Styrene is sensed by the N-terminal PAS sensor domain of StyS, a double sensor kinase from the styrene-degrading bacterium Pseudomonas fluorescens ST

In Pseudomonas fluorescens ST, the expression of the pathway for the degradation of the toxic compound styrene is induced by the substrate (i.e., styrene) and repressed by alternative carbon sources. This regulation relies on a two-component system consisting of the sensor kinase StyS and the response regulator StyR. StyS belongs to the group of hybrid double sensor kinases, a unique family of sensor kinases having two ATP catalytic domains, each one preceded by a PAS domain. Here, the styrene-based phosphorylation of StyS is reported. Styrene is specifically sensed by the StyS N-terminal PAS sensor domain, enhancing the StyS phosphorylation level.