Functional properties of the copper-transporting ATPase ATP7B (the Wilson's disease protein) expressed in insect cells

Ruslan Tsivkovskii, John F. Eisses, Jack H. Kaplan, Svetlana Lutsenko

Research output: Contribution to journalArticle

Abstract

Copper-transporting ATPase ATP7B is essential for normal distribution of copper in human cells. Mutations in the ATP7B gene lead to copper accumulation in a number of tissues and to a severe multisystem disorder, known as Wilson's disease. Primary sequence analysis suggests that the copper-transporting ATPase ATP7B or the Wilson's disease protein (WNDP) belongs to the large family of cation-transporting P-type ATPases, however, the detailed characterization of its enzymatic properties has been lacking. Here, we developed a baculovirus-mediated expression system for WNDP, which permits direct and quantitative analysis of catalytic properties of this protein. Using this system, we provide experimental evidence that WNDP has functional properties characteristic of a P-type ATPase. It forms a phosphorylated intermediate, which is sensitive to hydroxylamine, basic pH, and treatments with ATP or ADP. ATP stimulates phosphorylation with an apparent Km of 0.95 ± 0.25 μM; ADP promotes dephosphorylation with an apparent Km of 3.2 ± 0.7 μM. Replacement of Asp1027 with Ala in a conserved sequence motif DKTG abolishes phosphorylation in agreement with the proposed role of this residue as an acceptor of phosphate during the catalytic cycle. Catalytic phosphorylation of WNDP is inhibited by the copper chelator bathocuproine; copper reactivates the bathocuproine-treated WNDP in a specific and cooperative fashion confirming that copper is required for formation of the acylphosphate intermediate. These studies establish the key catalytic properties of the ATP7B copper-transporting ATPase and provide a foundation for quantitative analysis of its function in normal and diseased cells.

Original languageEnglish (US)
Pages (from-to)976-983
Number of pages8
JournalJournal of Biological Chemistry
Volume277
Issue number2
DOIs
StatePublished - Jan 11 2002
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Functional properties of the copper-transporting ATPase ATP7B (the Wilson's disease protein) expressed in insect cells'. Together they form a unique fingerprint.

  • Cite this