center of the tetrachloroethene dehalogenase, we attempted to use superreduced corrinoids for abiotic transformation of toxaphene. The two corrinoids studied were dicyanocobinamide and cyanocobalamin (vitamin B12). Superreduced dicyanocobinamide mediated a rapid transformation of toxaphene. More than 90% of the initial pool was transformed within 6 h. The transformation was nonselective, and even the most persistent metabolite in environmental samples, the so-called dead-end metabolite 2-exo,3-endo,6-exo,8,9,10-hexachlorobornane (B6-923 or Hx-Sed) was transformed within hours. Superreduced cyanocobalamin was also able to transform toxaphene albeit at significantly lower velocity. The lack of transformation products detectable in gas chromatograms of hexanes-extracted fractions of the assays suggests rapid, sequential dehalogenation and/or destruction of the C10-hydrocarbon backbone of the compounds of technical toxaphene.
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Affiliation(s)
- Steffen Ruppe
- Department of Food Chemistry, Friedrich-Schiller-University of Jena, Dornburger Strasse 25, Jena, Germany
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107
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Griebler C, Adrian L, Meckenstock R, Richnow H. Stable carbon isotope fractionation during aerobic and anaerobic transformation of trichlorobenzene. FEMS Microbiol Ecol 2004; 48:313-21. [DOI: 10.1016/j.femsec.2004.02.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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108
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109
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Costentin C, Robert M, Savéant JM. Successive removal of chloride ions from organic polychloride pollutants. Mechanisms of reductive electrochemical elimination in aliphatic gem-polychlorides, alpha,beta-polychloroalkenes, and alpha,beta-polychloroalkanes in mildly protic medium. J Am Chem Soc 2003; 125:10729-39. [PMID: 12940759 DOI: 10.1021/ja036141t] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The factors that control the successive reductive expulsion of chloride ions from aliphatic gem-polychlorides are investigated, taking as examples the electrochemical reduction of polychloromethanes and polychloroacetonitriles in N,N-dimethylformamide. At each elimination stage, the reaction involves, as a rate-determining step, the transfer of one electron concerted with the cleavage of the carbon-chloride bond. The second step is an immediate electron transfer to the ensuing radical, taking place at a potential more positive than the potential at which the first electron transfer occurs. The carbanion thus formed is sufficiently basic to be protonated by any trace weak acid present in the reaction medium. The three successive elimination steps require increasingly negative potentials. Application of the "sticky" dissociative electron transfer model allows one to quantitatively unravel the factors that control the energetics of the successive reductive expulsion of chloride ions. The large potential gaps between each stage stem primarily from large differences in the dissociative standard potentials. They are also strongly affected by two cumulative intrinsic activation barrier factors, namely, the bond dissociation energy of the substrate that decreases with the number of chlorine atoms and the interaction between chloride ion and the radical that increases in the same direction. In the case of alpha,beta-polychloroethanes (Cl(3)C-CCl(3), Cl(2)HC-CCl(3), Cl(2)HC-CHCl(2), ClH(2)C-CHCl(2)) too, the first step is a dissociative electron transfer with sizable ion-radical interactions in the product cluster. Likewise, a second electron transfer immediately leads to the carbanion, which however prefers to expel a second chloride ion, leading to the corresponding olefin, than to be protonated to the hydrogenolysis product. The ion-radical interaction in the product cluster plays a major role in the control of the reduction potential. The reduction of the alpha,beta-polychloroethenes (Cl(2)C=CCl(2), ClHC=CCl(2), ClHC=CHCl) follows a similar 2e(-)-2Cl(-) reaction sequence, leading then to the corresponding alkynes. However, unlike the polychloroethane case, the expulsion of the first chloride ion follows a stepwise electron transfer/bond cleavage mechanism. The reduction potential is thus essentially governed by the thermodynamics of the anion radical formation.
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Affiliation(s)
- Cyrille Costentin
- Laboratoire d'Electrochimie Moléculaire, Université de Paris 7-Denis Diderot, Case Courrier 7107, 2 place Jussieu, 75251 Paris Cedex 05, France
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110
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Maillard J, Schumacher W, Vazquez F, Regeard C, Hagen WR, Holliger C. Characterization of the corrinoid iron-sulfur protein tetrachloroethene reductive dehalogenase of Dehalobacter restrictus. Appl Environ Microbiol 2003; 69:4628-38. [PMID: 12902251 PMCID: PMC169082 DOI: 10.1128/aem.69.8.4628-4638.2003] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2003] [Accepted: 05/07/2003] [Indexed: 11/20/2022] Open
Abstract
The membrane-bound tetrachloroethene reductive dehalogenase (PCE-RDase) (PceA; EC 1.97.1.8), the terminal component of the respiratory chain of Dehalobacter restrictus, was purified 25-fold to apparent electrophoretic homogeneity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single band with an apparent molecular mass of 60 +/- 1 kDa, whereas the native molecular mass was 71 +/- 8 kDa according to size exclusion chromatography in the presence of the detergent octyl-beta-D-glucopyranoside. The monomeric enzyme contained (per mol of the 60-kDa subunit) 1.0 +/- 0.1 mol of cobalamin, 0.6 +/- 0.02 mol of cobalt, 7.1 +/- 0.6 mol of iron, and 5.8 +/- 0.5 mol of acid-labile sulfur. Purified PceA catalyzed the reductive dechlorination of tetrachloroethene and trichloroethene to cis-1,2-dichloroethene with a specific activity of 250 +/- 12 nkat/mg of protein. In addition, several chloroethanes and tetrachloromethane caused methyl viologen oxidation in the presence of PceA. The K(m) values for tetrachloroethene, trichloroethene, and methyl viologen were 20.4 +/- 3.2, 23.7 +/- 5.2, and 47 +/- 10 micro M, respectively. The PceA exhibited the highest activity at pH 8.1 and was oxygen sensitive, with a half-life of activity of 280 min upon exposure to air. Based on the almost identical N-terminal amino acid sequences of PceA of Dehalobacter restrictus, Desulfitobacterium hafniense strain TCE1 (formerly Desulfitobacterium frappieri strain TCE1), and Desulfitobacterium hafniense strain PCE-S (formerly Desulfitobacterium frappieri strain PCE-S), the pceA genes of the first two organisms were cloned and sequenced. Together with the pceA genes of Desulfitobacterium hafniense strains PCE-S and Y51, the pceA genes of Desulfitobacterium hafniense strain TCE1 and Dehalobacter restrictus form a coherent group of reductive dehalogenases with almost 100% sequence identity. Also, the pceB genes, which may code for a membrane anchor protein of PceA, and the intergenic regions of Dehalobacter restrictus and the three desulfitobacteria had identical sequences. Whereas the cprB (chlorophenol reductive dehalogenase) genes of chlorophenol-dehalorespiring bacteria are always located upstream of cprA, all pceB genes known so far are located downstream of pceA. The possible consequences of this feature for the annotation of putative reductive dehalogenase genes are discussed, as are the sequence around the iron-sulfur cluster binding motifs and the type of iron-sulfur clusters of the reductive dehalogenases of Dehalobacter restrictus and Desulfitobacterium dehalogenans identified by electron paramagnetic resonance spectroscopy.
