Among the genes were several previously characterized PmrA-activated genes : pmrH ( STM2297 ) , pmrF , pmrC ( yjdB ) , pmrA ( basR ) , pmrB ( basS ) , yibD and pmrG ( ais ) .
On the other hand , neither Ca2 + nor Co2 + , K + , Ni2 + , Zn2 + , Mn2 + , Cu2 + , Ga3 + or Ru3 + ( at concentrations of up to 1 mM ) could induce PmrA-activated genes ( Wosten et al. , 2000 ) or kill the DpmrC ugd pmrG triple mutant ( data not shown ) .
Inactivation of the PmrA-activated genes mediating the modification of the two lipid-A phosphates and the Hep ( II ) phosphate in the core region resulted in a strain ( i.e. the DpmrC ugd pmrG triple mutant ) that was as susceptible to Fe ( III ) as the DpmrAB mutant ( Table 1 ) and that bound more iron than the wild-type strain ( Fig. 1B ) .
DpbgE2 DpbgE3 pbgP Ugd DpbgE2/vector DpbgE2/ppbgE2 DpbgE3/vector DpbgE3/ppbgE3 pbgPDpbgE2 pbgPDpbgE3 ugdDpbgE2 ugdDpbgE3 DpmrAB/vector DpmrAB/ppmrAB DpmrAB/vector DpmrAB/ppbgE2 DpmrAB/ppbgE3 DpmrAB/ppbgE2E3 DpmrG DpmrC DpbgPE Dugd DyibD DpbgPE pmrC ugd pmrG yibD DpmrC ugd pmrG yibD DpmrC ugd DpmrC pmrG DpmrC yibD DyibD ugd DyibD pmrG Dugd pmrG DpmrC ugd yibD DpmrC pmrG yibD Dugd pmrG yibD DpmrC ugd pmrG pmrA505DpmrC ugd pmrG DpmrC ugd pmrG/vector DpmrC ugd pmrG/ppmrC DpmrC ugd pmrG/pugd DpmrC ugd pmrG/ppmrG DpmrG pbgPE DpmrC pbgPE DpmrC pbgPE pmrG The PmrA-activated ugd , pbgP , pmrC and pmrG genes are required for Fe ( III ) resistance To examine whether the pmrG and pmrC genes are necessary for Fe ( III ) resistance , we constructed strains deleted for the chromosomal copies of these genes ( see Experimental procedures ) .
Furthermore , a strain deleted for of all three pmrC , ugd and pmrG genes and harbouring the pmrA505 allele , which encodes a PmrA protein that promotes transcription of PmrA-activated genes even under noninducing conditions ( Kox et al. , 2000 ) , was as susceptible to Fe ( III ) as the DpmrAB mutant ( Table 1 ) .