The IncP-1 plasmid backbone adapts to different host bacterial species and evolves through homologous recombination.
Bottom Line: We also found that homologous recombination is a prominent feature of the plasmid backbone evolution.Analysis of genomic signatures indicates that the plasmids have adapted to different host bacterial species.Globally circulating IncP-1 plasmids hence contain mosaic structures of segments derived from several parental plasmids that have evolved in, and adapted to, different, phylogenetically very distant host bacterial species.
Affiliation: Department of Cell and Molecular Biology, Microbiology, University of Gothenburg, Box 462, SE 413 46, Gothenburg, Sweden. email@example.comShow MeSH
Mentions: The genetic distance between the amino-acid (AA) sequence of each backbone gene in pMCBF1 and their corresponding genes in the 23 previously described IncP-1 plasmids was estimated by a maximum likelihood approach. The backbone gene content in the 25 plasmids differs significantly and only 24 homologues of the 41 backbone genes in pMCBF1 were present in all analysed plasmids (Fig. 1). The AA similarity differed also widely with trbD being the most conserved gene. Among all 23 plasmids, plasmid pB4 presents the closest genetic distance to pMCBF1 in genes trbK, trbL, traG and traO, whereas pB4 genes traC2 and traK present the longest genetic distance. Similarly, the pKJK5 genes trbB, trbE, trbJ, traH, traJ, klcB and klcA presented the closest, and the two genes upf30.5 and kleB in the same plasmid presented the longest genetic distance to pMCBF1. Only plasmids pAKD4 and pQKH54 did not have any gene with the closest genetic distance to pMCBF1. Such alterations of relative genetic distances may be explained either by unequal nucleotide substitution rates or by an evolutionary history including homologous recombination (that is, the fact that the different genes in each plasmid backbone have different ancestries).
Affiliation: Department of Cell and Molecular Biology, Microbiology, University of Gothenburg, Box 462, SE 413 46, Gothenburg, Sweden. firstname.lastname@example.org