Among the genes were several previously characterized PmrA-activated genes : pmrH ( STM2297 ) , pmrF , pmrC ( yjdB ) , pmrA ( basR ) , pmrB ( basS ) , yibD and pmrG ( ais ) .
Activation of pmrC by PmrA suggests that the consequent pEtN modifications , are up-regulated during infection of the mouse
Activation of pmrC by PmrA suggests that these loci , are up-regulated during infection of the mouse
Although a non-cytotoxic form of polymyxin B -- termed polymyxin B nonapeptide ( Vaara and Vaara , 1983 ) -- could partially protect a Salmonella pmrA mutant from Fe ( III ) - mediated killing ( Chamnongpol et al. , 2002 ) inactivation of the PmrA-activated loci responsible for the lipid-A modification with 4-aminoarabinose ( i.e. pbgP ) or phosphoethanolamine ( i.e. pmrC ) did not render the organism susceptible to Fe ( III ) ( Lee et al. , 2004 ) .
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 ) .
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 ) .
For example , activation of the PmrA/PmrB system ( 26 , 27 ) by growing Salmonella in media containing a high ( 10 mM ) Mg2 + concentration and then shifting it to media containing a low 2 + 3 + ( 50 mM ) Mg concentration and 100 mM Fe resulted in an increase in the mRNA levels corresponding to the PmrA-activated pbgP and pmrC genes , which peaked and then reached new steady-state levels ( fig .
S1 ) and that the ssrB promoter mutation had no effect on the expression of the PmrA-activated pmrC gene ( Fig. 5C ) .