We have investigated the transcriptional regulation and the interaction of the response regulator PhoP with the promoter regions of the PhoP-activated loci phoPQ , mgtA , slyB , pmrD , pcgL , phoN , pagC , and mgtCB .
The ugtL gene is part of a Salmonella-specific gene cluster that includes the PhoP-activated pcgL gene ( 22 ) and the sifB gene , which is expressed in response to the low Mg2 conditions that normally activate the PhoP/PhoQ system ( 23 ) .
The ugtL gene was first identified as part of a Salmonella-specific DNA region harbouring the PhoP-activated pcgL gene , which encodes a D-Ala-D-Ala dipeptidase ( Hilbert et al. , 1999 ) .
PhoP-suppressed genes include prgH and fliC [ 55 -- 57 ] , PhoP-activated genes include pmrAB , another two-component signal transduction system involved primarily in the protection of Salmo-nella to cationic antimicrobial peptides ( CAMP , see below ) [ 58 ] , mgtA and mgtCB encoding Mg transport 2 + systems , phoN , a periplasmic non-specific acid phospha-tase , pcgL encoding a periplasmic D-Ala -- D-Ala dipeptidase , or pagL , pagP and pgtE which contribute to increased resistance to CAMPs [ 59 -- 62 ] .