TABLE 1

Sensitivity of AHL receptors to cognate signals

OrganismReceptorSignalEC50aE. coli EC50b
P. aeruginosaLasR3OC12-HSL593 ± 128 nM12.9 ± 3.6 nM
RhlRC4-HSL>100 µMd122 ± 17 µM
QscR3OC12-HSLc1.90 ± 0.27 µM53.4 ± 11.3 nM
B. thailandensisBtaR1C8-HSL50.5 ± 4.6 nM10.5 ± 3.6 nM
BtaR23OHC10-HSL15.0 ± 5.3 nM60.6 ± 16.0 nM
V. fischeriLuxR3OC6-HSL272 ± 15 nMNT
C. violaceumCviRC6-HSL83.4 ± 24.5 nMNT
  • a EC50 is the concentration required for half-maximal activity of the receptor in its native host.

  • b EC50 values for activation of receptors heterologously expressed in E. coli (DH5α). NT, not tested.

  • c QscR is an orphan/solo receptor and does not have a paired signal synthase, but it does respond to 3OC12-HSL produced by LasI.

  • d RhlR activity was not saturated at 1 mM C4-HSL.