scholarly journals Reconstructed genomes of novel Dehalococcoides mccartyi strains from 1,2,3,4-tetrachlorodibenzo-p-dioxin-dechlorinating enrichment cultures reveal divergent reductive dehalogenase gene profiles

2017 ◽  
Vol 93 (12) ◽  
Author(s):  
Hang T. Dam ◽  
John Vollmers ◽  
Anne-Kristin Kaster ◽  
Max M. Häggblom
Keyword(s):  
Reductive Dehalogenase ◽  
Dehalococcoides Mccartyi ◽  
Enrichment Cultures ◽  
Gene Profiles ◽  
Tetrachlorodibenzo P Dioxin ◽  
Dehalogenase Gene

scholarly journals Extrachromosomal circular elements targeted by CRISPR-Cas in Dehalococcoides mccartyi are linked to mobilization of reductive dehalogenase genes

2018 ◽  
Vol 13 (1) ◽  
pp. 24-38 ◽  
Author(s):  
Olivia Molenda ◽  
Shuiquan Tang ◽  
Line Lomheim ◽  
Vasu K. Gautam ◽  
Sofia Lemak ◽  
...  
Keyword(s):  
Reductive Dehalogenase ◽  
Dehalococcoides Mccartyi ◽  
Reductive Dehalogenase Genes

scholarly journals Unexpected Specificity of Interspecies Cobamide Transfer from Geobacter spp. to Organohalide-Respiring Dehalococcoides mccartyi Strains

2012 ◽  
Vol 78 (18) ◽  
pp. 6630-6636 ◽  
Author(s):  
Jun Yan ◽  
Kirsti M. Ritalahti ◽  
Darlene D. Wagner ◽  
Frank E. Löffler
Keyword(s):  
Reductive Dechlorination ◽  
De Novo ◽  
Synthetic Medium ◽  
Geobacter Sulfurreducens ◽  
Rrna Gene ◽  
Content Type ◽  
Reductive Dehalogenase ◽  
Dehalococcoides Mccartyi ◽  
Gene Copies ◽  
Pure Cultures

ABSTRACTDehalococcoides mccartyistrains conserve energy from reductive dechlorination reactions catalyzed by corrinoid-dependent reductive dehalogenase enzyme systems.Dehalococcoideslacks the ability forde novocorrinoid synthesis, and pure cultures require the addition of cyanocobalamin (vitamin B12) for growth. In contrast,Geobacter lovleyi, which dechlorinates tetrachloroethene tocis-1,2-dichloroethene (cis-DCE), and the nondechlorinating speciesGeobacter sulfurreducenshave complete sets of cobamide biosynthesis genes and produced 12.9 ± 2.4 and 24.2 ± 5.8 ng of extracellular cobamide per liter of culture suspension, respectively, during growth with acetate and fumarate in a completely synthetic medium.G. lovleyi-D. mccartyistrain BAV1 or strain FL2 cocultures provided evidence for interspecies corrinoid transfer, andcis-DCE was dechlorinated to vinyl chloride and ethene concomitant withDehalococcoidesgrowth. In contrast, negligible increase inDehalococcoides16S rRNA gene copies and insignificant dechlorination occurred inG. sulfurreducens-D. mccartyistrain BAV1 or strain FL2 cocultures. Apparently,G. lovleyiproduces a cobamide that complementsDehalococcoides' nutritional requirements, whereasG. sulfurreducensdoes not. Interestingly,Dehalococcoidesdechlorination activity and growth could be restored inG. sulfurreducens-Dehalococcoidescocultures by adding 10 μM 5′,6′-dimethylbenzimidazole. Observations made with theG. sulfurreducens-Dehalococcoidescocultures suggest that the exchange of the lower ligand generated a cobalamin, which supportedDehalococcoidesactivity. These findings have implications forin situbioremediation and suggest that the corrinoid metabolism ofDehalococcoidesmust be understood to faithfully predict, and possibly enhance, reductive dechlorination activities.

scholarly journals Functional Characterization of Reductive Dehalogenases by Using Blue Native Polyacrylamide Gel Electrophoresis

