Haloalkane dehalogenases (HLDs) are \uffce\uffb1/\uffce\uffb2\uffe2\uff80\uff90hydrolases that convert halogenated compounds to their corresponding alcohols. The overall kinetic mechanism proceeds via four steps: (i) binding of halogenated substrate, (ii) bimolecular nucleophilic substitution (SN2) leading to the cleavage of a carbon\uffe2\uff80\uff90halogen bond and the formation of an alkyl\uffe2\uff80\uff90enzyme intermediate, (iii) nucleophilic addition of a water molecule resulting in the hydrolysis of the intermediate to the corresponding alcohol and (iv) release of the reaction products \uffe2\uff80\uff93 an alcohol, a halide ion and a proton. Although, the overall reaction has been reported as irreversible, several kinetic evidences from previous studies suggest the reversibility of the first SN2 chemical step. To study this phenomenon, we have engineered HLDs to stop the catalytic cycle at the stage of the alkyl\uffe2\uff80\uff90enzyme intermediate. The ability of the intermediate to exchange halides was confirmed by a stopped\uffe2\uff80\uff90flow fluorescence binding analysis. Finally, the transhalogenation reaction was confirmed with several HLDs and 2,3\uffe2\uff80\uff90dichloropropene in the presence of a high concentration of iodide. The formation of the transhalogenation product 3\uffe2\uff80\uff90iodo\uffe2\uff80\uff902\uffe2\uff80\uff90chloropropene catalysed by five mutant HLDs was identified by gas chromatography coupled with mass spectrometry. Hereby we demonstrated the reversibility of the cleavage of the carbon\uffe2\uff80\uff90halogen bond by HLDs resulting in a transhalogenation. After optimization, the transhalogenation reaction can possibly find its use in biocatalytic applications. Enabling this reaction by strategically engineering the enzyme to stop at an intermediate in the catalytic cycle that is synthetically more useful than the product of the natural pathway is a novel concept.
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", "keywords": ["0301 basic medicine", "enzyme catalysis; halide exchange; haloalkane dehalogenase; nucleophilic substitution; redirection of reaction; transhalogenation", "0303 health sciences", "03 medical and health sciences"]}, "links": [{"href": "https://onlinelibrary.wiley.com/doi/pdf/10.1002/adsc.201900132"}, {"href": "https://doi.org/10.1002/adsc.201900132"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Advanced%20Synthesis%20%26amp%3B%20Catalysis", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1002/adsc.201900132", "name": "item", "description": "10.1002/adsc.201900132", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1002/adsc.201900132"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2019-04-17T00:00:00Z"}}, {"id": "10.1002/cbic.202000051", "type": "Feature", "geometry": null, "properties": {"updated": "2026-04-13T16:14:06Z", "type": "Journal Article", "created": "2020-01-31", "title": "An Engineered E.\u2005coli Strain for Direct in Vivo Fluorination", "description": "AbstractSelectively fluorinated compounds are found frequently in pharmaceutical and agrochemical products where currently 25\uffe2\uff80\uff9330\uffe2\uff80\uff89% of optimised compounds emerge from development containing at least one fluorine atom. There are many methods for the site\uffe2\uff80\uff90specific introduction of fluorine, but all are chemical and they often use environmentally challenging reagents. Biochemical processes for C\uffe2\uff88\uff92F bond formation are attractive, but they are extremely rare. In this work, the fluorinase enzyme, originally identified from the actinomycete bacterium Streptomyces cattleya, is engineered into Escherichia coli in such a manner that the organism is able to produce 5\uffe2\uff80\uffb2\uffe2\uff80\uff90fluorodeoxyadenosine (5\uffe2\uff80\uffb2\uffe2\uff80\uff90FDA) from S\uffe2\uff80\uff90adenosyl\uffe2\uff80\uff90l\uffe2\uff80\uff90methionine (SAM) and fluoride in live E.\uffe2\uff80\uff85coli cells. Success required the introduction of a SAM transporter and deletion of the endogenous fluoride efflux capacity in order to generate an E.\uffe2\uff80\uff85coli host that has the potential for future engineering of more elaborate fluorometabolites.
