The Chemotaxis Phosphatases cheC and cheX

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biochemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Muff, Travis John

Contributors dc:contributor

• Ordal, George W.

• Biology, Microbiology

Language dc:language

eng

Identifier

(MiAaPQ)AAI3290327

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/84843