Outer Membrane Modification System (3 part TCS of Pho, Pmr, Rcs)

• an example of TCS is outer membrane modification/surface protection consisting of 3 TCSs, (HK/RR format)

  1. PhoQ/PhoP Mg system

  • PhoQ HK off when Mg bound, on when low Mg -> PhoQ auto phosphorylates then transfers to PhoP which becomes TF for pmrD gene

  
• an example of TCS is outer membrane modification/surface protection consisting of 3 TCSs, HK/RR

  2. PmrB/PmrA Fe system

  • PmrB HK off when Fe bound, on when low Fe -> PmrB auto phosphorylates then transfers to PmrA which becomes TF for ugd gene
  • *PmrD stabilizes PmrA post transcriptionally and independently of PmrB HK because PmrA is prone to dephosphorylation

  
• an example of TCS is outer membrane modification/surface protection consisting of 3 TCSs, HK/RR

  3. RscC/RcsB envelope stress

  • RscC HK turns on when cell envelope stress occurs -> RscC auto phosphorylates then transfers to RscB RR which (along with RscA) becomes TF for ugd

  1. ***ugd gene product is needed for Pmr regulated modification of LPS and Rcs dependent capsule production