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Affiliation(s)
- Julien Maillard
- ENAC-Laboratory for Environmental Biotechnology, Swiss Federal Institute of Technology (EPFL) CH-1015 Lausanne, The Netherlands
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111
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Boyer A, Pagé-BéLanger R, Saucier M, Villemur R, Lépine F, Juteau P, Beaudet R. Purification, cloning and sequencing of an enzyme mediating the reductive dechlorination of 2,4,6-trichlorophenol from Desulfitobacterium frappieri PCP-1. Biochem J 2003; 373:297-303. [PMID: 12697029 PMCID: PMC1223485 DOI: 10.1042/bj20021837] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2002] [Revised: 04/03/2003] [Accepted: 04/16/2003] [Indexed: 11/17/2022]
Abstract
A new membrane-associated 2,4,6-trichlorophenol reductive dehalogenase from Desulfitobacterium frappieri PCP-1 was isolated. Initial characterization of the crude preparation showed that the dechlorinating activity was sensitive to oxygen, and its optimum pH was 7.0. Its dechlorinating activity was not inhibited by sulphate, was completely inhibited by 1 mM sulphite, and partially inhibited by 5 mM sodium azide and by more than 5 mM nitrate. Several polychlorophenols were dechlorinated in the ortho position with respect to the hydroxy group. A dehalogenase was purified to apparent homogeneity. SDS gel electrophoresis revealed a single protein band with a molecular mass of 37 kDa. However, after two-dimensional gel electrophoresis, this band was composed of three isoforms. MS analyses showed that the three isoforms were from the same protein and the molecular mass of the most abundant isoform is 33800 Da. A mixture of iodopropane and titanium citrate caused a light-reversible inhibition of the dechlorinating activity, suggesting the involvement of a corrinoid cofactor. The apparent K(m) value for 2,4,6-trichlorophenol and pentachlorophenol were 18.3+/-2.8 microM and 26.8+/-2.9 microM respectively, at a methyl viologen concentration of 2 mM. The N-terminal amino acid sequence and an internal tryptic peptide sequence were determined. One open reading frame (ORF) was found in the Desulfitobacterium hafniense genome containing these peptides sequences. The corresponding ORF in D. frappieri PCP-1 was cloned and sequenced. This ORF, that we designated crdA, showed no homology with any known dehalogenase, suggesting a distinct reductive dehalogenase.
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Affiliation(s)
- Annie Boyer
- INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada, H7V 1B7
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112
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Abstract
Vitamin B12 is a complex organometallic cofactor associated with three subfamilies of enzymes: the adenosylcobalamin-dependent isomerases, the methylcobalamin-dependent methyltransferases, and the dehalogenases. Different chemical aspects of the cofactor are exploited during catalysis by the isomerases and the methyltransferases. Thus, the cobalt-carbon bond ruptures homolytically in the isomerases, whereas it is cleaved heterolytically in the methyltransferases. The reaction mechanism of the dehalogenases, the most recently discovered class of B12 enzymes, is poorly understood. Over the past decade our understanding of the reaction mechanisms of B12 enzymes has been greatly enhanced by the availability of large amounts of enzyme that have afforded detailed structure-function studies, and these recent advances are the subject of this review.
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Affiliation(s)
- Ruma Banerjee
- Department of Biochemistry, University of Nebraska, Lincoln, Nebraska 68588-0664, USA. ;
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113
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Hölscher T, Görisch H, Adrian L. Reductive dehalogenation of chlorobenzene congeners in cell extracts of Dehalococcoides sp. strain CBDB1. Appl Environ Microbiol 2003; 69:2999-3001. [PMID: 12732577 PMCID: PMC154522 DOI: 10.1128/aem.69.5.2999-3001.2003] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enzymatic reductive dehalogenation of tri-, tetra-, penta-, and hexachlorobenzenes was demonstrated in cell extracts with low protein concentration (0.5 to 1 micro g of protein/ml) derived from the chlorobenzene-respiring anaerobe Dehalococcoides sp. strain CBDB1. 1,2,3-trichlorobenzene dehalogenase activity was associated with the membrane fraction. Light-reversible inhibition by alkyl iodides indicated the presence of a corrinoid cofactor.
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Affiliation(s)
- Tina Hölscher
- Fachgebiet Technische Biochemie, Institut für Biotechnologie, Technische Universität Berlin, Seestrasse 13, D-13353 Berlin, Germany.
