FIG 1.

Organization of the pmrCAB operon and flanking regions in K. pneumoniae KPB-2 and location of the T245G mutation in the pmrB gene, leading to the L82R amino acid substitution in the transmembrane domain of the PmrB protein. The locations of primers used for PCR cloning of the pmrB gene for complementation experiments are indicated by thin black arrows. A, AvaI_pmrAB_F; E, EcoRI_pmrAB_R. In Salmonella enterica, the pmrC gene product catalyzes the addition of phosphoethanolamine to lipid A, which also could contribute to decreasing the negative charge of lipid A (14). The role of pmrC in K. pneumoniae has not been specifically reported, but given the conservation of pmrC and of the whole Pmr system, it likely retains the same function.