Solution Structures of the Actuator Domain of ATP7A and ATP7B, the Menkes and Wilson Disease Proteins

摘要

ATP7A and ATP7B are two human P1B-type ATPases that have a crucial role in maintainingncopper(I) homeostasis. Among the various domains of these enzymes, one, called the Actuator or A-domain,nhas a regulatory function and is required for the phosphatase step of the catalytic cycle (dephosphorylation ofnthe intermediate formed during ATP hydrolysis). Here we report the solution structures of the A-domain ofnboth proteins, solved by heteronuclear NMR spectroscopy and a characterization of the dynamics of thenA-domain of ATP7A. We observed that the catalytically important TGE loop protrudes from the structurenready for interaction with the phosphorilated site in the ATP-binding domain. The loop is rigid, suggestingnthat the catalytic step does not require substantial structural flexibility or rearrangements. The presentnstructures were useful to rationalize the molecular effects of disease-causing mutations. In particular, it can benconcluded that mutations occurring in the A-domain either destabilize the fold of the domain (such asnGly860Val in ATP7A) or affect the network of communication within the domain (such as Leu873Arg innATP7A) or with the other domains of the enzyme (such as Gly853Arg in ATP7A).