Probing Weak Copper Chaperone-Wilson Disease Protein Interactions At The Single-Molecule Level With Nanovesicle Trapping
Copper is an essential cofactor for many metalloproteins, yet it can also be cytotoxic, therefore, intracellular copper trafficking is tightly regulated. Copper delivery inside cells is mediated by copper chaperones, which bind and deliver copper to their target proteins, preventing adventitious chemical reactions with the metal. Various pathways for copper transport exist; of particular interest to this thesis is the pathway between the copper chaperone Hah1 and Wilson disease protein (WDP). Limited dynamic information is available on how the copper chaperone Hah1 and the metal binding domains (MBDs) of WDP interact for copper transfer. In this thesis, the interaction dynamics of Hah1 and a single MBD of WDP is investigated. Since these protein-protein interactions are relatively weak in nature, a nanovesicle trapping strategy is used to increase the effective concentration of single molecules (Chapter 2). Individual interaction events are then monitored by single-molecule Forster resonance energy transfer (smFRET). The interaction dynamics of Hah1 and the fourth MBD (MBD4) of WDP are initially studied in the absence of copper. The protein-protein interaction scheme and associated rate constants for the interaction process are extracted from the FRET efficiency (EFRET) and waiting-time distributions (Chapter 3). The EFRET distributions obtained from interactions in the absence and presence of copper are then used to gain insight on the underlying copper transfer process (Chapter 4).
dissertation or thesis