Quinones as the redox signal for the Arc two-component system of bacteria

The Arc two-component signal transduction system mediates adaptive response s of Escherichia coli to changing respiratory conditions of growth. Under a naerobic conditions, the ArcB sensor kinase autophosphorylates and then tra nsphosphorylates ArcA, a global transcriptional regulator that controls the expression of numerous operons involved in respiratory or fermentative met abolism. We show that oxidized forms of quinone electron carriers act as di rect negative signals that inhibit autophosphorylation of ArcB during aerob iosis. Thus, the Arc signal transduction system provides a link between the electron transport chain and gene expression.