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Dehalogenase

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https://www.readbyqxmd.com/read/28533514/isolation-and-genomic-characterization-of-a-dehalococcoides-strain-suggests-genomic-rearrangement-during-culture
#1
Masafumi Yohda, Kentaro Ikegami, Yuto Aita, Mizuki Kitajima, Ayane Takechi, Megumi Iwamoto, Tomomi Fukuda, Noriyoshi Tamura, Junji Shibasaki, Seiji Koike, Daisuke Komatsu, Sakari Miyagi, Minoru Nishimura, Yoshihito Uchino, Akino Shiroma, Makiko Shimoji, Hinako Tamotsu, Noriko Ashimine, Misuzu Shinzato, Shun Ohki, Kazuma Nakano, Kuniko Teruya, Kazuhito Satou, Takashi Hirano, Osami Yagi
We have developed and characterized a bacterial consortium that reductively dechlorinates trichloroethene to ethene. Quantitative PCR analysis for the 16S rRNA and reductive dehalogenase genes showed that the consortium is highly enriched with Dehalococcoides spp. that have two vinyl chloride reductive dehalogenase genes, bvcA and vcrA, and a trichloroethene reductive dehalogenase gene, tceA. The metagenome analysis of the consortium by the next generation sequencer SOLiD 3 Plus suggests that a Dehalococcoides sp...
May 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28527381/enantioselectivity-of-haloalkane-dehalogenase-linb-on-the-degradation-of-1-2-dichloropropane-a-qm-mm-study
#2
Xiaowen Tang, Ruiming Zhang, Yanwei Li, Qingzhu Zhang, Wenxing Wang
The hydrolysis dechlorination mechanism of a chiral organochlorinepollutant, 1,2-dichloropropane (DCP), catalyzed by haloalkane dehalogenase LinB has been investigated by using a combined quantum mechanics/molecular mechanics method. LinB was confirmed to be enantioselective towards the catabolism of the racemic mixture. Based on the SN2 nucleophilic substitution mechanism, the dechlorination process was identified as the rate-determining step in LinB-catalyzed degradation of 1,2-dichloropropane, the Boltzmann-weighted average potential barrier of which is 18...
May 12, 2017: Bioorganic Chemistry
https://www.readbyqxmd.com/read/28499743/resolution-of-the-uncertainty-in-the-kinetic-mechanism-for-the-trans-3-chloroacrylic-acid-dehalogenase-catalyzed-reaction
#3
Jamison P Huddleston, Susan C Wang, Kenneth A Johnson, Christian P Whitman
trans- and cis-3-Chloroacrylic acid dehalogenase (CaaD and cis-CaaD, respectively) catalyze the hydrolytic dehalogenation of their respective isomers and represent key steps in the bacterial conversion of 1,3-dichloropropene to acetaldehyde. In prior work, a kinetic mechanism for the CaaD-catalyzed reaction could not be unequivocally determined because (1) the order of product release could not be determined and (2) the fluorescence factor for the enzyme species, E*PQ (where P = bromide and Q = malonate semialdehyde, the two products of the reaction) could not be assigned...
May 10, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28424844/microbial-reductive-dehalogenation-of-trihalomethanes-by-a-dehalobacter-containing-co-culture
#4
Siyan Zhao, Matthew J Rogers, Jianzhong He
Trihalomethanes such as chloroform and bromoform, although well-known as a prominent class of disinfection by-products, are ubiquitously distributed in the environment due to widespread industrial usage in the past decades. Chloroform and bromoform are particularly concerning, of high concentrations detected and with long half-lives up to several hundred days in soils and groundwater. In this study, we report a Dehalobacter- and Desulfovibrio-containing co-culture that exhibits dehalogenation of chloroform (~0...
