TABLE 1.
Bacterial strains and plasmids used in this study
| Strain or plasmid | Description and source | Reference or source |
|---|---|---|
| Strains | ||
| Y. pestis | ||
| CO92 | Virulent WT Y. pestis biovar Orientalis strain isolated in 1992 from a fatal pneumonic plague case and naturally resistant to polymyxin B | 36, 37 |
| Δlpp CO92 | lpp gene deletion mutant of Y. pestis CO92 | 23 |
| Δpla CO92 | pla gene in-frame deletion mutant of Y. pestis CO92 | This study |
| Δlpp Δpla CO92 | lpp and pla gene double deletion mutant of Y. pestis CO92 | This study |
| CO92(pBR322) | WT Y. pestis transformed with pBR322 (Tcs) | 35 |
| CO92 Δlpp(pBR322) | CO92 Δlpp mutant transformed with pBR322 (Tcs) | 35 |
| CO92 Δpla(pBR322) | CO92 Δpla mutant transformed with pBR322 (Tcs) | This study |
| CO92 Δlpp Δpla(pBR322) | CO92 Δlpp Δpla double mutant transformed with pBR322 (Tcs) | This study |
| CO92 Δpla (pBR322Ypla) | Y. pestis pla deletion mutant complemented via plasmid pBR322Ypla (Tcs) | This study |
| Δlpp Δpla (pBR322Ypla) | Y. pestis lpp and pla double deletion mutant complemented via plasmid pBR322Ypla (Tcs) | This study |
| E. coli SM10 | Strain containing the λpir gene (lysogenized with λpir phage) designed for cloning and propagation of a plasmid with the R6K origin of replication | 38 |
| Plasmids | ||
| pBR322 | Cloning vector for complementation (Tcr Apr) | GE Healthcare |
| pKD13 | Template plasmid for PCR amplification of the Kmr gene cassette flanked by FLP recombinase recombination target sites | 39 |
| pFlp2 | Vector that produces the FLP recombinase to remove the Kmr gene cassette from the mutant | 40 |
| pDMS197 | Suicide vector with a conditional R6K origin of replication (ori) and a levansucrase gene (sacB) from Bacillus subtilis used for homologous recombination | 41 |
| pBR322Ypla | Recombinant plasmid containing the pla gene-coding region and its putative promoter in vector pBR322 used to complement the Δpla mutant of Y. pestis (Tcs) | This study |
| pDMS197plaUDKm | Suicide vector pDMS197-based recombinant plasmid containing the Y. pestis CO92 pla gene up- and downstream flanking DNA fragments with the Kmr cassette used for homologous recombination | This study |