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Title:The Chemotaxis Phosphatases cheC and cheX
Author(s):Muff, Travis John
Doctoral Committee Chair(s):Ordal, George W.
Department / Program:Biochemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Biology, Microbiology
Abstract:The CheY-P phosphatase CheC is important for chemotactic adaptation. The phosphatase ability of CheC is enhanced nearly five fold upon association with CheD. In this study, CheC mutants were generated in putative active site residues and the CheD binding helix. The mutants were examined for in vivo complementation, CheY binding, and phosphatase ability. Based on the active site mutants, a structural model for the association between CheC and CheY-P is proposed. Further, mutants were identified separating the three known abilities of CheC: CheD binding, CheY binding, and CheY-P phosphatase. Surprisingly, though the CheD and CheY binding mutants were non-functional in vivo, the phosphatase mutant showed partial CheC function. Therefore, the phosphatase ability is not as critical to in vivo CheC function as the ability to bind both CheY-P and CheD. Additionally, it was confirmed that CheY-P causes CheC to become a better binding site for CheD. Based on these results, a model is presented of CheC as a CheY-P induced regulator of CheD. By this model, CheA activation raises levels of CheY-P. The CheC then binds CheY-P and becomes a better binding site for CheD. This sequesters CheD from the chemoreceptors, thus de-exciting them and inducing adaptation of the chemotaxis system.
Issue Date:2007
Description:108 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007.
Other Identifier(s):(MiAaPQ)AAI3290327
Date Available in IDEALS:2015-09-25
Date Deposited:2007

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