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

作者：Tabata Michiro; Ohhata Satoshi; Nikawadori Yuki; Kishida Kouhei; Sato Takuya; Kawasumi Toru; Kato Hiromi; Ohtsubo Yoshiyuki; Tsuda Masataka; Nagata Yuji^*

来源：DNA Research, 2016, 23(6): 581-599.

DOI：10.1093/dnares/dsw041

• xenobiotics
• evolution
• sphingomonads
• genome
• mobile genetic elements

gamma-Hexachlorocyclohexane (gamma-HCH) is a recalcitrant man-made chlorinated pesticide. Here, the complete genome sequences of four gamma-HCH-degrading sphingomonad strains, which are most unlikely to have been derived from one ancestral gamma-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 gamma-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 gamma-HCH utilization exhibit structural divergence, which reflects the phylogenetic relationship of their hosts. Replicon organization and location of the lin genes in the four genomes are significantly different with one another, and that most of the specific lin genes are located on multiple sphingomonad-unique plasmids. Copies of IS6100, the most abundant insertion sequence in the four strains, are often located in close proximity to the specific lin genes. Analysis of the footprints of target duplication upon IS6100 transposition and the experimental detection of IS6100 transposition strongly suggested that the IS6100 transposition has caused dynamic genome rearrangements and the diversification of lin-flanking regions in the four strains.

• 出版日期2016-12