April 19, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28421054/isolation-and-characterization-of-dehalobacter-sp-strain-tecb1-including-identification-of-tcba-a-novel-tetra-and-trichlorobenzene-reductive-dehalogenase
#5
Ricardo Alfán-Guzmán, Haluk Ertan, Mike Manefield, Matthew Lee
Dehalobacter sp. strain TeCB1 was isolated from groundwater near Sydney, Australia, that is polluted with a range of organochlorines. The isolated strain is able to grow by reductive dechlorination of 1,2,4,5-tetrachlorobenzene to 1,3- and 1,4-dichlorobenzene with 1,2,4-trichlorobenzene being the intermediate daughter product. Transient production of 1,2-dichlorobenzene was detected with subsequent conversion to monochlorobenzene. The dehalogenation capability of strain TeCB1 to respire 23 alternative organochlorines was examined and shown to be limited to the use of 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28419658/ancestral-haloalkane-dehalogenases-show-robustness-and-unique-substrate-specificity
#6
Petra Babkova, Eva Sebestova, Jan Brezovsky, Radka Chaloupkova, Jiri Damborsky
Ancestral sequence reconstruction (ASR) represents a powerful approach for empirical testing structure-function relationships of diverse proteins. We employed ASR to predict sequences of five ancestral haloalkane dehalogenases (HLDs) from the HLD-II subfamily. Genes encoding the inferred ancestral sequences were synthesized and expressed in Escherichia coli and the resurrected ancestral enzymes AncHLD1-5 were experimentally characterized. Strikingly, the ancestral HLDs exhibited significantly enhanced thermodynamic stability compared to extant enzymes (ΔTm up to 24 °C)...
April 17, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28411224/concurrent-haloalkanoate-degradation-and-chlorate-reduction-by-pseudomonas-chloritidismutans-aw-1-t
#7
Peng Peng, Ying Zheng, Jasper J Koehorst, Peter J Schaap, Alfons J M Stams, Hauke Smidt, Siavash Atashgahi
Haloalkanoates are environmental pollutants that can be degraded aerobically by microorganisms producing hydrolytic dehalogenases. However, there is lack of information about anaerobic degradation of haloalkanoates. Genome analysis of Pseudomonas chloritidismutans AW-1(T), a facultative anaerobic chlorate-reducing bacterium, showed presence of two putative haloacid dehalogenase genes, l-dex and dehI, encoding an L-2-haloacid dehalogenase (L-DEX) and a halocarboxylic acid dehydrogenase (DehI). Hence, we studied concurrent degradation of haloalkanoates and chlorate as a yet unexplored trait of strain AW-1(T) The deduced amino acid sequences of L-DEX and DehI revealed 33-37% and 26-86% identities with biochemically/structurally characterized L-DEX and D-, DL-2-haloacid dehalogenase enzymes, respectively...
April 14, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28397170/the-organohalide-respiring-bacterium-sulfurospirillum-multivorans-a-natural-source-for-unusual-cobamides
#8
REVIEW
Torsten Schubert
Cobamides ('complete' corrinoids) are essential for organohalide-respiring bacteria because they act as cofactors of reductive dehalogenases (RDases). RDases are the key enzymes in organohalide respiration, a process relevant for environmental remediation. More than a decade ago, the unusual norpseudo-B12 was identified as cofactor of the tetrachloroethene RDase (PceA) purified from the epsilonproteobacterium Sulfurospirillum multivorans. Since then, the question was raised whether or not the production of the uncommon cobamide is a specific adaptation to the requirements of PceA...
May 2017: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28381628/a-puzzling-homology-a-brittle-star-using-a-putative-cnidarian-type-luciferase-for-bioluminescence
#9
Jérôme Delroisse, Esther Ullrich-Lüter, Stefanie Blaue, Olga Ortega-Martinez, Igor Eeckhaut, Patrick Flammang, Jérôme Mallefet
Bioluminescence relies on the oxidation of a luciferin substrate catalysed by a luciferase enzyme. Luciferins and luciferases are generic terms used to describe a large variety of substrates and enzymes. Whereas luciferins can be shared by phylogenetically distant organisms which feed on organisms producing them, luciferases have been thought to be lineage-specific enzymes. Numerous light emission systems would then have co-emerged independently along the tree of life resulting in a plethora of non-homologous luciferases...
April 2017: Open Biology
https://www.readbyqxmd.com/read/28359974/purifying-cloning-and-characterizing-a-novel-dehalogenase-from-bacillus-sp-gzt-to-enhance-the-biodegradation-of-2-4-6-tribromophenol-in-water
#10
Zhishu Liang, Guiying Li, Taicheng An
2,4,6-Tribromophenol (TBP), an intermediate of brominated flame retardants, can easily release to environment and recalcitrant to degradation. Previously, Bacillus sp. GZT, a pure aerobic strain capable of simultaneously debrominating and mineralizing TBP, was successfully isolated by us. To further obtain a practical application and dig up its TBP degradation mechanism, a total of 46.7-fold purification of a novel dehalogenase with a final specific activity of 18.9 U mg(-1) and a molecular mass of 63.4 kDa was achieved...
