Kinetic model for signal binding to the Quorum sensing regulator LasR.
Kinetic model for signal binding to the Quorum sensing regulator LasR.
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DOI：
10.3390/ijms140713360
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发表时间：
2013-06-27
影响因子：
5.6
通讯作者：
Sams T
中科院分区：
文献类型：
--
作者：
Claussen A;Jakobsen TH;Bjarnsholt T;Givskov M;Welch M;Ferkinghoff-Borg J;Sams T
我们提出了机会致病菌铜绿假单胞菌中las调控激活的动力学模型。该模型基于体外数据，并考虑了两个OdDHL信号分子结合的激光二聚化和连续激活。实验研究了在大肠杆菌背景下，主动激光共振群体感应调节器的产生与信号分子浓度的关系。通过GFP报告子与天然lasB启动子表达的lasB融合来监测调节因子的功能活性。新数据表明，激光共振二聚体的活性形式与两个信号分子协同结合，达到饱和的时间尺度与信号分子浓度无关。这有利于二聚化调节因子免受蛋白酶的保护，并在通过结合两个连续的信号分子激活时保持保护。在没有信号分子的情况下，二聚化的调节因子可以通过单体的蛋白水解周转解离和降解。这解决了我们的数据和最近的报道之间的明显矛盾，即当激光共振的诱导停止时，完全保护的二聚体能够“降解”。
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.
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