", "keywords": ["SAM transporters", "0301 basic medicine", "570", "S-Adenosylmethionine", "0303 health sciences", "Deoxyadenosines", "Halogenation", "DAS", "Fluorine", "Halogenations", "540", "QD Chemistry", "Streptomyces", "3. Good health", "03 medical and health sciences", "Bacterial Proteins", "Isomerism", "Escherichia coli", "QD", "Fluoride channels", "Genetic Engineering", "Oxidoreductases", "Fluorinases"]}, "links": [{"href": "https://onlinelibrary.wiley.com/doi/pdf/10.1002/cbic.202000051"}, {"href": "https://doi.org/10.1002/cbic.202000051"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/ChemBioChem", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1002/cbic.202000051", "name": "item", "description": "10.1002/cbic.202000051", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1002/cbic.202000051"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2020-03-03T00:00:00Z"}}, {"id": "10.1016/j.copbio.2021.11.009", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-04-13T16:16:07Z", "type": "Journal Article", "created": "2021-12-23", "title": "Synthetic metabolism for biohalogenation", "description": "The pressing need for novel bioproduction approaches faces a limitation in the number and type of molecules accessed through synthetic biology. Halogenation is widely used for tuning physicochemical properties of molecules and polymers, but traditional halogenation chemistry often lacks specificity and generates harmful by-products. Here, we pose that deploying synthetic metabolism tailored for biohalogenation represents an unique opportunity towards economically attractive and environmentally friendly organohalide production. On this background, we discuss growth-coupled selection of functional metabolic modules that harness the rich repertoire of biosynthetic and biodegradation capabilities of environmental bacteria for in vivo biohalogenation. By rationally combining these approaches, the chemical landscape of living cells can accommodate bioproduction of added-value organohalides which, as of today, are obtained by traditional chemistry.", "keywords": ["0301 basic medicine", "0303 health sciences", "03 medical and health sciences", "Biodegradation", " Environmental", "Bacteria", "Halogenation", "Synthetic Biology"]}, "links": [{"href": "https://doi.org/10.1016/j.copbio.2021.11.009"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Current%20Opinion%20in%20Biotechnology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.copbio.2021.11.009", "name": "item", "description": "10.1016/j.copbio.2021.11.009", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.copbio.2021.11.009"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-04-01T00:00:00Z"}}, {"id": "10.1016/j.watres.2019.06.068", "type": "Feature", "geometry": null, "properties": {"license": "Closed Access", "updated": "2026-04-13T16:17:43Z", "type": "Journal Article", "created": "2019-06-27", "title": "Accelerated microbial reductive dechlorination of 2,4,6-trichlorophenol by weak electrical stimulation", "description": "Microbial reductive dechlorination of chlorinated aromatics frequently suffers from the long dechlorination period and the generation of toxic metabolites. Biocathode bioelectrochemical systems were verified to be effective in the degradation of various refractory pollutants. However, the electrochemical and microbial related working mechanisms for bio-dechlorination by electro-stimulation remain poorly understood. In this study, we reported the significantly improved 2,4,6-trichlorophenol dechlorination activity through the weak electro-stimulation (cathode potential of\u00a0-0.36\u202fV vs. SHE), as evidenced by the 3.1 times higher dechlorination rate and the complete dechlorination ability with phenol as the end dechlorination product. The high reductive dechlorination rate (20.8\u202f\u03bcM/d) could be maintained by utilizing electrode as an effective electron donor (coulombic efficiency of 82.3\u202f\u00b1\u202f4.8%). Cyclic voltammetry analysis of the cathodic biofilm gave the direct evidences of the cathodic respiration with the improved and positive-shifted reduction peaks of 2,4,6-TCP, 2,4-DCP and 4-CP. The optimal 2,4,6-TCP reductive dechlorination rate (24.2\u202f\u03bcM/d) was obtained when a small amount of lactate (2\u202fmM) was added, and the generation of H2 and CH4 were accompanied due to the biological fermentation and methanogenesis. The electrical stimulation significantly altered the cathodic biofilm structure and composition with some potential dechlorinators (like Acetobacterium) predominated. The microbial interactions in the ecological network of