UC Davis

Low complexity sequence protein domains harbor mutations correlated with neurodegenerative diseases, such as amyotrophic lateral sclerosis and frontal temporal dementia. One such protein is cytotoxic granule associated RNA binding protein TIA1 or simply TIA1, which is an important factor in the formation of fibril-like structures seen in disease, often with mutations within the sequence. This dissertation investigates the structural characteristics of the TIA1 low complexity (TIA1-LC) domain using primarily solid state nuclear magnetic resonance. Chapter 1 introduces the prominent role proteins play in human disease, and it provides a background in some of the efforts made in understanding the diseases in hopes of providing a basis for potential therapeutic treatments. Chapter 2 provides a detailed protocol for handling and preparing TIA1-LC domain fibrils for structural studies including the different fibril forming techniques. Chapter 3 contains a detailed structural characterization of the wild-type TIA1-LC fibrils and the aging of liquid droplets formed by the wild-type and a widely studied disease mutant, to help explain the formation of fibrillar aggregates in disease. Finally, Chapter 4 provides an initial structural characterization of TIA1-LC fibrils formed from seven disease mutations discovered in a clinical cohort of amyotrophic lateral sclerosis patients. Chapter 4 sheds light on the structural conformations accessible to the wild-type and TIA1-LC mutants. This dissertation provides a key contribution towards a more detailed characterization for understanding the molecular progression of disease pathology.