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Article

Metal Binding Domains 3 and 4 of the Wilson Disease Protein: Solution Structure and Interaction with the Copper(I) Chaperone HAH1^†^‡

Supporting Info

Lucia Banci^§, Ivano Bertini*^§, Francesca Cantini^§, Amy C. Rosenzweig and Liliya A. Yatsunyk

Magnetic Resonance Center (CERM), University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy, Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy, and Department of Biochemistry, Molecular Biology, and Cell Biology and Department of Chemistry, Northwestern University, Evanston, Illinois 60208

Biochemistry, 2008, 47 (28), pp 7423–7429

DOI: 10.1021/bi8004736

Publication Date (Web): June 18, 2008

†

This work was supported by National Institutes of Health Grant GM58518, Integrated Project SPINE2-COMPLEXES n° 031220, UPMAN n° LSHG-CT-2004-512052, and Ente Cassa di Risparmio di Firenze.

‡

Resonance assignments and the atomic coordinates for the NMR structures of apo-WLN34 have been deposited in BioMagResBank (entry 11041) and Protein Data Bank, respectively (entry 2ROP).

University of Florence.

* To whom correspondence should be addressed: Magnetic Resonance Center, University of Florence, Via L. Sacconi, 6 50019 Sesto Fiorentino, Italy. Fax: +39 055 4574271. Telephone: +39 055 4574272. E-mail: ivanobertini@cerm.unifi.it.

Northwestern University.

Abstract

The Wilson disease protein or ATP7B is a P_1B-type ATPase involved in human copper homeostasis. The extended N-terminus of ATP7B protrudes into the cytosol and contains six Cu(I) binding domains. This report presents the NMR structure of the polypeptide consisting of soluble Cu(I) binding domains 3 and 4. The two domains exhibit ferredoxin-like folds, are linked by a flexible loop, and act independently of one another. Domains 3 and 4 tend to aggregate in a concentration-dependent manner involving nonspecific intermolecular interactions. Both domains can be loaded with Cu(I) when provided as an acetonitrile complex or by the chaperone HAH1. HAH1 forms a 70% complex with domain 4 that is in fast exchange with the free protein in solution. The ability of HAH1 to form a complex only with some domains of ATP7B is an interesting property of this class of proteins and may have a signaling role in the function of the ATPases.

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