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114
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Nonnenberg C, van der Donk WA, Zipse H. Reductive Dechlorination of Trichloroethylene: A Computational Study. J Phys Chem A 2002. [DOI: 10.1021/jp0264073] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christel Nonnenberg
- Department Chemie, LMU München, Butenandtstrasse 13, D-81377 München, Germany, and Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801
| | - Wilfred A. van der Donk
- Department Chemie, LMU München, Butenandtstrasse 13, D-81377 München, Germany, and Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801
| | - Hendrik Zipse
- Department Chemie, LMU München, Butenandtstrasse 13, D-81377 München, Germany, and Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801
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115
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Villemur R, Saucier M, Gauthier A, Beaudet R. Occurrence of several genes encoding putative reductive dehalogenases in Desulfitobacterium hafniense/frappieri and Dehalococcoides ethenogenes. Can J Microbiol 2002; 48:697-706. [PMID: 12381026 DOI: 10.1139/w02-057] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Desulfitobacterium frappieri PCP-1 has the capacity to dehalogenate several halogenated aromatic compounds by reductive dehalogenation, however, the genes encoding the enzymes involved in such processes have not yet been identified. Using a degenerate oligonucleotide corresponding to a conserved sequence of CprA/PceA reductive dehalogenases, a cprA-like gene fragment was amplified by PCR from this bacterial strain. A Desulfitobacterium frappieri PCP-1 cosmid library was screened with the PCR product, allowing the cloning and sequencing of a 1.9-kb fragment. This fragment contains a nucleic acid sequence identical to one genomic contig of Desulfitobacterium hafniense, a bacterium closely related to Desulfitobacterium frappieri that is also involved in reductive dehalogenation. Other genes related to the Desulfitobacterium dehalogenans cpr locus were identified in this contig. Interestingly, the gene arrangement shows the presence of two copies of cprA-, cprB-, cprC-, cprD-, cprK-, and cprT-related genes, suggesting that gene duplication occurred within this chromosomic region. The screening of Delfitobacterium hafniense genomic contigs with a CprA-deduced amino acid sequence revealed two other cprA-like genes. Microbial genomes available in gene databases were also analyzed for sequences related to CprA/PceA. Two open reading frames encoding other putative reductive dehalogenases in Desulfitobacterium hafniense contigs were detected, along with 17 in the Dehalococcoides ethenogenes genome, a bacterium involved in the reductive dehalogenation of tetrachloroethene to ethene. The fact that several gene encoding putative reductive dehalogenases exist in Delfitobacterium hafniense, probably in other members of the genus Desulfitobacterium, and in Dehalococcoides ethenogenes suggests that these bacteria use distinct but related enzymes to achieve the dehalogenation of several chlorinated compounds [corrected].
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Affiliation(s)
- Richard Villemur
- Institut national de la recherche scientifique, Institut Armand-Frappier, Laval, QC, Canada.
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116
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Suyama A, Yamashita M, Yoshino S, Furukawa K. Molecular characterization of the PceA reductive dehalogenase of desulfitobacterium sp. strain Y51. J Bacteriol 2002; 184:3419-25. [PMID: 12057934 PMCID: PMC135124 DOI: 10.1128/jb.184.13.3419-3425.2002] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The tetrachloroethene (PCE) reductive dehalogenase (encoded by the pceA gene and designated PceA dehalogenase) of Desulfitobacterium sp. strain Y51 was purified and characterized. The expression of the enzyme was highly induced in the presence of PCE and trichloroethene (TCE). The purified enzyme catalyzed the reductive dehalogenation of PCE via TCE to cis-1,2-dichloroethene at a specific activity of 113.6 nmol x min(-1) x mg of protein(-1). The apparent K(m) values for PCE and TCE were 105.7 and 535.3 microM, respectively. Chlorinated ethenes other than PCE and TCE were not dehalogenated. However, the enzyme exhibited dehalogenation activity for various chlorinated ethanes such as hexachloroethane, pentachloroethane, 1,1,1,2-tetrachloroethane, and 1,1,2,2-tetrachloroethane. The pceA gene of Desulfitobacterium sp. strain Y51 was identified in a 2.8-kb DNA fragment and used to express the protein in Escherichia coli for the preparation of antibodies. Immunoblot analyses located PceA in the periplasm of the cell.
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Affiliation(s)
- Akiko Suyama
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581. Towakagaku Co., Ltd., Hiroshima 730-0841, Japan
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117
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Hohnstock-Ashe AM, Plummer SM, Yager RM, Baveye P, Madsen EL. Further biogeochemical characterization of a trichloroethene-contaminated fractured dolomite aquifer: electron source and microbial communities involved in reductive dechlorination. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2001; 35:4449-56. [PMID: 11757600 DOI: 10.1021/es0110067] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A recent article presented geochemical and microbial evidence establishing metabolic adaptation to and in-situ reductive dechlorination of trichloroethene (TCE) in a fractured dolomite aquifer. This study was designed to further explore site conditions and microbial populations and to explain previously reported enhancement of reductive dechlorination by the addition of pulverized dolomite to laboratory microcosms. A survey of groundwater geochemical parameters (chlorinated ethenes, ethene, H2, CH4, DIC, DOC, and delta13C values for CH4, DIC, and DOC) indicated that in situ reductive dechlorination was ongoing and that an unidentified pool of organic carbon was contributing, likely via microbial respiration, to the large and relatively light on-site DIC pool. Petroleum hydrocarbons associated with the dolomite rock were analyzed by GC/MS and featured a characteristically low delta13C value. Straight chain hydrocarbons were extracted from the dolomite previously found to stimulate reductive dechlorination; these were particularly depleted in hexadecane (HD). Thus, we hypothesized that HD and related hydrocarbons might be anaerobically respired and serve both as the source of on-site DIC and support reductive dechlorination of TCE. Microcosms amended with pulverized dolomite demonstrated reductive dechlorination, whereas a combusted dolomite amendment did not. HD-amended microcosms were also inactive. Therefore, the stimulatory factor in the pulverized dolomite was heat labile, but that component was not HD. Amplified Ribosomal DNA Restriction Analysis (ARDRA) of the microbial populations in well waters indicated that a relatively low diversity, sulfur-transforming community outside the plume was shifted toward a high diversity community including Dehalococcoides ethenogenes-type microorganisms inside the zone of contamination. These observations illustrate biogeochemical intricacies of in situ reductive dechlorination reactions.
