Year of Award

2023

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Chemistry

Department or School/College

Department of Chemistry and Biochemistry

Committee Chair

Klára Briknarová

Commitee Members

Bruce Bowler, Jesse Hay, Stephen Sprang, Kent Sugden

Keywords

fibronectin, protein biochemistry, structural biology, X-ray crystallography

Abstract

Fibronectin is an extracellular matrix glycoprotein that plays a major role in cell adhesion, cell growth and tissue organization. FN is comprised of three types of modular repeats – type I (FN1), type II (FN2), type III (FN3) – and a non-homologous variable region (V region) that can contain 0 to 120 amino acid residues depending on alternative splicing. Fibronectin contains several fibronectin type 3 (FN3) domains, which all have a β-sandwich structure composed of three-stranded (β-strands A, B and E) and fourstranded (β-strands C, D, F and G) β-sheets. FN3 domains are susceptible to mechanical unfolding, and it has been hypothesized that their unfolding leads to exposure of cryptic binding sites during fibrillogenesis. In this research, we investigated the structure and stability of the 11th FN3 domain of human fibronectin (11FN3) in the context of its neighboring FN3 domains using X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy and denaturant titration experiments. Our results show that amino acid residues and domains at the C-terminus affect the structure and stability of 11FN3. In addition to the study of 11FN3, we will also be describing here two ongoing projects aiming to determine the structure of intact, soluble fibronectin and the interdomain interactions necessary for fibril formation using cryo-electron tomography and optical tweezers. A complete understanding of the structure and conformation of full-length FN will provide a better molecular picture of the cellular matrix essential for various cellular processes.

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