2012 ◽  
Vol 79 (3) ◽  
pp. 974-981 ◽  
Author(s):  
Shuiquan Tang ◽  
Winnie W. M. Chan ◽  
Kelly E. Fletcher ◽  
Jana Seifert ◽  
Xiaoming Liang ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Functional Characterization ◽  
Polyacrylamide Gel ◽  
Content Type ◽  
Reductive Dehalogenase ◽  
Dehalococcoides Mccartyi ◽  
Native Polyacrylamide Gel Electrophoresis ◽  
Rdase Genes ◽  
Blue Native

ABSTRACTDehalococcoides mccartyistrains are obligate organohalide-respiring bacteria harboring multiple distinct reductive dehalogenase (RDase) genes within their genomes. A major challenge is to identify substrates for the enzymes encoded by these RDase genes. We demonstrate an approach that involves blue native polyacrylamide gel electrophoresis (BN-PAGE) followed by enzyme activity assays with gel slices and subsequent identification of proteins in gel slices using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). RDase expression was investigated in cultures ofDehalococcoides mccartyistrain BAV1 and in the KB-1 consortium growing on chlorinated ethenes and 1,2-dichloroethane. In cultures of strain BAV1, BvcA was the only RDase detected, revealing that this enzyme catalyzes the dechlorination not only of vinyl chloride, but also of all dichloroethene isomers and 1,2-dichloroethane. In cultures of consortium KB-1, five distinctDehalococcoidesRDases and oneGeobacterRDase were expressed under the conditions tested. Three of the five RDases included orthologs to the previously identified chlorinated ethene-dechlorinating enzymes VcrA, BvcA, and TceA. This study revealed substrate promiscuity for these three enzymes and provides a path forward to further explore the largely unknown RDase protein family.

scholarly journals Dehalococcoides mccartyi Strain DCMB5 Respires a Broad Spectrum of Chlorinated Aromatic Compounds

2014 ◽  
Vol 81 (2) ◽  
pp. 587-596 ◽  
Author(s):  
Marlén Pöritz ◽  
Christian L. Schiffmann ◽  
Gerd Hause ◽  
Ulrike Heinemann ◽  
Jana Seifert ◽  
...  
Keyword(s):  
Electron Acceptor ◽  
Aromatic Compounds ◽  
Lag Phase ◽  
Organohalide Respiration ◽  
Content Type ◽  
Reductive Dehalogenase ◽  
Dehalococcoides Mccartyi ◽  
Type Iv ◽  
Transmission Electron ◽  
Almost All

ABSTRACTPolyhalogenated aromatic compounds are harmful environmental contaminants and tend to persist in anoxic soils and sediments.Dehalococcoides mccartyistrain DCMB5, a strain originating from dioxin-polluted river sediment, was examined for its capacity to dehalogenate diverse chloroaromatic compounds. Strain DCMB5 used hexachlorobenzenes, pentachlorobenzenes, all three tetrachlorobenzenes, and 1,2,3-trichlorobenzene as well as 1,2,3,4-tetra- and 1,2,4-trichlorodibenzo-p-dioxin as electron acceptors for organohalide respiration. In addition, 1,2,3-trichlorodibenzo-p-dioxin and 1,3-, 1,2-, and 1,4-dichlorodibenzo-p-dioxin were dechlorinated, the latter to the nonchlorinated congener with a remarkably short lag phase of 1 to 4 days following transfer. Strain DCMB5 also dechlorinated pentachlorophenol and almost all tetra- and trichlorophenols. Tetrachloroethene was dechlorinated to trichloroethene and served as an electron acceptor for growth. To relate selected dechlorination activities to the expression of specific reductive dehalogenase genes, the proteomes of 1,2,3-trichlorobenzene-, pentachlorobenzene-, and tetrachloroethene-dechlorinating cultures were analyzed. Dcmb_86, an ortholog of the chlorobenzene reductive dehalogenase CbrA, was the most abundant reductive dehalogenase during growth with each electron acceptor, suggesting its pivotal role in organohalide respiration of strain DCMB5. Dcmb_1041 was specifically induced, however, by both chlorobenzenes, whereas 3 putative reductive dehalogenases, Dcmb_1434, Dcmb_1339, and Dcmb_1383, were detected only in tetrachloroethene-grown cells. The proteomes also harbored a type IV pilus protein and the components for its assembly, disassembly, and secretion. In addition, transmission electron microscopy of DCMB5 revealed an irregular mode of cell division as well as the presence of pili, indicating that pilus formation is a feature ofD. mccartyiduring organohalide respiration.

