Sensory Transduction in Bacterila Chemotaxis

Publisher Summary This chapter discusses sensory transduction in bacterial chemotaxis and presents the conventional pathways of excitation and adaptation. The basic sensory-receptor system of enteric bacteria consists of only five conventional receptors and three transducers to which those recognition sites are linked. The conventional components and the unconventional systems are discussed in the chapter. Many membrane-active compounds are chemotactic agents for enteric bacteria. Stimulation of cells by a number of these compounds is correlated with changes in intracellular pH. The three conventional transducer proteins—Tsr, Tar, and Trg—are structurally complex to a degree not anticipated by simple models. During adaptation to conventional attractant stimuli or repellents, the level of methylation of the appropriate transducer population changes at a constant rate to reach a new level maintained in parallel with the adapted state. Excitation by repellents is mediated by a perturbation of transducers independent of conventional ligand-recognition site. The current rate of progress in characterizing the molecular components of this system promises an elucidation of many of its basic mechanisms in the near future.