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Affiliation(s)
- A M Hohnstock-Ashe
- Department of Microbiology, Wing Hall Cornell University, Ithaca, New York 14853, USA
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118
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Krasotkina J, Walters T, Maruya KA, Ragsdale SW. Characterization of the B12- and iron-sulfur-containing reductive dehalogenase from Desulfitobacterium chlororespirans. J Biol Chem 2001; 276:40991-7. [PMID: 11533062 DOI: 10.1074/jbc.m106217200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The United Nations and the U.S. Environmental Protection Agency have identified a variety of chlorinated aromatics that constitute a significant health and environmental risk as "priority organic pollutants," the so-called "dirty dozen." Microbes have evolved the ability to utilize chlorinated aromatics as terminal electron acceptors in an energy-generating process called dehalorespiration. In this process, a reductive dehalogenase (CprA), couples the oxidation of an electron donor to the reductive elimination of chloride. We have characterized the B12 and iron-sulfur cluster-containing 3-chloro-4-hydroxybenzoate reductive dehalogenase from Desulfitobacterium chlororespirans. By defining the substrate and inhibitor specificity for the dehalogenase, the enzyme was found to require an hydroxyl group ortho to the halide. Inhibition studies indicate that the hydroxyl group is required for substrate binding. The carboxyl group can be replaced by other functionalities, e.g. acetyl or halide groups, ortho or meta to the chloride to be eliminated. The purified D. chlororespirans enzyme could dechlorinate an hydroxylated PCB (3,3',5,5'-tetrachloro-4,4'-biphenyldiol) at a rate about 1% of that with 3-chloro-4-hydroxybenzoate. Solvent deuterium isotope effect studies indicate that transfer of a single proton is partially rate-limiting in the dehalogenation reaction.
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Affiliation(s)
- J Krasotkina
- Department of Biochemistry, Beadle Center, University of Nebraska, Lincoln, Nebraska 68588-0664, USA
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119
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Seffernick JL, Wackett LP. Rapid evolution of bacterial catabolic enzymes: a case study with atrazine chlorohydrolase. Biochemistry 2001; 40:12747-53. [PMID: 11669610 DOI: 10.1021/bi011293r] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J L Seffernick
- Department of Biochemistry, Molecular Biology, University of Minnesota, St. Paul, Minnesota 55108, USA
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120
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Chang YC, Okeke BC, Hatsu M, Takamizawa K. In vitro dehalogenation of tetrachloroethylene (PCE) by cell-free extracts of Clostridium bifermentans DPH-1. BIORESOURCE TECHNOLOGY 2001; 78:141-147. [PMID: 11333032 DOI: 10.1016/s0960-8524(01)00005-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Cell-free extracts of Clostridium bifermentans DPH-1 catalyzed tetrachloroethylene (PCE) dechlorination. PCE degradation was stimulated by addition of a variety of electron donors. Ethanol (0.61 mM) was the most effective electron donor for PCE dechlorination. Maximum activity was recorded at 30 degrees C and pH 7.5. Addition of NADH as a cofactor stimulated enzymatic activity but the activity was not stimulated by addition of metal ions. When the cell-free enzyme extract was incubated in the presence of titanium citrate as a reducing agent, the dehalogenase was rapidly inactivated by propyl iodide (0.5 mM). The activity of propyliodide-reacted enzyme was restored by illumination with a 250 W lamp. The dehalogenase activity was also inhibited by cyanide. The substrate spectrum of activity included trichloroethylene (TCE), cis-1,2-dichloroethylene (cDCE), trans-dichloroethylene, 1,1-dichloroethylene, 1,2-dichloroethane, and 1,1,2-trichloroethane. The highest rate of degradation of the chlorinated aliphatic compounds was achieved with PCE, and PCE was principally degraded via TCE to cDCE. Results indicate that the dehalogenase could play a vital role in the breakdown of PCE as well as a variety of other chlorinated aliphatic compounds.
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Affiliation(s)
- Y C Chang
- Department of Bioprocessing, Faculty of Agriculture, Gifu University, Yanagido, Japan
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121
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Okeke BC, Chang YC, Hatsu M, Suzuki T, Takamizawa K. Purification, cloning, and sequencing of an enzyme mediating the reductive dechlorination of tetrachloroethylene (PCE) fromClostridium bifermentansDPH-1. Can J Microbiol 2001. [DOI: 10.1139/w01-048] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An enzyme mediating the reductive dechlorination of tetrachloroethylene (PCE) from cell-free extracts of Clostridium bifermentans DPH-1 was purified, cloned, and sequenced. The enzyme catalyzed the reductive dechlorination of PCE to cis-1,2-dichloroethylene via trichloroethylene, at a Vmaxand Kmof 73 nmol/mg protein and 12 µM, respectively. Maximal activity was recorded at 35°C and pH 7.5. Enzymatic activity was independent of metal ions but was oxygen sensitive. A mixture of propyl iodide and titanium citrate caused a light-reversible inhibition of enzymatic activity suggesting the involvement of a corrinoid cofactor. The molecular mass of the native enzyme was estimated to be approximately 70 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption ionization-time of flight/mass spectrometry (MALDITOF/MS) revealed molecular masses of approximately 35 kDa and 35.7 kDa, respectively. A broad spectrum of chlorinated aliphatic compounds (PCE, trichloroethylene, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1,1-dichloroethylene, 1,2-dichloropropane, and 1,1,2-trichloroethane) was degraded. With degenerate primers designed from the N-terminal sequence (27 amino acid residues), a partial sequence (81 bp) of the encoding gene was amplified by polymerase chain reaction (PCR) and sequenced. Southern analysis of C. bifermentans genomic DNA using the PCR product as a probe revealed restriction fragment bands. A 5.0 kb ClaI fragment, harboring the relevant gene (designated pceC) was cloned (pDEHAL5) and the complete nucleotide sequence of pceC was determined. The gene showed homology mainly with microbial membrane proteins and no homology with any known dehalogenase, suggesting a distinct PCE dehalogenase.Key words: tetrachloroethylene, Clostridium bifermentans DPH-1, PCE dehalogenase, gene cloning.
