Coiled coils are a well-known protein structure prevalent in eukaryotic function, synthetic applications, and de novo protein design. Coiled-coil folding is often described using heptad repeat positions labeled abcdefg where a and d positions occupy the interface between the coils, e and g positions flank the interface, and the b, c, and f positions face the solvent-exposed surface. The a, d, e, and g positions have been extensively studied in the coiled-coil literature. There is a lack of investigation on the impact of the b, c, and f positions on coiled-coil folding. Chapter 1 is an introduction to the heptad repeat of coiled coils and the impact on folding of each heptad repeat position. In Chapter 2 we introduce a non-covalent interaction among the b, c, and f positions of a coiled-coil trimer that significantly enhances thermodynamic stability. We identify characteristics of the f-position residue (hydrogen bond donating ability and hydrophobicity) that lead to the greatest amount of stability. Chapter 3 introduces crystal structures and molecular dynamic simulations of the interaction to identify the mechanism of stabilization. Further thermodynamic studies find a key salt-bridge interaction between the b and c positions that are influenced by the f-position residue. Chapter 4 explores the impact of salt on the non-covalent interaction and determines that the interaction is sensitive to salt screening and is ionic in nature. It also explores more characteristics of the f-position amino acid, in particular the hydrogen bond donating component. In Chapter 5 we insert the solvent-exposed interaction into helix bundles of differing length and oligomeric state. We find that stability is not only dependent upon amino acid identity but also the length and stoichiometry of a coiled coil.
| Identifer | oai:union.ndltd.org:BGMYU2/oai:scholarsarchive.byu.edu:etd-11441 |
| Date | 22 June 2023 |
| Creators | Stern, Kimberlee Larsen |
| Publisher | BYU ScholarsArchive |
| Source Sets | Brigham Young University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | https://lib.byu.edu/about/copyright/ |
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