Structure of human Wilson protein domains 5 and 6 and their interplay with domain 4 and the copper chaperone HAH1 in copper uptake.
Human Wilson protein is a copper-transporting ATPase located in the secretory pathway possessing six N-terminal metal-binding domains. Here we focus on the function of the metal-binding domains closest to the vesicular portion of the copper pump, i.e., domain 4 (WLN4), and a construct of domains 5 and 6 (WLN5-6). For comparison purposes, some experiments were also performed with domain 2 (WLN2). The solution structure of apoWLN5-6 consists of two ferredoxin folds connected by a short linker, and (15)N relaxation rate measurements show that it behaves as a unit in solution. An NMR titration of apoWLN5-6 with the metallochaperone Cu(I)HAH1 reveals no complex formation and no copper exchange between the two proteins, whereas titration of Cu(I)HAH1 with WLN4 shows the formation of an adduct that is in fast exchange on the NMR time scale with the isolated protein species as confirmed by (15)N relaxation data. A similar interaction is also observed between Cu(I)HAH1 and WLN2; however, the relative amount of the adduct in the protein mixture is lower. An NMR titration of apoWLN5-6 with Cu(I)WLN4 shows copper transfer, first to WLN6 then to WLN5, without the formation of an adduct. Therefore, we suggest that WLN4 and WLN2 are two acceptors of Cu(I) from HAH1, which then somehow route copper to WLN5-6, before the ATP-driven transport of copper across the vesicular membrane.
Achila
David
D
Department of Chemistry, Western Michigan University, 1903 West Michigan Avenue, Kalamazoo, MI 49008-5413, USA.
Banci
Lucia
L
Bertini
Ivano
I
Bunce
Jennifer
J
Ciofi-Baffoni
Simone
S
Huffman
David L
DL
D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D001692:Biological Transport; D027682:Cation Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D000079922:Copper Transport Proteins; D000073840:Copper-Transporting ATPases; D006527:Hepatolenticular Degeneration / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D056511:Metallochaperones; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000378:metabolism*; D017433:Protein Structure, Secondary
C474500:ATOX1 protein, human; D027682:Cation Transport Proteins; D000079922:Copper Transport Proteins; D056511:Metallochaperones; D018832:Molecular Chaperones; D003300:Copper; D000251:Adenosine Triphosphatases; D000073840:Copper-Transporting ATPases