Amplification of signaling activity of the are two-component system of Escherichia coli by anaerobic metabolites - An in vitro study with different protein modules

In Escherichia coli, changes in redox condition of growth are sensed and si gnaled by the Are two-component system. This system consists of ArcB as the membrane-associated sensor kinase and ArcA as the cytoplasmic response reg ulator. ArcB is a tripartite kinase, possessing a primary transmitter, a re ceiver, and a secondary transmitter domain that catalyzes the phosphorylati on of ArcA via a His --> Asp --> His --> Asp phosphorelay, as well as the d ephosphorylation of ArcA-P by a reverse phosphorelay. When ArcA and ArcB we re incubated with ATP, the peak levels of phosphorylated proteins increased in the presence of the fermentation metabolites D-lactate, acetate, or pyr uvate. In this study, we report that these effecters accelerate the autopho sphorylation activity of ArcB and enhance the transphosphorylation of ArcA, but have no effect on the dephosphorylation of ArcA-P. Moreover, the prese nce of the receiver domain of ArcB is essential for the effecters to influe nce the autophosphorylation rate of the primary transmitter domain of ArcB.