cathodic biofilm were more simplified than the planktonic community. However, some potential dechlorinators (Acetobacterium, Desulfovibrio, etc.) shared more positive interactions. The co-existence and possible cooperative relationships between potential dechlorinators and fermenters (Sedimentibacter, etc.) were revealed. Meanwhile, the competitive interrelations between potential dechlorinators and methanogens (Methanomassiliicoccus) were found. In the network of plankton, the fermenters and methanogens possessed the more positive interrelations. Electro-stimulation at the cathodic potential of\u00a0-0.36\u202fV selectively enhanced the dechlorination function, while it showed little influence on either fermentation or methanogenesis process. The study gave suggestions for the enhanced bioremediation of chlorinated aromatics, in views of the electro-stimulation capacity, efficiency and microbial interrelations related microbial mechanism.", "keywords": ["Biodegradation", " Environmental", "Halogenation", "0211 other engineering and technologies", "02 engineering and technology", "01 natural sciences", "Electric Stimulation", "Chlorophenols", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.watres.2019.06.068"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Water%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.watres.2019.06.068", "name": "item", "description": "10.1016/j.watres.2019.06.068", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.watres.2019.06.068"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2019-10-01T00:00:00Z"}}, {"id": "10.1021/acs.est.0c01565", "type": "Feature", "geometry": null, "properties": {"updated": "2026-04-13T16:17:49Z", "type": "Journal Article", "created": "2020-05-15", "title": "Changes in Antibiotic Resistance Gene Levels in Soil after Irrigation with Treated Wastewater: A Comparison between Heterogeneous Photocatalysis and Chlorination", "description": "Wastewater (WW) reuse is expected to be increasingly indispensable in future water management to mitigate water scarcity. However, this increases the risk of antibiotic resistance (AR) dissemination via irrigation. Herein, a conventional (chlorination) and an advanced oxidation process (heterogeneous photocatalysis (HPC)) were used to disinfect urban WW to the same target of Escherichia coli <10 CFU/100 mL and used to irrigate lettuce plants (Lactuca sativa) set up in four groups, each receiving one of four water types, secondary WW (positive control), fresh water (negative control), chlorinated WW, and HPC WW. Four genes were monitored in water and soil, 16S rRNA as an indicator of total bacterial load, intI1 as a gene commonly associated with anthropogenic activity and AR, and two AR genes blaOXA-10 and qnrS. Irrigation with secondary WW resulted in higher dry soil levels of intI1 (from 1.4 \u00d7 104 copies/g before irrigation to 3.3 \u00d7 105 copies/g after). HPC-treated wastewater showed higher copy numbers of intI1 in the irrigated soil than chlorination, but the opposite was true for blaOXA-10. The results indicate that the current treatment is insufficient to prevent dissemination of AR markers and that HPC does not offer a clear advantage over chlorination.", "keywords": ["Agricultural Irrigation", "Halogenation", "0211 other engineering and technologies", "Drug Resistance", " Microbial", "02 engineering and technology", "Wastewater", "Waste Disposal", " Fluid", "01 natural sciences", "6. Clean water", "3. Good health", "Soil", "antibiotic resistance; wastewater reuse; photocatalysis; wastewater irrigation", "RNA", " Ribosomal", " 16S", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://www.iris.unisa.it/bitstream/11386/4749040/1/es-2020-01565f.R1_Proof_hi.pdf"}, {"href": "https://pubs.acs.org/doi/pdf/10.1021/acs.est.0c01565"}, {"href": "https://doi.org/10.1021/acs.est.0c01565"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Environmental%20Science%20%26amp%3B%20Technology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1021/acs.est.0c01565", "name": "item", "description": "10.1021/acs.est.0c01565", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1021/acs.est.0c01565"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2020-05-15T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Halogenation&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Halogenation&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Halogenation&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Halogenation&offset=6", "hreflang": "en-US"}], "numberMatched": 6, "numberReturned": 6, "distributedFeatures": [], "timeStamp": "2026-04-15T00:10:39.623255Z"}