title: Two rhizobial strains, Mesorhizobium loti MAFF303099 and Bradyrhizobium japonicum USDA110, encode haloalkane dehalogenases with novel structures and substrate specificities.
abstract: Haloalkane dehalogenases are key enzymes for the degradation of halogenated aliphatic pollutants. Two rhizobial strains, Mesorhizobium loti MAFF303099 and Bradyrhizobium japonicum USDA110, have open reading frames (ORFs), mlr5434 and blr1087, respectively, that encode putative haloalkane dehalogenase homologues. The crude extracts of Escherichia coli strains expressing mlr5434 and blr1087 showed the ability to dehalogenate 18 halogenated compounds, indicating that these ORFs indeed encode haloalkane dehalogenases. Therefore, these ORFs were referred to as dmlA (dehalogenase from Mesorhizobium loti) and dbjA (dehalogenase from Bradyrhizobium japonicum), respectively. The principal component analysis of the substrate specificities of various haloalkane dehalogenases clearly showed that DbjA and DmlA constitute a novel substrate specificity class with extraordinarily high activity towards beta-methylated compounds. Comparison of the circular dichroism spectra of DbjA and other dehalogenases strongly suggested that DbjA contains more alpha-helices than the other dehalogenases. The dehalogenase activity of resting cells and Northern blot analyses both revealed that the dmlA and dbjA genes were expressed under normal culture conditions in MAFF303099 and USDA110 strain cells, respectively.
authors.affiliation: Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Sato
authors.forename: Marta
authors.initials: M
authors.lastname: Monincová
authors.forename: Radka
authors.initials: R
authors.lastname: Chaloupková
authors.forename: Zbynek
authors.initials: Z
authors.lastname: Prokop
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ohtsubo
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Minamisawa
authors.forename: Masataka
authors.initials: M
authors.lastname: Tsuda
authors.forename: Jirí
authors.initials: J
authors.lastname: Damborsky
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nagata
mesh_terms: D020561:Alphaproteobacteria / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D000595:Amino Acid Sequence; D020369:Bradyrhizobium / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D002942:Circular Dichroism; D003001:Cloning, Molecular; D003470:Culture Media; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006867:Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D015999:Multivariate Analysis; D016297:Mutagenesis, Site-Directed; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D003470:Culture Media; D006867:Hydrolases; C046137:haloalkane dehalogenase