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Cu(I) Controls Conformational States in Human Atox1 Metallochaperone: An EPR and Multiscale Simulation Study
journal contribution
posted on 2020-05-22, 22:03 authored by Ortal Perkal, Zena Qasem, Meital Turgeman, Renana Schwartz, Lada Gevorkyan-Airapetov, Matic Pavlin, Alessandra Magistrato, Dan Thomas Major, Sharon RuthsteinAtox1 is a human
copper metallochaperone that is responsible for
transferring copper ions from the main human copper transporter, hCtr1,
to ATP7A/B in the Golgi apparatus. Atox1 interacts with the Ctr1 C-terminal
domain as a dimer, although it transfers the copper ions to ATP7A/B
in a monomeric form. The copper binding site in the Atox1 dimer involves
Cys12 and Cys15, while Lys60 was also suggested to play a role in
the copper binding. We recently showed that Atox1 can adopt various
conformational states, depending on the interacting protein. In the
current study, we apply EPR experiments together with hybrid quantum
mechanics–molecular mechanics molecular dynamics simulations
using a recently developed semiempirical density functional theory
approach, to better understand the effect of Atox1’s conformational
states on copper coordination. We propose that the flexibility of
Atox1 occurs owing to protonation of one or more of the cysteine residues,
and that Cys15 is an important residue for Atox1 dimerization, while
Cys12 is a critical residue for Cu(I) binding. We also show that Lys60
electrostatically stabilizes the Cu(I)–Atox1 dimer.