Study of the TmoS/TmoT two-component system: towards the functional characterization of the family of TodS/TodT like systems.
Bottom Line: Tightest ligand binding was observed for toluene (K(D) = 150 nM), which corresponds to the highest affinity measured between an effector and a sensor kinase.Other TmoS ligands, termed antagonists, failed to increase TmoS autophosphorylation, which resulted in their incapacity to stimulate gene expression in vivo.Among these ligands, toluene was the most potent inducer of both promoter activities.
Affiliation: Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda 1, Granada, Spain. .Show MeSH
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Mentions: Figure 3 shows the titration of TmoS with benzene, toluene and ethylbenzene and the derived thermodynamic parameters are given in Table 1. In all cases downwards going peaks are observed indicative of exothermic heat changes implying favourable enthalpy changes. Binding curves for benzene and toluene were very similar and KD values of 170 and 150 nM were determined respectively. These affinities are around 4.5 times higher than the corresponding values obtained for TodS. To our knowledge, these values correspond to the highest affinities observed for an interaction of a SK with effector molecules. Ethylbenzene bound with a weaker affinity of 1.5 µM, which, however, was also tighter than its binding at TodS.
Affiliation: Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda 1, Granada, Spain. .