Dynamics of the metal-binding domains in the regulation of the Wilson disease protein, ATP7B
Date
2021-01-15
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
The Wilson disease protein, ATP7B, is a human copper transporter of the P-type ATPase
class that is required for maintaining copper homeostasis in the body. ATP7B contains six metal
binding domains that possess a ferredoxin-like βαββαβ-fold. Each metal binding domain (MBD)
has one copper-binding site characterized by a CxxC motif and each is connected to the next by
a flexible linker. MBD1-3 associate through transient interactions, as do MBD5-6. MBD1-3
transitions from a closed conformation to an open conformation upon receiving copper from the
copper chaperone ATOX1. Enzymatic activity and intracellular trafficking of ATP7B are
governed by the dynamics of the first three cytosolic MBDs. In our study, we used SAXS
analysis and model calculation to determine the copper-dependent change in conformational
space and MBD arrangement of the MBD1-6 chain. We have also used SAXS and model
calculation to determine that residue K269 of MBD3 as essential for proper domain arrangement
of the MBD1-3 fragment and its copper-dependent dynamics. We have shown that the compound
DC_AC50 (3-amino-N-(2-bromo-4,6-difluorophenyl)-6,7-dihydro-5H-cyclopenta[b]thieno[3,2-
e]pyridine-2-carboxamide) is able to bind to MBD1, MBD2, and MBD3. We used molecular
docking to identify DC_AC50 as a useful tool to study the copper transport activity and
localization of ATP7B. Lastly, we have demonstrated that the molecular basis of Wilson disease
caused by the G85V mutation is likely MBD1 misfolding causing ATP7B degradation in the cell.
Description
Keywords
ATP7B, copper transporters, protein structure
Citation
Degree
Master of Science (M.Sc.)
Department
Biochemistry
Program
Biochemistry