Sequence of plasmid pBS228 and reconstruction of the IncCP-1α phylogeny

The antibiotic resistance plasmid pBS228 has been completely sequenced, and revealed to be descended from a plasmid virtually identical to the Birmingham IncP-la plasmid RK2/RP4/RP1. However, it has three additional transposon insertions, one of which is responsible for the extra antibiotic resistances conferred. Loss of kanamycin resistance, which is characteristic of most IncP-1 alpha plasmids, is the result of this insertion. A second transposon causes inactivation of the mating pair formation apparatus, rendering the plasmid non-self-transmissible. Comparison with the published data for other IncP-la plasmids gives insight into the recent evolutionary history of this group as well as the acquisition and transmission of one of the first ampicillin resistance transposons discovered. (c) 2007 Elsevier Inc. All rights reserved.