The Tsr chemoreceptor/CheW/CheA ternary complex as an allosteric enzyme /
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| Format: | Thesis eBook |
| Language: | English |
| Published: |
[College Station, Tex.] :
[Texas A&M University],
[2006]
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| Subjects: | |
| Online Access: | Link to OAK Trust copy |
| Abstract: | The transmembrane serine receptor Tsr associates with a coupling protein, CheW, and a histidine kinase, CheA, to form a ternary complex that regulates the activity of CheA. CheA activity is inhibited by binding of L-serine to Tsr. This work aims to characterize the ligand-binding properties of Tsr and the inhibitory effect of L-serine on CheA activity. The periplasmic domain of Tsr (pTsr) was purified and characterized. Analytical gel filtration and analytical ultracentrifugation indicated that binding of L-serine promotes dimerization. The binding stoichiometry and dissociation constant for binding of L-serine to pTsr were determined by fluorescence spectroscopy. As protein concentration decreased, the dissociation constant increased. A working model was proposed to account for the interactions between L-serine and pTsr. The activity of CheA in a ternary complex with full-length Tsr and CheW was analyzed by measuring the production of [³²P]-phospho-CheY. (Phospho-CheY is the product of CheA catalysis.) The results revealed that binding of L-serine decreased CheA activity without changing its affinity for ATP. These findings suggest that the allosteric effect of L-serine on CheA activity might occur through V-type inhibition. Optimization of an alternative, continuous, non-radioactive assay for CheA is underway. |
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| Item Description: | "Major Subject: Biochemistry" Title from author supplied metadata (automated record created on Sep. 15, 2006.) Vita. Abstract. Electronic resource. |
| Format: | Mode of access: World Wide Web. System requirements: World Wide Web access and Adobe Acrobat Reader. |
| Bibliography: | Includes bibliographical references. |