Peritrichously flagellated bacteria carry out chemotaxis by modulating the frequency
of switching between smooth swimming and tumbling. The tumbling frequency is
controlled by a signal transduction cascade in which transmembrane receptors modulate
the activity of a histidine kinase CheA that transfers phosphate to its cognate response
regulator CheY. The proteins of the chemotaxis signaling cascade are localized to
clusters found primarily at the poles of cells. In this work, the localization of the CheZ
protein, a phosphatase that dephosphorylates CheY~P, is examined. Using a CheZ-GFP
fusion protein, we show that CheZ was localized to the polar receptor patch via
interaction with the short form of CheA (CheAS). Aromatic residues of CheZ near one
end of the elongated CheZ four-helix bundle were determined to be critical for
localization. Aliphatic residues in CheAS were also determined to be critical for CheZ
localization to the receptor patch and substitution of these residues conferred a tumble
bias to swimming cells. A mechanism of CheZ localization is proposed in which the
CheZ apical loop interacts with a binding site formed by dimerization of the P1 domain
of CheAS. The potential role of CheZ localization as a means of coordinating the
rotation state of peritrichously distributed flagella is discussed.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1141 |
| Date | 15 May 2009 |
| Creators | Cantwell, Brian Jay |
| 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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