March 27, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28351914/the-n-acetylmuramic-acid-6-phosphate-phosphatase-mupp-completes-the-pseudomonas-peptidoglycan-recycling-pathway-leading-to-intrinsic-fosfomycin-resistance
#11
Marina Borisova, Jonathan Gisin, Christoph Mayer
Bacterial cells are encased in and stabilized by a netlike peptidoglycan (PGN) cell wall that undergoes turnover during bacterial growth. PGN turnover fragments are frequently salvaged by the cells via a pathway referred to as PGN recycling. Two different routes for the recycling of the cell wall sugar N-acetylmuramic acid (MurNAc) have been recognized in bacteria. In Escherichia coli and related enterobacteria, as well as in most Gram-positive bacteria, MurNAc is recovered via a catabolic route requiring a MurNAc 6-phosphate etherase (MurQ in E...
March 28, 2017: MBio
https://www.readbyqxmd.com/read/28334478/different-structural-origins-of-the-enantioselectivity-of-haloalkane-dehalogenases-toward-linear-%C3%AE-haloalkanes-open-solvated-versus-occluded-desolvated-active-sites
#12
Veronika Liskova, Veronika Stepankova, David Bednar, Jan Brezovsky, Zbynek Prokop, Radka Chaloupkova, Jiri Damborsky
The enzymatic enantiodiscrimination of linear β-haloalkanes is difficult because the simple structures of the substrates prevent directional interactions. Herein we describe two distinct molecular mechanisms for the enantiodiscrimination of the β-haloalkane 2-bromopentane by haloalkane dehalogenases. Highly enantioselective DbjA has an open, solvent-accessible active site, whereas the engineered enzyme DhaA31 has an occluded and less solvated cavity but shows similar enantioselectivity. The enantioselectivity of DhaA31 arises from steric hindrance imposed by two specific substitutions rather than hydration as in DbjA...
March 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28282255/effect-of-zn-2-on-halohydrin-dehalogenase-expression-and-accumulation-through-multi-parameter-correlation-research-with-escherichia-coli-p84a-mc1061
#13
Xiao Li, Yu-Di Luo, Dong-Rui Pan, Xiao-Dan Shi, Ya-Li Tan, Zhi-Hong Li
Using 5 Zn(2+) supplementation strategies in a 50 L batch bioreactor named FUS-50L(A), possible correlations among Zn(2+) content and addition timing, physiologic activity (PA), halohydrin dehalogenase (HheC) accumulation of Escherichia coli P84A/MC1061 were systematically investigated. First, Zn(2+) was confirmed as the significant factor, and its optimal concentration for HheC expression was 3.87 mg/L through fermentation experiments in shaking flasks. Second, based on experimental results from the different strategies, it was found that PA, nutrient consumption rate (NCR) and specific growth rate (μ) for E...
March 10, 2017: Bioengineered
https://www.readbyqxmd.com/read/28265269/marine-derived-biocatalysts-importance-accessing-and-application-in-aromatic-pollutant-bioremediation
#14
REVIEW
Efstratios Nikolaivits, Maria Dimarogona, Nikolas Fokialakis, Evangelos Topakas
The aim of the present review is to highlight the potential use of marine biocatalysts (whole cells or enzymes) as an alternative bioprocess for the degradation of aromatic pollutants. Firstly, information about the characteristics of the still underexplored marine environment and the available scientific tools used to access novel marine-derived biocatalysts is provided. Marine-derived enzymes, such as dioxygenases and dehalogenases, and the involved catalytic mechanisms for the degradation of aromatic and halogenated compounds, are presented, with the purpose of underpinning their potential use in bioremediation...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28251763/a-13-week-research-based-biochemistry-laboratory-curriculum
#15
Scott T Lefurgy, Emily C Mundorff
Here, we present a 13-week research-based biochemistry laboratory curriculum designed to provide the students with the experience of engaging in original research while introducing foundational biochemistry laboratory techniques. The laboratory experience has been developed around the directed evolution of an enzyme chosen by the instructor, with mutations designed by the students. Ideal enzymes for this curriculum are able to be structurally modeled, solubly expressed, and monitored for activity by UV/Vis spectroscopy, and an example curriculum for haloalkane dehalogenase is given...
