Atomistic Mechanisms of Allosteric Dysfunction in Wilson Disease: How Local ATP7B Mutations Propagate to Global...

Wilson disease (WD) is a severe metabolic disorder caused by mutations in the copper-transporting ATPase ATP7B. The MBD5-6 tandem module serves as a critical regulatory hub for the protein, harboring several pathogenic missense mutations, including T587M, A595T, and R616Q within the MBD6 domain. However, the atomistic mechanisms by which these localized defects propagate across the MBD5-6 tandem module to disrupt interdomain organization remain unclear. In this study, we employed AlphaFold 3 to generate initial structures of the wild-type and variant ATP7B, followed by three independent 500 ns all-atom molecular dynamics (MD) simulations of the extracted apo MBD5-6 region. Our results reveal that these pathogenic mutations disrupt module-level structural stability through distinct microscopic physicochemical mechanisms. Specifically, T587 M triggers steric overpacking and abnormal rigidification; A595T induces hydrophobic core melting and water penetration; and R616Q abolishes critical electrostatic tethers. Crucially, we uncover a multiscale pathogenic mechanism, in which localized perturbations propagate via the flexible linker, allosterically disrupting the interdomain structural tethering to drive macroscopic conformational heterogeneity. This study delineates a multiscale pathway from local atomic defects to interdomain dysfunction within the apo MBD5-6 module and provides structural hypotheses for how these perturbations may affect the conformational regulation of full-length ATP7B.