Biochemistry and regulation of CheA in Bacillus subtilis chemotaxis
Garrity, Liam Fournier
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Permalink
https://hdl.handle.net/2142/20879
Description
Title
Biochemistry and regulation of CheA in Bacillus subtilis chemotaxis
Author(s)
Garrity, Liam Fournier
Issue Date
1996
Doctoral Committee Chair(s)
Ordal, George W.
Department of Study
Biochemistry
Discipline
Biochemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Molecular
Chemistry, Biochemistry
Language
eng
Abstract
Bacterial chemotaxis is one of the most well understood signal transduction processes in biology. By controlling the direction of flagella rotation, this process allows the organism to sense changes in its surroundings and migrate toward more favorable environments. The process of chemotaxis is controlled by the activity of an autophosphorylating histidine kinase, CheA. The work described in this thesis shows that Bacillus subtilis CheA differs from other members of this family of bacterial histidine kinases in two respects: it is able to achieve its maximum phosphorylation potential at very low ATP concentrations, and the phosphorylated form of the enzyme is very stable in the presence of ADP and other potential phosphoryl group acceptors. We have long hypothesized that attractant-bound methyl-accepting chemotaxis proteins (MCPs) in B. subtilis increase the activity of CheA. Asparagine-bound McpB has been shown here to increase CheA activity in vitro, the first example of activation of a two-component signal transducing kinase by its proposed environmental ligand to date. Studies on the enteric chemotaxis system revealed that taxis toward certain sugars is mediated solely through a separate phosphoenolpyruvate-dependent phosphotransferase system (PTS), involved in sugar transport. In B. subtilis, we have determined that taxis toward PTS carbohydrates is mediated both by MCPs and the PTS. Finally, a restriction map of the distal end of the 26kb fla/che operon has been deduced, which will be of value in attempts to clone additional chemotaxis genes in B. subtilis.
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