The key control step in E. coli chemotaxis is regulation of CheA kinase activity by
a set of four transmembrane chemoreceptors. The receptor dimers can form trimeric
complexes (trimers of dimers), and these trimers can be joined by a bridge thought to
consist of a CheW monomer, a CheA dimer, and a second CheW monomer. It has been
proposed that trimers of receptor dimers may be joined by CheW-CheA dimer-CheW
links to form an extended hexagonal lattice that may be the structural basis of the
chemoreceptor patches seen in E. coli. The receptor/CheA/CheW ternary complex is a
membrane-spanning allosteric enzyme whose activity is regulated by protein
interactions. The study presented in this dissertation investigated intermolecular and
intramolecular interactions that affect the chemotactic signal processing. I have
examined functional interactions between the serine receptor Tsr and the aspartate
receptor Tar using a receptor coupled in vitro phosphorylation assay.
The results reveal the emergent properties of mixed receptor populations and
emphasize their importance in the integrated signal processing that underlies bacterial
chemotaxis. A mutational analysis of the extreme C-terminus (last fifty residues) of Tar
is also presented. The results implicate the receptor C-terminus in maintenance of baseline receptor activity and in attractant-induced transmembrane signaling. They also
suggest how adaptive methylation might counteract the effects of attractant binding.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1337 |
| Date | 15 May 2009 |
| Creators | Lai, Runzhi |
| Contributors | Manson, Michael D. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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