Two component systems: versatile molecular circuits

Abstract

To survive, organisms must adapt to sudden environmental changes that exert a selective pressure and therefore, their chances of survival depend on their ability to respond quickly and accurately. Adapting to these changes is closely linked to the correct perception and transmission of stimuli and the generation of appropriate responses. Two component systems (TCS) allow different bacteria, fungi, slime molds and plants to regulate their physiology according to the environmental conditions. In these molecular circuits, the mechanism of communication between modules is the consecutive phosphorylation of His and Asp residues located in sensor histidine kinase and  response  regulator protein pairs. This review highlights the most relevant features of TCS and their role in the perception and response to diverse stimuli. Finally, the differences between prokaryotic and eukaryotic TCS are illustrated using the osmotic response in Escherichia coli and Saccharomyces cerevisiae.