title: Properties and biotechnological applications of natural and engineered haloalkane dehalogenases.
abstract: Haloalkane dehalogenases (HLDs) convert halogenated compounds to corresponding alcohols, halides, and protons. They belong to α/β-hydrolases, and their principal catalytic mechanism is SN2 nucleophilic substitution followed by the addition of water. Since HLDs generally have broad and different substrate specificities, they have various biotechnological applications. HLDs have previously been believed to be present only in bacterial strains that utilize xenobiotic halogenated compounds, and three archetypal HLDs, i.e., DhlA, DhaA, and LinB, have been intensively investigated by biochemical, structural, and computational analyses. Furthermore, by using the resulting data and target-selected random mutagenesis approaches, these HLDs have been successfully engineered to improve their substrate specificities and activities. In addition, important insights into protein evolution have been obtained by studying these HLDs. At the same time, the genome and metagenome information has revealed that HLD homologues are widely distributed in many bacterial strains, including ones that have not been reported to degrade halogenated compounds. Some of these cryptic HLD homologues have been experimentally confirmed to be "true" HLDs with unique substrate specificities and enantioselectivities. Although their biological functions and physiological roles remain mysterious, these potential HLDs are considered promising materials for the development of new biocatalysts.
authors.affiliation: Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai, 980-8577, Japan. aynaga@ige.tohoku.ac.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nagata
authors.affiliation: Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai, 980-8577, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ohtsubo
authors.affiliation: Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai, 980-8577, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Tsuda
mesh_terms: D001709:Biotechnology / Q000379:methods*; D006867:Hydrolases / Q000235:genetics* / Q000378:metabolism*; D015202:Protein Engineering / Q000379:methods; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D011994:Recombinant Proteins; D006867:Hydrolases; C046137:haloalkane dehalogenase
keywords: Bacterial genome; Environmental pollutant; Haloalkane dehalogenase; Halogenated compound; Hydrolase; Protein engineering; Protein evolution