A mutation in the S. enterica serovar Typhimurium phoQ gene which results in a threonine residue at codon 48 being replaced with an isoleucine results in overexpression of several PhoP-activated genes ( 8 , 19 , 20 , 24 ) .
PhoP-regulated genes were further identified by transcriptional profiling using microarrays of strain CS022 containing a phoQ mutation that results in increased expression of PhoP-activated genes and a phoP null mutant ( W.N. , unpubl .
a phoQ mutation results in increased expression of PhoP-activated genes
Transcriptional regulation of Salmonella virulence -- a phoQ periplasmic domain mutation results in increased net phosphotransfer to PhoP .
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 ) .
If MgtA exerts its regulatory function by removing Mg2 + away from PhoQ , deletion of the mgtA gene should not affect expression of PhoP-activated genes in a strain lacking the phoQ gene .
S. Typhimurium strains with mutations in phoQ that have variable expression of PhoP-activated genes ( pag ) were constructed to study GPL regulation .
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 .