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122
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van Hylckama Vlieg JE, Janssen DB. Formation and detoxification of reactive intermediates in the metabolism of chlorinated ethenes. J Biotechnol 2001; 85:81-102. [PMID: 11165358 DOI: 10.1016/s0168-1656(00)00364-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Short-chain halogenated aliphatics, such as chlorinated ethenes, constitute a large group of priority pollutants. This paper gives an overview on the chemical and physical properties of chlorinated aliphatics that are critical in determining their toxicological characteristics and recalcitrance to biodegradation. The toxic effects and principle metabolic pathways of halogenated ethenes in mammals are briefly discussed. Furthermore, the bacterial degradation of halogenated compounds is reviewed and it is described how product toxicity may explain why most chlorinated ethenes are only degraded cometabolically under aerobic conditions. The cometabolic degradation of chlorinated ethenes by oxygenase-producing microorganisms has been extensively studied. The physiology and bioremediation potential of methanotrophs has been well characterized and an overview of the available data on these organisms is presented. The sensitivity of methanotrophs to product toxicity is a major limitation for the transformation of chlorinated ethenes by these organisms. Most toxic effects arise from the inability to detoxify the reactive chlorinated epoxyethanes occurring as primary metabolites. Therefore, the last part of this review focuses on the metabolic reactions and enzymes that are involved in the detoxification of epoxides in mammals. A key role is played by glutathione S-transferases. Furthermore, an overview is presented on the current knowledge about bacterial enzymes involved in the metabolism of epoxides. Such enzymes might be useful for detoxifying chlorinated ethene epoxides and an example of a glutathione S-transferase with activity for dichloroepoxyethane is highlighted.
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Affiliation(s)
- J E van Hylckama Vlieg
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, NL-9747 AG, Groningen, The Netherlands
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123
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Maymó-Gatell X, Nijenhuis I, Zinder SH. Reductive dechlorination of cis-1,2-dichloroethene and vinyl chloride by "Dehalococcoides ethenogenes". ENVIRONMENTAL SCIENCE & TECHNOLOGY 2001; 35:516-521. [PMID: 11351722 DOI: 10.1021/es001285i] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
cis-Dichloroethene (DCE) and vinyl chloride (VC) often accumulate in contaminated aquifers in which tetrachloroethene (PCE) or trichloroethene (TCE) undergo reductive dechlorination. "Dehalococcoides ethenogenes" strain 195 is the first isolate capable of dechlorinating chloroethenes past cis-DCE. Strain 195 could utilize commercially synthesized cis-DCE as an electron acceptor, but doses greater than 0.2 mmol/L were inhibitory, especially to PCE utilization. To test whether the cis-DCE itself was toxic, or whether the toxicity was due to impurities in the commercial preparation (97% nominal purity), we produced cis-DCE biologically from PCE using a Desulfitobacterium sp. culture. The biogenic cis-DCE was readily utilized at high concentrations by strain 195 indicating that cis-DCE was not intrinsically inhibitory. Analysis of the commercially synthesized cis-DCE by GC/mass spectrometry indicated the presence of approximately 0.4% mol/mol chloroform. Chloroform was found to be inhibitory to chloroethene utilization by strain 195 and at least partially accounts for the inhibitory activity of the synthetic cis-DCE. VC, a human carcinogen that accumulates to a large extent in cultures of strain 195, was not utilized as a growth substrate, and cultures inoculated into medium with VC required a growth substrate, such as PCE, for substantial VC dechlorination. However, high concentrations of PCE or TCE inhibited VC dechlorination. Use of a hexadecane phase to keep the aqueous PCE concentration low in cultures allowed simultaneous utilization of PCE and VC. At contaminated sites in which "D. ethenogenes" or similar organisms are present, biogenic cis-DCE should be readily dechlorinated, chloroform as a co-contaminant may be inhibitory, and concentrations of PCE and TCE, except perhaps those near the source zone, should allow substantial VC dechlorination.
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Affiliation(s)
- X Maymó-Gatell
- Department of Microbiology, Wing Hall, Cornell University, Ithaca, New York 14853, USA.
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124
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Shey J, van der Donk WA. Mechanistic Studies on the Vitamin B12-Catalyzed Dechlorination of Chlorinated Alkenes. J Am Chem Soc 2000. [DOI: 10.1021/ja0055965] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Justin Shey
- Department of Chemistry University of Illinois at Urbana−Champaign 600 South Mathews Avenue, Urbana, Illinois 61801
| | - Wilfred A. van der Donk
- Department of Chemistry University of Illinois at Urbana−Champaign 600 South Mathews Avenue, Urbana, Illinois 61801
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125
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Abstract
Tetrachloroethene is a frequent groundwater contaminant often persisting in the subsurface environments. It is recalcitrant under aerobic conditions because it is in a highly oxidized state and is not readily susceptible to oxidation. Nevertheless, at least 15 organisms from different metabolic groups, viz. halorespirators (9), acetogens (2), methanogens (3) and facultative anaerobes (2), that are able to metabolize tetrachloroethene have been isolated as axenic cultures to-date. Some of these organisms couple dehalo-genation to energy conservation and utilize tetrachloroethene as the only source of energy while others dehalogenate tetrachloroethene fortuitously. Halorespiring organisms (halorespirators) utilize halogenated organic compounds as electron acceptors in an anaerobic respiratory process. Different organisms exhibit differences in the final products of tetrachloroethene dehalogenation, some strains convert tetrachloroethene to trichloroethene only, while others also carry out consecutive dehalogenation to dichloroethenes and vinyl chloride. Thus far, only a single organism, 'Dehalococcoides ethenogenes' strain 195, has been isolated which dechlorinates tetrachloroethene all the way down to ethylene. The majority of tetrachloroethene-dehalogenating organisms have been isolated only in the past few years and several of them, i.e., Dehalobacter restrictus, Desulfitobacterium dehalogenans, 'Dehalococcoides ethenogenes', 'Dehalospirillum multivorans', Desulfuromonas chloroethenica, and Desulfomonile tiedjei, are representatives of new taxonomic groups. This contribution summarizes the available information regarding the axenic cultures of the tetrachloroethene-dehalogenating bacteria. The present knowledge about the isolation of these organisms, their physiological characteristics, morphology, taxonomy and their ability to dechlorinate tetrachloroethene is presented to facilitate a comprehensive comparison.
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Affiliation(s)
- J Damborský
- Laboratory of Biomolecular Structure and Dynamics, Faculty of Science, Masaryk University, Brno, Czech Republic.
