The Cpx system

The E. coli Cpx system was initially identified as a system that regulates the efficiency of plasmid conjugation but is now known to play a more broad role as a regulatory system for envelop stress. The system encodes a membrane-bound histidine kinase (CpxA) and a transcriptional regulatory protein (CpxR) which are similar to proteins found in other bacterial two-component regulatory systems. The Cpx system is, however, novel in that it also involves a third protein, CpxP, which exists in the cytoplasm and likely interacts with protein targets there, as well as CpxA, thereby playing a key role in stress signaling. Our structure of CpxP reveals an intriguing cup-shaped dimeric structure similar to that of the Spy protein chaperone, and suggests regions that may interact with unfolded proteins and CpxA.

Figure 1.
Thede, G. L., Arthur, D. C., Edwards, R. A., Buelow, D. R., Wong, J. L., Raivio, T. L., Glover, J. N. M. (2011) Structure of the periplasmic stress response protein CpxP. J Bacteriol. 2011 Feb 11. [Epub ahead of print]