Copper binding leads to increased dynamics in the regulatory N-terminal domain of full-length human copper transporter ATP7B

Abstract

ATP7B is a human copper-transporting P1B-type ATPase that is involved in copper homeostasis and resistance to platinum drugs in cancer cells. ATP7B consists of a copper-transporting core and a regulatory N-terminal tail that contains six metal-binding domains (MBD1-6) connected by linker regions. The MBDs can bind copper, which changes the dynamics of the regulatory domain and activates the protein, but the underlying mechanism remains unknown. To identify possible copper-specific structural dynamics involved in transport regulation, we constructed a model of ATP7B spanning the N-terminal tail and core catalytic domains and performed molecular dynamics (MD) simulations with (holo) and without (apo) copper ions bound to the MBDs. In the holo protein, MBD2, MBD3 and MBD5 showed enhanced mobilities, which resulted in a more extended N-terminal regulatory region. The observed separation of MBD2 and MBD3 from the core protein supports a mechanism where copper binding activates the ATP7B protein by reducing interactions among MBD1-3 and between MBD1-3 and the core protein. Instead, an increased interaction between MBD5 and the core protein was observed that brought the copper-binding site of MBD5 closer to the high-affinity internal copper-binding site in the core protein. The simulation results assign specific, mechanistic roles to the metal-binding domains involved in ATP7B regulation that are testable in experimental settings.

Copper coordination states affect the flexibility of copper Metallochaperone Atox1: Insights from molecular dynamics simulations

“…The wealth of states seen in Figure 3 suggests that Atox1 can adopt multiple states in its low coordination states to interact with other Cu‐binding proteins to facilitate metal ion transport. Recent work has shown a connection between Cu(I) binding and flexibility of the human copper‐transporting protein ATP7B which interacts with Atox1 39 …”

“…Recent work has shown a connection between Cu(I) binding and flexibility of the human copper-transporting protein ATP7B which interacts with Atox1. 39…”