Difference in stability of the N-domain underlies distinct intracellular properties of the E1064A and H1069Q mutants of copper-transporting ATPase ATP7B

Oleg Y. Dmitriev, Ashima Bhattacharjee, Sergiy Nokhrin, Eva Maria E. Uhlemann, Svetlana Lutsenko

Research output: Contribution to journalArticle

Abstract

Wilson disease (WD) is a disorder of copper metabolism caused by mutations in the Cu-transporting ATPase ATP7B. WD is characterized by significant phenotypic variability, the molecular basis of which is poorly understood. The E1064A mutation in the N-domain of ATP7B was previously shown to disrupt ATP binding. We have now determined, by NMR, the structure of the N-domain containing this mutation and compared properties of E1064A and H1069Q, another mutant with impaired ATP binding. The E1064A mutation does not change the overall fold of the N-domain. However, the position of the α1,α2- helical hairpin (α-HH) that houses Glu1064 and His 1069 is altered. The α-HH movement produces a more open structure compared with the wild-type ATP-bound form and misaligns ATP coordinating residues, thus explaining complete loss of ATP binding. In the cell, neither the stability nor targeting of ATP7B-E1064A to the trans-Golgi network differs significantly from the wild type. This is in a contrast to the H1069Q mutation within the same α-HH, which greatly destabilizes protein both in vitro and in cells. The difference between two mutants can be linked to a lower stability of the α-HH in the H1069Q variant at the physiological temperature. We conclude that the structural stability of the N-domain rather than the loss of ATP binding plays a defining role in the ability of ATP7B to reach the trans-Golgi network, thus contributing to phenotypic variability in WD.

Original languageEnglish (US)
Pages (from-to)16355-16362
Number of pages8
JournalJournal of Biological Chemistry
Volume286
Issue number18
DOIs
StatePublished - May 6 2011

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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