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126
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van de Pas BA, Smidt H, Hagen WR, van der Oost J, Schraa G, Stams AJ, de Vos WM. Purification and molecular characterization of ortho-chlorophenol reductive dehalogenase, a key enzyme of halorespiration in Desulfitobacterium dehalogenans. J Biol Chem 1999; 274:20287-92. [PMID: 10400648 DOI: 10.1074/jbc.274.29.20287] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ortho-Chlorophenol reductive dehalogenase of the halorespiring Gram-positive Desulfitobacterium dehalogenans was purified 90-fold to apparent homogeneity. The purified dehalogenase catalyzed the reductive removal of a halogen atom from the ortho position of 3-chloro-4-hydroxyphenylacetate, 2-chlorophenol, 2,3-dichlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, pentachlorophenol, and 2-bromo-4-chlorophenol with reduced methyl viologen as electron donor. The dechlorination of 3-chloro-4-hydroxyphenylacetate was catalyzed by the enzyme at a Vmax of 28 units/mg protein and a Km of 20 microM. The pH and temperature optimum were 8.2 and 52 degrees C, respectively. EPR analysis indicated one [4Fe-4S] cluster (midpoint redox potential (Em) = -440 mV), one [3Fe-4S] cluster (Em = +70 mV), and one cobalamin per 48-kDa monomer. The Co(I)/Co(II) transition had an Em of -370 mV. Via a reversed genetic approach based on the N-terminal sequence, the corresponding gene was isolated from a D. dehalogenans genomic library, cloned, and sequenced. This revealed the presence of two closely linked genes: (i) cprA, encoding the o-chlorophenol reductive dehalogenase, which contains a twin-arginine type signal sequence that is processed in the purified enzyme; (ii) cprB, coding for an integral membrane protein that could act as a membrane anchor of the dehalogenase. This first biochemical and molecular characterization of a chlorophenol reductive dehalogenase has revealed structural resemblance with haloalkene reductive dehalogenases.
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Affiliation(s)
- B A van de Pas
- Laboratory of Microbiology, Wageningen University, Hesselink van Suchtelenweg 4, NL-6703 CT Wageningen, The Netherlands. Bran,
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127
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Kunishima M, Friedman JE, Rokita SE. Transition-State Stabilization by a Mammalian Reductive Dehalogenase. J Am Chem Soc 1999. [DOI: 10.1021/ja990693n] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Munetaka Kunishima
- Department of Chemistry and Biochemistry University of Maryland College Park, Maryland 20742
| | - Jessica E. Friedman
- Department of Chemistry and Biochemistry University of Maryland College Park, Maryland 20742
| | - Steven E. Rokita
- Department of Chemistry and Biochemistry University of Maryland College Park, Maryland 20742
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128
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Louie TM, Mohn WW. Evidence for a chemiosmotic model of dehalorespiration in Desulfomonile tiedjei DCB-1. J Bacteriol 1999; 181:40-6. [PMID: 9864310 PMCID: PMC103529 DOI: 10.1128/jb.181.1.40-46.1999] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/1998] [Accepted: 10/19/1998] [Indexed: 11/20/2022] Open
Abstract
Desulfomonile tiedjei DCB-1, a sulfate-reducing bacterium, conserves energy for growth from reductive dehalogenation of 3-chlorobenzoate by an uncharacterized chemiosmotic process. Respiratory electron transport components were examined in D. tiedjei cells grown under conditions for reductive dehalogenation, pyruvate fermentation, and sulfate reduction. Reductive dehalogenation was inhibited by the respiratory quinone inhibitor 2-heptyl-4-hydroxyquinoline N-oxide, suggesting that a respiratory quinoid is a component of the electron transport chain coupled to reductive dehalogenation. Moreover, reductive dehalogenation activity was dependent on 1, 4-naphthoquinone, a possible precursor for a respiratory quinoid. However, no ubiquinone or menaquinone could be extracted from D. tiedjei. Rather, a UV-absorbing quinoid which is different from common respiratory quinones in chemical structure according to mass spectrometric and UV absorption spectroscopic analyses was extracted. ATP sulfurylase, adenosine phosphosulfate reductase, and desulfoviridin sulfite reductase, enzymes involved in sulfate reduction, were constitutively expressed in the cytoplasm of D. tiedjei cells grown under all three metabolic conditions. A periplasmic hydrogenase was detected in cells grown under reductive-dehalogenating and pyruvate-fermenting conditions. A membrane-bound, periplasm-oriented formate dehydrogenase was detected only in cells grown with formate as electron donor, while a cytoplasmic formate dehydrogenase was detected in cells grown under reductive-dehalogenating and pyruvate-fermenting conditions. Results from dehalogenation assays with D. tiedjei whole-cell suspensions and cell extracts suggest that the membrane-bound reductive dehalogenase is cytoplasm oriented. The data clearly demonstrate an enzyme topology in D. tiedjei which produces protons directly in the periplasm, generating a proton motive force by a scalar mechanism.
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Affiliation(s)
- T M Louie
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
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129
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Holliger C, Wohlfarth G, Diekert G. Reductive dechlorination in the energy metabolism of anaerobic bacteria. FEMS Microbiol Rev 1998. [DOI: 10.1111/j.1574-6976.1998.tb00377.x] [Citation(s) in RCA: 299] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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130
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Christiansen N, Ahring BK, Wohlfarth G, Diekert G. Purification and characterization of the 3-chloro-4-hydroxy-phenylacetate reductive dehalogenase of Desulfitobacterium hafniense. FEBS Lett 1998; 436:159-62. [PMID: 9781670 DOI: 10.1016/s0014-5793(98)01114-4] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The membrane-bound 3-chloro-4-hydroxyphenylacetate (Cl-OHPA) reductive dehalogenase from the chlorophenol-reducing anaerobe Desulfitobacterium hafniense was purified 11.3-fold to apparent homogeneity in the presence of the detergent CHAPS. The purified dehalogenase catalyzed the reductive dechlorination of Cl-OHPA to 4-hydroxyphenylacetate with reduced methyl viologen as the electron donor at a specific activity of 103.2 nkat/mg protein. SDS-PAGE revealed a single protein band with an apparent molecular mass of 46.5 kDa. The enzyme contained 0.68 +/- 0.2 mol corrinoid, 12.0 +/- 0.7 mol iron, and 13.0 +/- 0.7 mol acid-labile sulfur per mol subunit. The N-terminal amino acid sequence of the enzyme was determined and no significant similarity was found to any protein present in the gene bank.
