Characterization of pACK4, a mobilizable plasmid from Staphylococcus simulans biovar staphylolyticus

Complete nucleotide sequences of plasmids pACK2 and pACK5 from Staphylococcus simulans biovar staphylolyticus

Staphylococcus simulans biovar staphylolyticus contains five plasmids, designated pACK1-pACK5. Recently, the nucleotide sequences of three of these plasmids, pACK1, pACK3, and pACK4, were reported. In order to complete the characterization of these five plasmids, the nucleotide sequences of the two remaining plasmids, pACK2 (37683 bp) and pACK5 (3191 bp), were determined. pACK5 is comprised of two regions, one with 85% identity at the nucleotide level to a region of pWBG1773 and another region with an ORF that shares no significant similarity to sequences previously described in GenBank. pACK2 encodes proteins for cadmium resistance and enhanced biofilm formation. The similarities at the nucleotide level among regions of the plasmids of S. simulans bv. staphylolyticus suggest that these plasmids have undergone multiple intermolecular rearrangements.

Complete nucleotide sequences of plasmids pACK1 and pACK3 from Staphylococcus simulans biovar staphylolyticus

Staphylococcus simulans biovar staphylolyticus contains five plasmids designated pACK1-pACK5. The complete nucleotide sequences of pACK1 (55171bp) and pACK3 (28613bp) were determined and sequence comparison revealed that the entire pACK3 sequence is present on pACK1 (99.98% identical on the nucleotide level) with the sequence unique to pACK1 located between sin and blaZ, which are adjacent in pACK3. The common region contains the staphylococcal beta-lactamase transposon Tn552 and ORFs with similarity to genes encoding a serine-recombinase, enzymes involved in pantothenate biosynthesis, and components of the secA2 region involved in bacterial adherence to host tissues. The common region also contains a cluster of six ORFs that share no significant similarity to sequences previously described in GenBank. The region unique to pACK1, in addition to the genes for lysostaphin and lysostaphin resistance, contains ORFswith similarity to genes encoding a toxin-antitoxin addiction system and proteins involved in plasmid partitioning. The unique region also contains several ORFs that are similar to genes typically found on the chromosome such as those encoding catalase, ferrochelatase, and an enzyme involved in pantothenate biosynthesis. In pACK1, the ends of the unique region contain IS431 elements with direct repeats marking the points where the two plasmid sequences diverge. Several observations suggest that pACK1 was derived by insertion of the unique region into pACK3.