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Bacterial chemotaxis is widely studied because of its accessibility and because it incorporates processes that are important in a number of sensory systems: signal transduction, excitation, adaptation, and a change in behavior, all in response to stimuli. Quantitative data on the change in behavior are available for this system, and the major biochemical(More)
Motile but generally nonchemotatic (che) mutants of Escherichia coli were isolated by a simple screening method. A total of 172 independent mutants were examined, and four genes were defined on the basis of mapping and complemenvestigated by determining their null phenotypes with nonsense or bacteriophage Mu-induced mutations. The cheA and cheB products(More)
proximity. Although the general sequence of events is similar for all of these systems, each pathway exhibits variations on this basic scheme that tailor it to a particular sensory task. The modular design of the two-component paradigm has facilitated the evolutionary construction of a variety of signal transduction circuits, all of which utilize phosphoryl(More)
The histidine protein kinase CheA plays a central role in the bacterial chemotaxis signal transduction pathway. Autophosphorylated CheA passes its phosphoryl group to CheY very rapidly (k(cat) approximately 750 s(-)(1)). Phospho-CheY in turn influences the direction of flagellar rotation. The autophosphorylation site of CheA (His(48)) resides in its(More)
The CheY protein is the response regulator in bacterial chemotaxis. Phosphorylation of a conserved aspartyl residue induces structural changes that convert the protein from an inactive to an active state. The short half-life of the aspartyl-phosphate has precluded detailed structural analysis of the active protein. Persistent activation of Escherichia coli(More)
Chemoreceptors are crucial components in the bacterial sensory systems that mediate chemotaxis. Chemotactic responses exhibit exquisite sensitivity, extensive dynamic range and precise adaptation. The mechanisms that mediate these high-performance functions involve not only actions of individual proteins but also interactions among clusters of components,(More)
Chemoreceptors of the methyl-accepting chemotaxis protein family form clusters, typically at the cell pole(s), in both Bacteria and Archaea. To elucidate the architecture and signaling role of receptor clusters, we investigated interactions between the serine (Tsr) and aspartate (Tar) chemoreceptors in Escherichia coli by constructing Tsr mutations at the(More)
Six Escherichia coli che loci (cheA,-B,-R,-W,-Y, and Z) are located in two adjacent operons that map at minute 42 on the chromosome. Point mutants defective in any of these six functions have aberrant swimming patterns and are generally nonchemotactic. Deletions within the two major che gene operons were isolated in order to examine epistatic interactions(More)