Bacterial chemotaxis: Conservation and variation on a theme

© 2019 Elsevier Inc. All rights reserved. Most motile bacteria bias their usually random pattern of movement in response to increasing or decreasing concentrations of attractants to increase their chance of moving to an improved environment for growth. Most bacteria are too small to sense a spatial gradient and use temporal sensing to compare conditions now, with those a few seconds ago. They therefore sense, respond and adapt. Almost all motile bacteria use the same core set of proteins: Chemoreceptors (MCPs), a linker, CheW, histidine protein kinase, CheA and diffusible response regulator, CheY. The receptors are reset by a constitutive methyl transferase, CheR, and a responsive methyl esterase, CheB. The core sensing, signaling and adaptation pathway is described. While this core is common to all, this review also describes the variation on this theme, with many species having multiple chemosensory pathways or more complex adaptation and signaling pathways. The chapter also described the mechanisms used to ensure daughter cells inherit chemosensory clusters and the ways in which some chemosensory systems interact with other sensory pathways to produce a global response.