Calcium is a ubiquitous second messenger in cells that plays a vital role in the control of cellular and physiological processes as diverse as cell division, memory and learning, fertilization and muscle contraction. Opening of the sarcoplasmic reticulum (SR) Ca2+-release channel, the ryanodine receptor (RyR), in response to mechanical or chemical stimuli via the dihydropyridine receptor (DHPR) is a crucial step in the process of muscle excitation-contraction coupling. I have determined the first high-resolution structure of a folded domain of RyR1 (RyR1A). The structure adopts a β-trefoil fold that is similar to the homologous suppressor domain of the inositol 1,4,5-trisphosphate receptor (IP3R). I identified a loop region in RyR1A concentrated with malignant hyperthermia (MH)- and central core disease (CCD)-associated mutations that have been implicated in perturbing inter-domain interactions with downstream regions of RyR. More recently I have used nuclear magnetic resonance (NMR) spectroscopy to study the structure and dynamics of the cardiac isoform (RyR2) A domain and its mutants. I detected a dynamic α-helix that undergoes an α-helix to β-strand switch in the catecholaminergic polymorphic ventricular tachycardia (CPVT)-associated mutant, RyR2A Δ exon 3. This dynamic helix is localized at an interface with electron dense columns in the cryo-EM map of the tetrameric receptor that connect with the pore region, suggesting that this dynamic helix may also interact with downstream regions of RyR to gate the channel. My high-resolution structural studies in collaboration with others have shed light on the structural underpinnings of RyR function and dysfunction in human disease.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/43519 |
| Date | 08 January 2014 |
| Creators | Amador, Fernando |
| Contributors | Ikura, Mitsu |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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