Doctor of Philosophy in Pharmaceutical Sciences (PhD)
Structure-function relationships of uridine diphosphate glucuronosyltransferases
Voltage gated potassium channels (Kv) belong to a larger family of proteins called ion channels. Kv channels occur ubiquitously in the body and play a range of essential roles in cellular processes such as signal propagation and cellular excitability. Kv are made up of four subunits, each of which is translated individually, followed by assembly and expression on the cell surface. Kv1.1 is a Kv family member capable of assembling as either a homotetramer or a heterotetramer. In particular, when Kv1.1 subunits assemble with other Kv1.x subunits, the former shape the activation threshold and kinetics of macroscopic current of a channel, and play an important role in the trafficking and surface expression of other Kv1.4 channels. Dysfunction of Kv1.1 has been linked to an autosomal dominant neurological disorder, episodic ataxia (EA-1), that affects both the central nervous system and peripheral nervous system. Patients with EA-1 are 10 times more likely to develop epilepsy than normal individuals. Kv1.1 channels have also been implicated in sudden unexpected death in epilepsy (SUDEP) and Alzheimer’s disease. Dysfunction of Kv1.1 channels has been characterized by studying specific mutations in KCNA1 genes. Current techniques for generating Kv1.1 channels in heterologous expression systems for subsequent biophysical characterizations include coexpression and dimer construction methods, and the creation of tandem dimer-linked concatemers. The latter provides the greatest control over stoichiometry and arrangement of subunits; however, generation of each concatemer is extremely labour- and time-intensive. This thesis focuses on the development of a new concatemer system built on an inhouse plasmid (pICDNA), with an intentionally designed linker sequence that physically concatenates four Kcna1 genes. The Kv1.1 homotetramer concatemer system has been developed to permit flexibility, such that each gene (or multiple genes) in the concatemer can be targets for future cloning. The development of the Kv1.1 homotetramer system will facilitate the examination of the role Kv1.1 channels play, independently of its main partners, Kv1.2 and Kv1.4. The Kv1.1 concatemer platform can be used in the future as a backbone upon which future Kv1.x heterotetramers can be developed more easily.