Signal transduction in bacteria: molecular mechanisms of stimulus-response coupling.

In bacteria, adaptive responses to changing environmental conditions are mediated by signal transduction systems that involve modular protein domains. Despite great diversity in the integration of domains into different systems, studies of individual components have revealed molecular strategies that are widely applicable. Studies of receptors have advanced our understanding of how information is transmitted across membranes, the determination of three-dimensional structures of domains of histidine protein kinase domains and response regulator proteins has begun to reveal the molecular basis of signaling via two-component phosphoryltransfer pathways, and the description of 'eukaryotic-like' protein domains involved in bacterial signaling has emphasized the universality of intracellular signaling mechanisms.