scholarly journals Complete Genome Sequence of Dehalococcoides mccartyi Strain FL2, a Trichloroethene-Respiring Anaerobe Isolated from Pristine Freshwater Sediment

2019 ◽  
Vol 8 (33) ◽  
Author(s):  
Jun Yan ◽  
Yi Yang ◽  
Xiuying Li ◽  
Frank E. Löffler
Keyword(s):  
Complete Genome Sequence ◽  
Reductive Dechlorination ◽  
Complete Genome ◽  
Hydrogen Oxidation ◽  
Protein Coding ◽  
Coding Sequences ◽  
Content Type ◽  
Reductive Dehalogenase ◽  
Dehalococcoides Mccartyi ◽  
Reductive Dehalogenase Genes

Dehalococcoides mccartyi strain FL2 couples growth to hydrogen oxidation and reductive dechlorination of trichloroethene and cis- and trans-1,2-dichloroethenes. Strain FL2 has a 1.42-Mb genome with a G+C content of 47.0% and carries 1,465 protein-coding sequences, including 24 reductive dehalogenase genes.

scholarly journals The MarR-Type Regulator Rdh2R RegulatesrdhGene Transcription in Dehalococcoides mccartyi Strain CBDB1

2016 ◽  
Vol 198 (23) ◽  
pp. 3130-3141 ◽  
Author(s):  
Lydia Krasper ◽  
Hauke Lilie ◽  
Anja Kublik ◽  
Lorenz Adrian ◽  
Ralph Golbik ◽  
...  
Keyword(s):  
Heterologous Expression ◽  
Direct Repeat ◽  
Negative Regulator ◽  
Control Of Gene Expression ◽  
Organohalide Respiration ◽  
Content Type ◽  
Reductive Dehalogenase ◽  
Dehalococcoides Mccartyi ◽  
Transcriptional Start Sites

ABSTRACTReductive dehalogenases are essential enzymes in organohalide respiration and consist of a catalytic subunit A and a membrane protein B, encoded byrdhABgenes. Thirty-twordhABgenes exist in the genome ofDehalococcoides mccartyistrain CBDB1. To gain a first insight into the regulation ofrdhoperons, the control of gene expression of twordhABgenes (cbdbA1453/cbdbA1452 and cbdbA1455/cbdbA1454) by the MarR-type regulator Rdh2R (cbdbA1456) encoded directly upstream was studied using heterologous expression andin vitrostudies. Promoter-lacZreporter fusions were generated and integrated into the genome of theEscherichia colihost. ThelacZreporter activities of bothrdhApromoters decreased upon transformation of the cells with a plasmid carrying therdh2Rgene, suggesting that Rdh2R acts as repressor, whereas thelacZreporter activity of therdh2Rpromoter was not affected. The transcriptional start sites of bothrdhAgenes in strain CBDB1 and/or the heterologous host mapped to a conserved direct repeat with 11- to 13-bp half-sites. DNase I footprinting revealed binding of Rdh2R to a ∼30-bp sequence covering the complete direct repeat in both promoters, including the transcriptional start sites. Equilibrium sedimentation ultracentrifugation revealed that Rdh2R binds as tetramer to the direct-repeat motif of therdhA(cbdbA1455) promoter. Using electrophoretic mobility shift assays, a similar binding affinity was found for bothrdhApromoters. In the presence of only one half-site of the direct repeat, the interaction was strongly reduced, suggesting a positive cooperativity of binding, for which unusual short palindromes within the direct-repeat half-sites might play an important role.IMPORTANCEDehalococcoides mccartyistrains are obligate anaerobes that grow by organohalide respiration. They have an important bioremediation potential because they are capable of reducing a multitude of halogenated compounds to less toxic products. We are now beginning to understand how these organisms make use of this large catabolic potential, wherebyD. mccartyiexpresses dehalogenases in a compound-specific fashion. MarR-type regulators are often encoded in the vicinity of reductive dehalogenase genes. In this study, we made use of heterologous expression andin vitrostudies to demonstrate that the MarR-type transcription factor Rdh2R acts as a negative regulator. We identify its binding site on the DNA, which suggests a mechanism by which it controls the expression of two adjacent reductive dehalogenase operons.

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