Co-Authors:
Chen, K., Department of Microbiology, Ministry of Agriculture, Key Laboratory of Microbiological Engineering of Agricultural Environment, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
Xu, X., Department of Microbiology, Ministry of Agriculture, Key Laboratory of Microbiological Engineering of Agricultural Environment, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
Zhang, L., Department of Microbiology, Ministry of Agriculture, Key Laboratory of Microbiological Engineering of Agricultural Environment, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
Gou, Z., Department of Microbiology, Ministry of Agriculture, Key Laboratory of Microbiological Engineering of Agricultural Environment, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
Li, S., Department of Microbiology, Ministry of Agriculture, Key Laboratory of Microbiological Engineering of Agricultural Environment, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
Freilich, S., Institute of Plant Sciences, Newe-Ya'ar Research Center, Agricultural Research Organization, Ramat Yishay, Israel
Jiang, J., Department of Microbiology, Ministry of Agriculture, Key Laboratory of Microbiological Engineering of Agricultural Environment, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
Abstract:
Comamonas plasmids play important roles in shaping the phenotypes of their hosts and the adaptation of these hosts to changing environments, and understanding the evolutionary strategy of these plasmids is thus of great concern. In this study, the sequence of the 119-kb 3,5-dibromo-4-hydroxybenzonitrile-catabolizing plasmid pBHB from Comamonas sp. strain 7D-2 was studied and compared with those of three other Comamonas haloaromatic catabolic plasmids. Incompatibility group determination based on a phylogenetic analysis of 24 backbone gene proteins, as well as TrfA, revealed that these four plasmids all belong to the IncP-1β subgroup. Comparison of the four plasmids revealed a conserved backbone region and diverse genetic-load regions. The four plasmids share a core genome consisting of 40 genes (> 50% similarities) and contain 12 to 50 unique genes each, most of which are xenobiotic-catabolic genes. Two functional reductive dehalogenase gene clusters are specifically located on pBHB, showing distinctive evolution of pBHB for haloaromatics. The higher catabolic ability of the bhbA2B2 cluster than the bhbAB cluster may be due to the transcription levels and the character of the dehalogenase gene itself rather than that of its extracytoplasmic binding receptor gene. The plasmid pBHB is riddled with transposons and insertion sequence (IS) elements, and ISs play important roles in the evolution of pBHB. The analysis of the origin of the bhb genes on pBHB suggested that these accessory genes evolved independently. Our work provides insights into the evolutionary strategies of Comamonas plasmids, especially into the adaptation mechanism employed by pBHB for haloaromatics. © 2016, American Society for Microbiology. All Rights Reserved.