title: Chlorophenol hydroxylase activity encoded by TfdB from 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading Bradyrhizobium sp. strain RD5-C2.
abstract: The tfdB gene encoding chlorophenol hydroxylase and its homolog were found in 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading strain RD5-C2, which belongs to Bradyrhizobium sp. of alpha-Proteobacteria. The nucleotide and deduced amino acid sequence identities of the two genes, designated tfdBa and tfdBb, were 60% and 57% respectively. Their nucleotide sequences most closely matched those of previously reported tfdB, which consisted of those from 2,4-D-degrading beta- and gamma-Proteobacteria and Sphingomonas sp. in alpha-Proteobacteria, with 61-67% identity. The TfdBa expressed in Escherichia coli showed the highest activity for 2,4-dichlorophenol but a narrower range of activity for the other chlorophenols than previously reported TfdBs. In the case of TfdBb, however, no observable activity for any chlorophenols or phenol was detected, although production of a protein with an appropriate molecular size was observed. Based on codon usage patterns and the GC content of the genes, it probable that the tfdBa genes in the 2,4-D-degrading Bradyrhizobium sp. were obtained through horizontal gene transfer.
authors.affiliation: Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane, Japan.
authors.forename: Nguyen L
authors.initials: NL
authors.lastname: Huong
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Itoh
authors.forename: Masao
authors.initials: M
authors.lastname: Miyamoto
authors.forename: Kousuke
authors.initials: K
authors.lastname: Suyama
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamamoto
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism*; D020369:Bradyrhizobium / Q000201:enzymology* / Q000235:genetics; D002733:Chlorophenols / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000235:genetics*; D008969:Molecular Sequence Data
chemical_list: D002733:Chlorophenols; D015084:2,4-Dichlorophenoxyacetic Acid; D006899:Mixed Function Oxygenases