Role of the copper-binding domain in the copper transport function of ATP7B, the P-type ATPase defective in Wilson disease.
We have analyzed the functional effect of site-directed mutations and deletions in the copper-binding domain of ATP7B (the copper transporting P-type ATPase defective in Wilson disease) using a yeast complementation assay. We have shown that the sixth copper-binding motif alone is sufficient, but not essential, for normal ATP7B function. The N-terminal two or three copper-binding motifs alone are not sufficient for ATP7B function. The first two or three N-terminal motifs of the copper-binding domain are not equivalent to, and cannot replace, the C-terminal motifs when placed in the same sequence position with respect to the transmembrane channel. From our data, we propose that the copper-binding motifs closest to the channel are required for the copper-transport function of ATP7B. We propose that cooperative copper binding to the copper-binding domain of ATP7B is not critical for copper transport function, but that cooperative copper binding involving the N-terminal two or three copper-binding motifs may be involved in initiating copper-dependent intracellular trafficking. Our data also suggest a functional difference between the copper-binding domains of ATP7A and ATP7B.
Forbes
J R
JR
Department of Medical Genetics, University of Alberta, Edmonton, T6G 2H7 Alberta, Canada.
Hsi
G
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Cox
D W
DW
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins; D003300:Copper / Q000378:metabolism*; D000073840:Copper-Transporting ATPases; D005816:Genetic Complementation Test; D006527:Hepatolenticular Degeneration / Q000201:enzymology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D012441:Saccharomyces cerevisiae / Q000235:genetics
D002352:Carrier Proteins; D027682:Cation Transport Proteins; D003300:Copper; D000251:Adenosine Triphosphatases; D000073840:Copper-Transporting ATPases