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. 2007 Apr 16;51(6):2260–2264. doi: 10.1128/AAC.00242-07

FIG. 2.

FIG. 2.

Genetic structure of pB1000. (A) Comparison of the genetic structures of pB1000, pHS-Tet, and pAB2. pB1000 contains the transcriptional terminator and a conserved direct repeat (white box) from pHS-Tet (13). Analogously, the transcriptional terminator of blaROB-1 is present in pHS-Tet. These data indicate that pB1000 and pHS-Tet might have evolved from a common ancestor bearing together the tet(B) and blaROB-1 genes. pAB2 has an inverted copy of blaROB-1. The empty triangle indicates the position of the GACTT sequence. (B) Potential recombination sites of blaROB-1. pHS-Tet has a single copy of the GACTT sequence. Further, in pB1000 and pAB2, blaROB-1 is embedded between the GACTT repeated sequences, indicating strongly that these sequences mediate mobilization of blaROB-1 via an intermediary hairpin structure and duplication of the insertion site.