Comparison of the complete genome sequences of four γ-hexachlorocyclohexane-degrading bacterial strains: insights into the evolution of bacteria able to degrade a recalcitrant man-made pesticide.

γ-Hexachlorocyclohexane (γ-HCH) is a recalcitrant man-made chlorinated pesticide. Here, the complete genome sequences of four γ-HCH-degrading sphingomonad strains, which are most unlikely to have been derived from one ancestral γ-HCH degrader, were compared. Together with several experimental data, we showed that (i) all the four strains carry almost identical linA to linE genes for the conversion of γ-HCH to maleylacetate (designated "specific" lin genes), (ii) considerably different genes are used for the metabolism of maleylacetate in one of the four strains, and (iii) the linKLMN genes for the putative ABC transporter necessary for γ-HCH utilization exhibit structural divergence, which reflects the phylogenetic relationship of their hosts.

Complete Genome Sequence of a γ-Hexachlorocyclohexane Degrader, Sphingobium sp. Strain TKS, Isolated from a γ-Hexachlorocyclohexane-Degrading Microbial Community.

Here, we report the complete genome sequence of a γ-hexachlorocyclohexane (γ-HCH) degrader,Sphingobiumsp. strain TKS, which was isolated from a γ-HCH-degrading microbial community. The genome of TKS consists of two chromosomes and nine plasmids.

Complete Genome Sequence of a γ-Hexachlorocyclohexane-Degrading Bacterium, Sphingobium sp. Strain MI1205.

Here, we report the complete genome sequence of a γ-hexachlorocyclohexane (γ-HCH)-degrading bacterium,Sphingobiumsp. strain MI1205. The genome of MI1205 consists of two chromosomes and four plasmids with sizes of 33 to 292 kb.

Stepwise enhancement of catalytic performance of haloalkane dehalogenase LinB towards β-hexachlorocyclohexane.

Two haloalkane dehalogenases, LinBUT and LinBMI, each with 296 amino acid residues, exhibit only seven amino acid residue differences between them, but LinBMI's catalytic performance towards β-hexachlorocyclohexane (β-HCH) is considerably higher than LinBUT's. To elucidate the molecular basis governing this difference, intermediate mutants between LinBUT and LinBMI were constructed and kinetically characterized. The activities of LinBUT-based mutants gradually increased by cumulative mutations into LinBUT, and the effects of the individual amino acid substitutions depended on combination with other mutations.