The constitutive phoP gene was placed under the control of an arabinose-inducible promoter to examine the kinetics of PhoP-activated gene induction and the resultant modifications of LPS .
We placed the constitutive phoP gene under the control of an arabinose-inducible promoter and used this to determine the kinetics of activation of several pag genes as well as the modification of lipid-A with 2-hydroxymyristate , which can be added as a result of activation of an unknown PhoP-activated gene ( s ) .
To identify genes necessary for bile resistance , MudJ transposon mutagenesis was performed on a strain containing a phoP mutation that results in constitutive expression of PhoP-activated genes .
The tolB effect appears to be specific to the ugd gene because transcription of the PhoP-activated PmrA-dependent pbgP gene and the PhoP-activated PmrA-independent mgtA gene was not affected by the tolB mutation regardless of the presence of functional phoP or pmrA genes ( Fig. 2A ; data not shown ) .
D. Alignment of the regulatory sequences of the PhoP-activated ugd , phoP , mgtA and mgrB genes .
As expected for a PhoP-activated gene , there was no slyA transcription when bacteria were grown under PhoP-repress-ing conditions ( i.e. 10 mM Mg2 ) , regardless of the presence of a functional phoP gene ( Fig. 4A ) .
We determined that a ugtL pmrA double mutant was as susceptible to polymyxin B as a phoP mutant ( Fig. 3C ) , which suggests that both types of lipid-A modifications may operate at the same time and argues against the participation of other PhoP-regulated genes in resistance to polymxyin B. Thus , the increased polymyxin B susceptibility reported for mutants defective in the PhoP-activated mig-14 , virK and somA genes may be characteristic of the SL1344 genetic background used in those studies ( Brodsky et al. , 2002 ; Detweiler et al. , 2003 ) because derivatives of the 14028s strain deleted for the mig-14 gene or harbouring a MudJ transposon insertion in the virK gene retained wild-type resistance to both polymxyin B and magainin 2 ( our unpublished results ) .
The mRNA lev - encoded products are produced in the correct els of the PhoP-activated mgtA , phoP , pmrD , locales , at the required amounts and for the ap - and mig-14 genes increased after the shift to low propriate extents of time .
Inactivation of the phoP or levels of the PhoP-activated genes increased , phoQ genes renders Salmonella enterica serovar reached a peak that was lower than that obtained Typhimurium five orders of magnitude less when Salmonella was induced at 50 mM Mg2 + virulent for mice and unable to proliferate within ( except for the mgtA gene , which reached the phagocytic cells ( 4-6 ) .
RT-PCR analysis independently showed an NO-dependent downregulation in the transcription of PhoP-activated genes phoP , phoQ , mig-14 and phoN , while RNS treatment did not affect ( e.g. , rpoD ) or even increased ( e.g. , hmpA ) the expression of other loci ( fig. 5B ) .
Our results from primer-extension demonstrate that transcriptions of the identified loci are activated by PhoP because the mRNA level of transcripts is reduced significantly in the phoP mutants grown in low-Mg2 conditions -LRB- Fig .
phoP and slyB are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for LPS modification and CAMP resistance , we identified Udg , EptA , ArnA ( also named PbgP3 or PmrI ) , ArnB ( PbgP1 or PmrH ) , and ArnC ( PbgP2 or PmrF ) .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for CAMP resistance , we identified Udg , EptA , ArnA -LRB- also named PmrI -RRB- .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for CAMP resistance , we identified Udg , EptA , ArnA -LRB- also named PbgP3 -RRB- .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for LPS modification , we identified Udg , EptA , ArnA -LRB- also named PmrI -RRB- .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for LPS modification , we identified Udg , EptA , ArnA -LRB- also named PbgP3 -RRB- .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for CAMP resistance , we identified ArnB .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for LPS modification , we identified ArnB .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for CAMP resistance , we identified PmrH .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for CAMP resistance , we identified PbgP1 .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for LPS modification , we identified PmrH .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for LPS modification , we identified PbgP1 .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for CAMP resistance , we identified ArnC .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for LPS modification , we identified ArnC .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for CAMP resistance , we identified PmrF .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for CAMP resistance , we identified PbgP2 .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for LPS modification , we identified PmrF .
phoP are the most conserved genes in PhoP regulons across the Enterobacteriaceae family , and SlyB can decrease PhoP protein activity .27 SlyA can enhance the overall transcription of PhoP-activated loci .22 IraP is transcriptionally activated by PhoP to stabilize another regulator RpoS .28 For the proteins in the group for LPS modification , we identified PbgP2 .
As shown in Fig. 4C , this motif is also observed in a similar position and in the same orientation in a subset of PhoP-activated genes , including phoP , mgtA , pmrD , yrbL , slyB , and orgB ( 49 ) .
Therefore , the mgtA requirement for normal expression of a subset of PhoP-activated genes does not result from inefficient transcription of the autoregulated phoP gene ( Soncini et al. , 1995 ) in the mgtA mutant ( Fig .
Given that PhoQ is essential to activate the wild-type PhoP protein ( Chamnongpol and Groisman , 2000 ) , we used a strain harboring the phoP * allele , which specifies a PhoP variant that displays enhanced autophosphorylation from acetyl phosphate in-vitro and in-vivo ( Chamnongpol and Groisman , 2000 ) , and thus , can promote transcription of PhoP-activated genes in the absence of PhoQ .
A similar motif is found in the promoters of a subset of PhoP-activated genes , including steA , phoP , mgtA , pmrD , slyB , and orgB ( Fig. 6B ) .
These effects are not specific to the phoP gene because they were also observed with the PhoP-activated mgtC gene ( Fig. 2B ) .
A S. enterica strain expressing PhoQ ( N67D , E112D ) from its normal chromosomal location induced the PhoP-activated phoP gene like the isogenic strain with the wild-type S. enterica phoQ gene ( Fig. 3A ) ; this result argues that these periplasmic residues are not essential for the response to acidic pH. The PhoQ proteins from both S. enterica and S. bongori harbor a histidine residue at position 157 .
Transcription of the PhoP-activated phoP and mgtA genes was higher in wild-type S. enterica than in strains expressing the cadAB genes constitutively when the inducing condition was acidic pH ( Fig. 6C and D ) .