Part:BBa_K339006

CpxP Promoter
The CpxP promoter is a stress-activated promoter for a periplasmic regulator included in the Cpx regulon. It was taken directly from the E. coli genome through PCR.

Usage and Biology

CpxP is a protein of the Cpx regulon which is a periplasmic stress-activated regulon in E. coli. The CpxP protein is produced through activation of the corresponding promoter by stress. Some possible stresses that activate the regulon are elevated pH, accumulation of pilus subunits, the presence of misfolded protein or aggregate bodies (masses of misfolded proteins that group together to form insoluble bodies that remain undegraded within the cell). One protein known to activate the Cpx regulon is New lipoprotein E (NlpE). In standard conditions, the CpxP protein is docked onto CpxA, which is a transmembrane histidine kinase that is phosphorylated when CpxP is detached (Keller and Hunke, 2009). In the presence of misfolded proteins in the periplasm, CpxP detaches and binds to the misfolded protein within the periplasm (Raivio et al., 2000). Out of the most known proteins in the Cpx regulon (CpxR, CpxP, and DegP), CpxP is proposed to show the highest activity in the presence of misfolded protein.

http://i872.photobucket.com/albums/ab287/iGEMCalgary_2010/Cpxresponse.png

This diagram illustrates that the CpxP promoter is the most sensitive in the stress regulon. CpxP is followed by CpxR and DegP respectively. These were selected because they are some of the most sensitive in the periplasmic stress detection pathways

References
Keller, R., and Hunke, S., 2005. Misfolded maltose binding protein MalE219 induces the CpxRA envelope stress response by stimulating phosphoryl transfer from CpxA to CpxR. Research in Microbiology 160(6):396-400

Raivio, T., Laird, M., Joly, J., and Silhavy, T. 2000. Tethering of CpxP to the inner membrane prevents spheroplast induction of the Cpx envelope stress response. Molecular Microbiology 37(5):1186-1197