Structural organization and mechanisms of cooperativity in the N-Terminal domains of human CU-ATpases

Copper‑transporting ATPases ATP7A and ATP7B use six N‑terminal metal‑binding domains (MBDs) to sense cytosolic copper, but how these domains coordinate regulation is unclear. Using biochemical and computational methods, we show that ATP7B’s MBDs form a compact structure that undergoes major reorganization with copper binding or CxxC mutation. MBD2 appears to be the primary copper‑accepting site from ATOX1, with MBD4 and MBD6 acting downstream. ATP7B shows cooperative structural changes not observed in ATP7A, and disease‑associated mutations alter copper‑transfer behavior. These findings support a model in which inter‑MBD loops mediate copper‑dependent conformational signaling.