March 2, 2017: Biochemistry and Molecular Biology Education
https://www.readbyqxmd.com/read/28238079/development-and-application-of-a-rapid-user-friendly-and-inexpensive-method-to-detect-dehalococcoides-sp-reductive-dehalogenase-genes-from-groundwater
#16
Yogendra H Kanitkar, Robert D Stedtfeld, Paul B Hatzinger, Syed A Hashsham, Alison M Cupples
TaqMan probe-based quantitative polymerase chain reaction (qPCR) specific to the biomarker reductive dehalogenase (RDase) genes is a widely accepted molecular biological tool (MBT) for determining the abundance of Dehalococcoides sp. in groundwater samples from chlorinated solvent-contaminated sites. However, there are significant costs associated with this MBT. In this study, we describe an approach that requires only low-cost laboratory equipment (a bench top centrifuge and a water bath) and requires less time and resources compared to qPCR...
February 25, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28191945/engineered-surface-immobilized-enzyme-that-retains-high-levels-of-catalytic-activity-in-air
#17
Somayesadat Badieyan, Qiuming Wang, Xingquan Zou, Yaoxin Li, Maggie Herron, Nicholas L Abbott, Zhan Chen, E Neil G Marsh
In the absence of aqueous buffer, most enzymes retain little or no activity; however, "water-free" enzymes would have many diverse applications. Here, we describe the chemically precise immobilization of an enzyme on an engineered surface designed to support catalytic activity in air at ambient humidity. Covalent immobilization of haloalkane dehalogenase on a surface support displaying poly(sorbitol methacrylate) chains resulted in ∼40-fold increase in activity over lyophilized enzyme powders for the gas-phase dehalogenation of 1-bromopropane...
February 16, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28191552/a-common-mechanism-for-coenzyme-cobalamin-dependent-reductive-dehalogenases
#18
Linus O Johannissen, David Leys, Sam Hay
Distinct mechanisms have been proposed for the biological dehalogenation catalyzed by cobalamin-dependent enzymes, with two recent crystallographic studies suggesting different mechanisms based on the observed interaction between the organohalide substrate and cobalamin. In one case, involving an aromatic dibromide substrate in NpRdhA, a novel Co(II)-Br interaction was observed using EPR, suggesting a mechanism involving a [CoXR] adduct. However, in the case of trichloroethylene in PceA, a significantly longer Co-Cl distance was observed in X-ray crystal structures, suggesting a dissociative electron transfer mechanism...
February 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28165015/enhancing-the-biocatalytic-manufacture-of-the-key-intermediate-of-atorvastatin-by-focused-directed-evolution-of-halohydrin-dehalogenase
#19
Yu Luo, Yangzi Chen, Hongmin Ma, ZhenHua Tian, Yeqi Zhang, Jian Zhang
Halohydrin dehalogenases (HHDHs) are biocatalytically interesting enzymes due to their ability to form C-C, C-N, C-O, and C-S bonds. One of most important application of HHDH was the protein engineering of HheC (halohydrin dehalogenase from Agrobacterium radiobacter AD1) for the industrial manufacturing of ethyl (R)-4-cyano-3-hydroxybutanoate (HN), a key chiral synthon of a cholesterol-lowering drug of atorvastatin. During our development of an alternative, more efficient and economic route for chemo-enzymatic preparation of the intermediate of atorvastatin, we found that the HheC2360 previously reported for HN manufacture, had insufficient activity for the cyanolysis production of tert-butyl (3 R,5 S)-6-cyano-3,5-dihydroxyhexanoate (A7)...
February 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28104837/the-role-of-dimer-asymmetry-and-protomer-dynamics-in-enzyme-catalysis
#20
Tae Hun Kim, Pedram Mehrabi, Zhong Ren, Adnan Sljoka, Christopher Ing, Alexandr Bezginov, Libin Ye, Régis Pomès, R Scott Prosser, Emil F Pai
Freeze-trapping x-ray crystallography, nuclear magnetic resonance, and computational techniques reveal the distribution of states and their interconversion rates along the reaction pathway of a bacterial homodimeric enzyme, fluoroacetate dehalogenase (FAcD). The crystal structure of apo-FAcD exhibits asymmetry around the dimer interface and cap domain, priming one protomer for substrate binding. This asymmetry is dynamically averaged through conformational exchange on a millisecond time scale. During catalysis, the protomer conformational exchange rate becomes enhanced, the empty protomer exhibits increased local disorder, and water egresses...
January 20, 2017: Science
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