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Dissertation
Studies of the Full-length Histidine Kinase VanSA in Detergent: From Sensing Vancomycin to Regulating its Response Regulator, VanRA
Doctor of Philosophy (Ph.D.), Drexel University
Mar 2018
DOI:
https://doi.org/10.17918/D8g663
Abstract
VanSA is a sensor histidine kinase responsible for detecting vancomycin and activating expression of vancomycin-resistance genes in vancomycin-resistant bacteria. When VanSA senses vancomycin it autophosphorylates and then transfers that phosphate to the transcription factor VanRA. Phospho-VanRA then activates transcription of the enzymes that remodel the cell wall to avert vancomycin's effects. In the absence of vancomycin VanSA has a third enzymatic activity, phosphatase activity, which it uses to maintain VanRA in an inactivated state. This is required because VanRA can be non-specifically phosphorylated by small molecule phospho-donors and, potentially, other histidine kinases (referred to as cross-talk). To study this VanRSA signaling system we purified the individual components including the full-length VanSA protein solubilized in detergent. An ongoing question in the field is whether VanSA detects vancomycin directly or detects a downstream effect of vancomycin. We found that vancomycin does not affect the activity of purified full-length VanSA in detergent. We also found that a non-partner histidine kinase, PhoR, phosphorylates VanRA much more slowly than its cognate partner VanSA does. PhoR binds VanRA with an affinity comparable to that of VanSA, indicating that the binding affinity alone does not confer partner-like signaling.
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Details
- Title
- Studies of the Full-length Histidine Kinase VanSA in Detergent
- Creators
- Elizabeth C. Upton - DU
- Contributors
- Patrick J. Loll (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- x, 151 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology; College of Medicine; Drexel University
- Other Identifier
- 7965; 991014632176604721