Potassium ions are the most abundant cation and potassium transport is essential in maintaining cellular homeostasis through the regulation of cell turgor and cytoplasmic pH. It allows bacteria to grow and survive, therefore, the potassium pool needs to be strictly controlled, which is mainly performed by transport systems that contain a KTN domain. The potassium efflux system, Kef, is such a KTN-bearing system and it is widespread among Gram negative bacteria. The system provides protection against harmful electrophiles through cytoplasmic acidification. Kef is a glutathione-regulated protein: it is inhibited by glutathione (GSH), but it becomes activated by binding glutathione-S-conjugates (GSX), that are formed in the presence of electrophiles. GSH or GSX are bound in the same pocket that is located in a cytosolic regulatory domain which controls the K+ flux. Previous studies already showed that bacterial growth is inhibited when the gating of Kef is manipulated, which makes Kef a potential target for developing novel antibacterial drugs. Structure-Function studies have already lead to a better understanding of the regulation of potassium efflux activity, but no quantitative analyses had been performed until now. A simplified model Kef system (SdKef) is presented and a novel assay was developed that provided new insights into the structural components necessary for the gating of Kef. This assay makes the search for modulators of Kef, and therefore potential novel antibacterial drugs, more easily accessible. Another objective was to identify the nucleotide(s) bound and to determine its role in controlling the Kef system. This nucleotide was identified as AMP which is essential for stability of the Kef system.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:685278 |
| Date | January 2016 |
| Creators | Ekkerman, Silvia |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=229706 |
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