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Affiliation(s)
- N Christiansen
- Department of Biotechnology, Technical University of Denmark, Lyngby
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131
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Abstract
Microbial dehalogenases are involved in the biodegradation of many important chlorinated pollutants. Some recent studies of haloalkane dehalogenase, dichloromethane dehalogenase, tetrachlorohydroquinone dehalogenase and perchloroethylene and trichloroethylene reductive dehalogenases have addressed the issue of recruitment and adaptation of proteins to dehalogenate novel substrates.
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Affiliation(s)
- S D Copley
- University of Colorado at Boulder, Department of Chemistry and Biochemistry 80309, USA.
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132
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Neumann A, Wohlfarth G, Diekert G. Tetrachloroethene dehalogenase from Dehalospirillum multivorans: cloning, sequencing of the encoding genes, and expression of the pceA gene in Escherichia coli. J Bacteriol 1998; 180:4140-5. [PMID: 9696761 PMCID: PMC107409 DOI: 10.1128/jb.180.16.4140-4145.1998] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/1997] [Accepted: 06/05/1998] [Indexed: 11/20/2022] Open
Abstract
The genes encoding tetrachloroethene reductive dehalogenase, a corrinoid-Fe/S protein, of Dehalospirillum multivorans were cloned and sequenced. The pceA gene is upstream of pceB and overlaps it by 4 bp. The presence of a sigma70-like promoter sequence upstream of pceA and of a rho-independent terminator downstream of pceB indicated that both genes are cotranscribed. This assumption is supported by reverse transcriptase PCR data. The pceA and pceB genes encode putative 501- and 74-amino-acid proteins, respectively, with calculated molecular masses of 55,887 and 8,354 Da, respectively. Four peptides obtained after trypsin treatment of tetrachloroethene (PCE) dehalogenase were found in the deduced amino acid sequence of pceA. The N-terminal amino acid sequence of the PCE dehalogenase isolated from D. multivorans was found 30 amino acids downstream of the N terminus of the deduced pceA product. The pceA gene contained a nucleotide stretch highly similar to binding motifs for two Fe4S4 clusters or for one Fe4S4 cluster and one Fe3S4 cluster. A consensus sequence for the binding of a corrinoid was not found in pceA. No significant similarities to genes in the databases were detected in sequence comparisons. The pceB gene contained two membrane-spanning helices as indicated by two hydrophobic stretches in the hydropathic plot. Sequence comparisons of pceB revealed no sequence similarities to genes present in the databases. Only in the presence of pUBS 520 supplying the recombinant bacteria with high levels of the rare Escherichia coli tRNA4Arg was pceA expressed, albeit nonfunctionally, in recombinant E. coli BL21 (DE3).
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Affiliation(s)
- A Neumann
- Institut für Mikrobiologie der Universität Stuttgart, Stuttgart, Germany
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133
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Magnuson JK, Stern RV, Gossett JM, Zinder SH, Burris DR. Reductive dechlorination of tetrachloroethene to ethene by a two-component enzyme pathway. Appl Environ Microbiol 1998; 64:1270-5. [PMID: 10671186 PMCID: PMC106140 DOI: 10.1128/aem.64.4.1270-1275.1998] [Citation(s) in RCA: 222] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/1997] [Accepted: 01/21/1998] [Indexed: 11/20/2022] Open
Abstract
Two membrane-bound, reductive dehalogenases that constitute a novel pathway for complete dechlorination of tetrachloroethene (perchloroethylene [PCE]) to ethene were partially purified from an anaerobic microbial enrichment culture containing Dehalococcoides ethenogenes 195. When titanium (III) citrate and methyl viologen were used as reductants, PCE-reductive dehalogenase (PCE-RDase) (51 kDa) dechlorinated PCE to trichloroethene (TCE) at a rate of 20 micromol/min/mg of protein. TCE-reductive dehalogenase (TCE-RDase) (61 kDa) dechlorinated TCE to ethene. TCE, cis-1,2-dichloroethene, and 1,1-dichloroethene were dechlorinated at similar rates, 8 to 12 micromol/min/mg of protein. Vinyl chloride and trans-1,2-dichloroethene were degraded at rates which were approximately 2 orders of magnitude lower. The light-reversible inhibition of TCE-RDase by iodopropane and the light-reversible inhibition of PCE-RDase by iodoethane suggest that both of these dehalogenases contain Co(I) corrinoid cofactors. Isolation and characterization of these novel bacterial enzymes provided further insight into the catalytic mechanisms of biological reductive dehalogenation.
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Affiliation(s)
- J K Magnuson
- USAF Armstrong Laboratory, Tyndall Air Force Base, Florida 32403-5323, USA.
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134
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Affiliation(s)
- Bernard Meunier
- Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse, Cedex 4, France
| | - Alexander Sorokin
- Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse, Cedex 4, France
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Townsend GT, Suflita JM. Influence of sulfur oxyanions on reductive dehalogenation activities in Desulfomonile tiedjei. Appl Environ Microbiol 1997; 63:3594-9. [PMID: 9293011 PMCID: PMC168666 DOI: 10.1128/aem.63.9.3594-3599.1997] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The inhibition of aryl reductive dehalogenation reactions by sulfur oxyanions has been demonstrated in environmental samples, dehalogenating enrichments, and the sulfate-reducing bacterium Desulfomonile tiedjei; however, this phenomenon is not well understood. We examined the effects of sulfate, sulfite, and thiosulfate on reductive dehalogenation in the model microorganism D. tiedjei and found separate mechanisms of inhibition due to these oxyanions under growth versus nongrowth conditions. Dehalogenation activity was greatly reduced in extracts of cells grown in the presence of both 3-chlorobenzoate, the substrate or inducer for the aryl dehalogenation activity, and either sulfate, sulfite, or thiosulfate, indicating that sulfur oxyanions repress the requisite enzymes. In extracts of fully induced cells, thiosulfate and sulfite, but not sulfate, were potent inhibitors of aryl dehalogenation activity even in membrane fractions lacking the cytoplasmically located sulfur oxyanion reductase. These results suggest that under growth conditions, sulfur oxyanions serve as preferred electron acceptors and negatively influence dehalogenation activity in D. tiedjei by regulating the amount of active aryl dehalogenase in cells. Additionally, in vitro inhibition by sulfur oxyanions is due to the interaction of the reactive species with enzymes involved in dehalogenation and need not involve competition between two respiratory processes for reducing equivalents. Sulfur oxyanions also inhibited tetrachloroethylene dehalogenation by the same mechanisms, further indicating that chloroethylenes are fortuitously dehalogenated by the aryl dehalogenase. The commonly observed inhibition of reductive dehalogenation reactions under sulfate-reducing conditions may be due to similar regulation mechanisms in other dehalogenating microorganisms that contain multiple respiratory activities.
