Diverse Roles of the Metal Binding Domains and Transport Mechanism of Copper Transporting P-type ATPases

Copper transporting P-type (P 1B-1 -) ATPases are essential for cellular homeostasis. Nonetheless, the E1-E1P-E2P-E2 states mechanism of P 1B-1 -ATPases remains poorly understood. In particular, the role of the intrinsic metal binding domains (MBDs) is enigmatic. Here, four cryo-EM structures and molecular dynamics simulations of a P 1B-1 -ATPase are combined to reveal that in many eukaryotes the MBD immediately prior to the ATPase core, MBD −1 , serves a structural role, remodeling the ion-uptake region. In contrast, the MBD prior to MBD −1 , MBD −2 , likely assists in copper delivery to the ATPase core. Invariant Tyr, Asn and Ser residues in the transmembrane domain assist in positioning sulfur-providing copper-binding amino acids, allowing for copper uptake, binding and release. As such, our findings unify previously conflicting data on the transport and regulation of P 1B-1 -ATPases. The results are critical for a fundamental understanding of cellular copper homeostasis and for comprehension of the molecular bases of P 1B-1 -disorders and ongoing clinical trials.