Medical College of Wisconsin
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CheB is required for behavioural responses to negative stimuli during chemotaxis in Bacillus subtilis. Mol Microbiol 2000 Jan;35(1):44-57

Date

01/13/2000

Pubmed ID

10632876

DOI

10.1046/j.1365-2958.2000.01676.x

Scopus ID

2-s2.0-0033963325   42 Citations

Abstract

The methyl-accepting chemotaxis protein, McpB, is the sole receptor mediating asparagine chemotaxis in Bacillus subtilis. In this study, we show that wild-type B. subtilis cells contain approximately 2,000 copies of McpB per cell, that these receptors are localized polarly, and that titration of only a few receptors is sufficient to generate a detectable behavioural response. In contrast to the wild type, a cheB mutant was incapable of tumbling in response to decreasing concentrations of asparagine, but the cheB mutant was able to accumulate to low concentrations of asparagine in the capillary assay, as observed previously in response to azetidine-2-carboxylate. Furthermore, net demethylation of McpB is logarithmically dependent on asparagine concentration, with half-maximal demethylation of McpB occurring when only 3% of the receptors are titrated. Because the corresponding methanol production is exponentially dependent on attractant concentration, net methylation changes and increased turnover of methyl groups must occur on McpB at high concentrations of asparagine. Together, the data support the hypothesis that methylation changes occur on asparagine-bound McpB to enhance the dynamic range of the receptor complex and to enable the cell to respond to a negative stimulus, such as removal of asparagine.

Author List

Kirby JR, Niewold TB, Maloy S, Ordal GW

Author

John Kirby PhD Chair, Center Associate Director, Professor in the Microbiology and Immunology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Bacillus subtilis
Bacterial Proteins
Blotting, Western
Chemoreceptor Cells
Chemotaxis
Fluorescent Antibody Technique
Membrane Proteins
Methylation
Mutation