FIG. 1.

Physical and genetic map of the multidrug resistance plasmid pSK156. The locations of genes involved in the following functions are represented: penicillin resistance (blaZ), multidrug resistance (qacR and qacB), and site-specific recombination (sin). Restriction sites are abbreviated as follows: B (BglII), E (EcoRI), Ps (PstI), P (PvuII), and S (SalI); only selected EcoRI sites are displayed. Beneath the pSK156 map is a diagrammatic comparison of the sequenced regions of pSK156 and pSK23 with the homologous regions of pSK1; a kilobase scale is indicated. Using a series of synthetic oligonucleotides, the nucleotide sequences of pSK23 and pSK156 were determined on both strands. The nucleotide sequence of pSK1 was determined previously (3, 15, 17). The shaded regions represent areas with high degrees of sequence similarity (>85% identity). qacA, qacB, qacR, sin, orf186, and Δorf186 (a truncated copy of orf186) are represented by arrows, with the orientation of the arrow indicating the direction of transcription. The insertion sequences IS256 and IS257 are represented by solid and hatched boxes, respectively. Additional restriction sites shown are abbreviated as follows: C (ClaI), H (HindIII), and P1 (PvuI).