TY - JOUR

T1 - Kinetic Model for Signal Binding to the Quorum Sensing Regulator LasR

AU - Claussen, Anetta

AU - Jakobsen, Tim Holm

AU - Bjarnsholt, Thomas

AU - Givskov, Michael

AU - Welch, Martin

AU - Ferkinghoff-Borg, Jesper

AU - Sams, Thomas

PY - 2013

Y1 - 2013

N2 - We propose a kinetic model for the activation of the las regulon in the opportunistic pathogen Pseudomonas aeruginosa. The model is based on in vitro data and accounts for the LasR dimerization and consecutive activation by binding of two OdDHL signal molecules. Experimentally, the production of the active LasR quorum-sensing regulator was studied in an Escherichia coli background as a function of signal molecule concentration. The functional activity of the regulator was monitored via a GFP reporter fusion to lasB expressed from the native lasB promoter. The new data shows that the active form of the LasR dimer binds two signal molecules cooperatively and that the timescale for reaching saturation is independent of the signal molecule concentration. This favors a picture where the dimerized regulator is protected against proteases and remains protected as it is activated through binding of two successive signal molecules. In absence of signal molecules, the dimerized regulator can dissociate and degrade through proteolytic turnover of the monomer. This resolves the apparent contradiction between our data and recent reports that the fully protected dimer is able to "degrade" when the induction of LasR ceases.

AB - We propose a kinetic model for the activation of the las regulon in the opportunistic pathogen Pseudomonas aeruginosa. The model is based on in vitro data and accounts for the LasR dimerization and consecutive activation by binding of two OdDHL signal molecules. Experimentally, the production of the active LasR quorum-sensing regulator was studied in an Escherichia coli background as a function of signal molecule concentration. The functional activity of the regulator was monitored via a GFP reporter fusion to lasB expressed from the native lasB promoter. The new data shows that the active form of the LasR dimer binds two signal molecules cooperatively and that the timescale for reaching saturation is independent of the signal molecule concentration. This favors a picture where the dimerized regulator is protected against proteases and remains protected as it is activated through binding of two successive signal molecules. In absence of signal molecules, the dimerized regulator can dissociate and degrade through proteolytic turnover of the monomer. This resolves the apparent contradiction between our data and recent reports that the fully protected dimer is able to "degrade" when the induction of LasR ceases.

U2 - 10.3390/ijms140713360

DO - 10.3390/ijms140713360

M3 - Journal article

C2 - 23807499

VL - 14

SP - 13360

EP - 13376

JO - International Journal of Molecular Sciences (Online)

JF - International Journal of Molecular Sciences (Online)

SN - 1661-6596

IS - 7

ER -