Two-Component Systems (TCSs) of Bacteria Share Some Similarities with Neurons

In humans and other higher life forms, electrochemical impulses flow through neurons and reach the central nervous system (CNS). In bacteria, signaling molecules bind to sensors on the cell surface, in the cell wall, and at the cell membrane, triggering a cascade of phosphorylation reactions. Two-component systems (TCSs) are the primary signal transduction mechanisms in bacteria, archaea, and higher life forms such as plants. Response regulators (RRs) are triggered to regulate gene expression. Although TCSs differ completely in structure and complexity from neurons, both systems function as biological circuits designed to receive and process chemical signals and trigger a response. TCSs may serve as computational models to study basic molecular components in complex logic operations, such as AND, OR, and NOT gates. Studying the similarities between TCSs and neurons may help uncover universal mechanisms underlying the processing of information (stimuli) and the reaction thereto. This review is not intended to draw direct comparisons between the two signal transduction networks and does not, in any way, suggest that neurons evolved from TCSs. The review uncovers universal rules whereby living matter processes environmental data and optimizes responsive processes across completely different domains of life.