Signaling and sensory adaptation in Escherichia coli chemoreceptors: 2015 update

• Escherichia coli uses transmembrane chemoreceptors to detect environmental chemicals.
• Chemoreceptors convey signals through dynamic shifts in coupled structural elements.
• Core signaling complexes contain six receptors coupled to one kinase molecule.
• Networked core complexes form cooperative, high-amplification signaling arrays.

Motile Escherichia coli cells track gradients of attractant and repellent chemicals in their environment with transmembrane chemoreceptor proteins. These receptors operate in cooperative arrays to produce large changes in the activity of a signaling kinase, CheA, in response to small changes in chemoeffector concentration. Recent research has provided a much deeper understanding of the structure and function of core receptor signaling complexes and the architecture of higher-order receptor arrays, which, in turn, has led to new insights into the molecular signaling mechanisms of chemoreceptor networks. Current evidence supports a new view of receptor signaling in which stimulus information travels within receptor molecules through shifts in the dynamic properties of adjoining structural elements rather than through a few discrete conformational states.