Solution structure of the N-domain of Wilson disease protein: distinct nucleotide-binding environment and effects of disease mutations.
Wilson disease protein (ATP7B) is a copper-transporting P(1B)-type ATPase that regulates copper homeostasis and biosynthesis of copper-containing enzymes in human tissues. Inactivation of ATP7B or related ATP7A leads to severe neurodegenerative disorders, whereas their overexpression contributes to cancer cell resistance to chemotherapeutics. Copper-transporting ATPases differ from other P-type ATPases in their topology and the sequence of their nucleotide-binding domain (N-domain). To gain insight into the structural basis of ATP7B function, we have solved the structure of the ATP7B N-domain in the presence of ATP by using heteronuclear multidimensional NMR spectroscopy. The N-domain consists of a six-stranded beta-sheet with two adjacent alpha-helical hairpins and, unexpectedly, shows higher similarity to the bacterial K(+)-transporting ATPase KdpB than to the mammalian Ca(2+)-ATPase or Na(+),K(+)-ATPase. The common core structure of P-type ATPases is retained in the 3D fold of the N-domain; however, the nucleotide coordination environment of ATP7B within this fold is different. The residues H1069, G1099, G1101, I1102, G1149, and N1150 conserved in the P(1B)-ATPase subfamily contribute to ATP binding. Analysis of the frequent disease mutation H1069Q demonstrates that this mutation does not significantly affect the structure of the N-domain but prevents tight binding of ATP. The structure of the N-domain accounts for the disruptive effects of >30 known Wilson disease mutations. The unique features of the N-domain provide a structural basis for the development of specific inhibitors and regulators of ATP7B.
Dmitriev
Oleg
O
Department of Biomolecular Chemistry, University of Wisconsin, Madison, WI 53706, USA. dmitriev@usask.ca
Tsivkovskii
Ruslan
R
Abildgaard
Frits
F
Morgan
Clinton T
CT
Markley
John L
JL
Lutsenko
Svetlana
S
D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D027682:Cation Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D000073840:Copper-Transporting ATPases; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
D027682:Cation Transport Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C000612464:ATP7B protein, human; D000073840:Copper-Transporting ATPases