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Affiliation(s)
- G T Townsend
- Department of Botany and Microbiology, University of Oklahoma, Norman 73019, USA
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Holliger C, Gaspard S, Glod G, Heijman C, Schumacher W, Schwarzenbach RP, Vazquez F. Contaminated environments in the subsurface and bioremediation: organic contaminants. FEMS Microbiol Rev 1997; 20:517-23. [PMID: 9299718 DOI: 10.1111/j.1574-6976.1997.tb00334.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Due to leakages, spills, improper disposal and accidents during transport, organic compounds have become subsurface contaminants that threaten important drinking water resources. One strategy to remediate such polluted subsurface environments is to make use of the degradative capacity of bacteria. It is often sufficient to supply the subsurface with nutrients such as nitrogen and phosphorus, and aerobic treatments are still dominating. However, anaerobic processes have advantages such as low biomass production and good electron acceptor availability, and they are sometimes the only possible solution. This review will focus on three important groups of environmental organic contaminants: hydrocarbons, chlorinated and nitroaromatic compounds. Whereas hydrocarbons are oxidized and completely mineralized under anaerobic conditions in the presence of electron acceptors such as nitrate, iron, sulfate and carbon dioxide, chlorinated and nitroaromatic compounds are reductively transformed. For the aerobic often persistent polychlorinated compounds, reductive dechlorination leads to harmless products or to compounds that are aerobically degradable. The nitroaromatic compounds are first reductively transformed to the corresponding amines and can subsequently be bound to the humic fraction in an aerobic process. Such new findings and developments give hope that in the near future contaminated aquifers can efficiently be remediated, a prerequisite for a sustainable use of the precious-subsurface drinking water resources.
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Affiliation(s)
- C Holliger
- Swiss Federal Institute for Environmental Science and Technology (EAWAG), Limnological Research Center, Kastanienbaum, Switzerland.
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137
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Schumacher W, Holliger C, Zehnder AJ, Hagen WR. Redox chemistry of cobalamin and iron-sulfur cofactors in the tetrachloroethene reductase of Dehalobacter restrictus. FEBS Lett 1997; 409:421-5. [PMID: 9224702 DOI: 10.1016/s0014-5793(97)00520-6] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Respiration of Dehalobacter restrictus is based on reductive dechlorination of tetrachloroethene. The terminal component of the respiratory chain is the membrane-bound tetrachloroethene reductase. The metal prosthetic groups of the purified enzyme have been studied by optical and EPR spectroscopy. The 60-kDa monomer contains one cobalamin with Em(Co[1+/2+]) = -350 mV and Em(Co[2+/3+]) > 150 mV and two electron-transferring [4Fe-4S](2+;1+) clusters with rather low redox potentials of Em approximately -480 mV. The cob(II)alamin is present in the base-off configuration. A completely reduced enzyme sample reacted very rapidly with tetrachloroethene yielding base-off cob(II)alamin rather than trichlorovinyl-cob(III)alamin.
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Affiliation(s)
- W Schumacher
- Swiss Federal Institute for Environmental Science and Technology (EAWAG), Limnological Research Center, Kastanienbaum
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138
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Abstract
Several anaerobic bacteria are able to reductively dehalogenate chlorinated hydrocarbons and to couple this reaction to the synthesis of ATP via a chemiosmotic mechanism (dehalorespiration). A few reductive dehalogenases have recently been purified and characterized. Preliminary investigations have been performed to elucidate the mechanism of dehalorespiration.
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Affiliation(s)
- G Wohlfarth
- Institute of Microbiology, University of Stuttgart, Germany.
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139
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Miller E, Wohlfarth G, Diekert G. Studies on tetrachloroethene respiration in Dehalospirillum multivorans. Arch Microbiol 1996; 166:379-87. [PMID: 9082914 DOI: 10.1007/bf01682983] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Tetrachloroethene (PCE) respiration was studied in the tetrachloroethene-utilizing anaerobe, Dehalospirillum multivorans, with respect to localization of the catabolic enzymes, the electron carriers potentially involved in electron transport, and the response to ionophores and specific inhibitors. Hydrogenase and formate dehydrogenase were recovered in the periplasmic cell fraction and were membrane-associated. Electron-accepting tetrachloroethene dehalogenase was found in the cytoplasmic fraction. In the PCE dehalogenase assay, only artificial electron donors with a standard redox potential of D. multivorans (Eo' = -445 mV) could serve as electron donor for PCE reduction. However, the reaction rate with ferredoxin was only 1% of that with methyl viologen, whereas the pyruvate-ferredoxin oxidoreductase exhibited almost the same reaction rates with methyl viologen and ferredoxin as electron acceptors for pyruvate oxidation. Reduced menadione (2-methyl-1, 4-naphthoquinone) did not serve as electron donor in the PCE dehalogenase reaction. 2-Heptyl-4-hydroxyquinoline-N-oxide (HOQNO) had no significant effect on PCE dechlorination in cell suspensions and in crude extracts. Whole cells catalyzed the reductive dechlorination of PCE with H2 or formate as electron donors. The dechlorination in cell suspensions rather than in cell extracts was inhibited by the ionophores carbonylcyanide-p-(trifluoromethoxy)phenylhydrazone (FCCP) and tetrachlorosalicylanilide (TCS), indicating that a membrane potential and/or a pH gradient may be required for the reaction in vivo.
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Affiliation(s)
- E Miller
- Institut für Mikrobiologie, Universität Stuttgart, Allmandring 31, D-70550 Stuttgart, Germany
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