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A Multi-Faceted Study of the Voltage Sensor in Voltage-Gated Potassium Channels Open Access
- Other title
- Type of item
- Degree grantor
University of Alberta
- Author or creator
Sand, Rheanna M.
- Supervisor and department
Gallin, Warren (Biological Sciences)
- Examining committee member and department
Accili, Eric (UBC, Cellular and Physiological Sciences)
Ali, Declan (Biological Sciences)
Pilgrim, David (Biological Sciences)
Smith, Peter (Pharmacology)
Hall, Dennis (Chemistry)
Department of Biological Sciences
Physiology, Cell, and Developmental Biology
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
Voltage-gated potassium (Kv) channels regulate the flow of potassium ions across the cell membrane of nerves and muscles. Proper functioning of these and other voltage-gated ion channels is critical for an animal to sense the environment and respond quickly to stimuli. Dysfunctional Kv channels, whether inherited or induced by pharmacological agents, can be the root cause of disease or death. Kv proteins have a voltage sensing domain that physically moves across the cell membrane during activation, but a complete picture of this process is lacking. The work presented in this thesis addressed the structure-function relationships within the voltage sensing domain of Kv channels using three distinct approaches. First, a previously unknown jellyfish Kv channel was sequenced in order to diversify the pool of known channels, which is heavily biased toward mammalian sequences. The voltage-dependent properties of this new channel were compared to those of known, mammalian channels to better understand the processes of voltage-dependent gating. Secondly, a well-studied mammalian channel was altered in a way that allowed for an estimation of the atomic distance between two helices in the voltage sensing domain. Molecular dynamics simulations were used to calculate Gibbs free energy difference between two states, which was compared to experimental data to triangulate the most likely actual distance between the S3 and S4 helices. Lastly, several experiments were undertaken to locate the pharmacological receptor site on Kv channels for 6-bromo-2-mercaptotryptamine or BrMT. This gastropod toxin is a modulator of Kv channels that interferes with the gating process. Attempts to locate that binding site through mutagenesis and electrophysiological assay were not conclusive. In summary, the atypical behavior of the novel jellyfish channel demonstrated the utility of isolating and characterizing Kv sequences from basally-branching organisms; the comparison of free energy from molecular dynamics with that of real-world data allowed us to estimate atomic distances in a Kv channel; and BrMT may represent a new mechanistic class of Kv channel blocker but more work is needed to determine the binding site.
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
- Citation for previous publication
Sand, R. M., Atherton, D. M., Spencer, A. N. and Gallin, W. J. (2011). jShaw1, a low-threshold, fast-activating Kv3 from the hydrozoan jellyfish Polyorchis penicillatus. Journal of Experimental Biology 214, 3124-3137.
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File author: Rheanna Sand
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File language: en-CA