Dmitriev Oleg, Tsivkovskii Ruslan, Abildgaard Frits, Morgan Clinton T, Markley John L, Lutsenko Svetlana
Department of Biomolecular Chemistry, University of Wisconsin, Madison, WI 53706, USA.
Proc Natl Acad Sci U S A. 2006 Apr 4;103(14):5302-7. doi: 10.1073/pnas.0507416103. Epub 2006 Mar 27.
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.
威尔逊病蛋白（ATP7B）是一种铜转运P（1B）型ATP酶，可调节人体组织中的铜稳态和含铜酶的生物合成。ATP7B或相关的ATP7A失活会导致严重的神经退行性疾病，而它们的过度表达则会导致癌细胞对化疗药物产生耐药性。铜转运ATP酶在拓扑结构和核苷酸结合结构域（N结构域）的序列上与其他P型ATP酶不同。为了深入了解ATP7B功能的结构基础，我们利用异核多维核磁共振光谱法解析了ATP存在下ATP7B N结构域的结构。N结构域由一个六链β折叠和两个相邻的α螺旋发夹组成，出乎意料的是，它与细菌钾转运ATP酶KdpB的相似性高于与哺乳动物钙ATP酶或钠钾ATP酶的相似性。P型ATP酶的共同核心结构保留在N结构域的三维折叠中；然而，在此折叠中ATP7B的核苷酸配位环境不同。P（1B）-ATP酶亚家族中保守的H1069、G1099、G1101、I1102、G1149和N1150残基有助于ATP结合。对常见疾病突变H1069Q的分析表明，该突变不会显著影响N结构域的结构，但会阻止ATP的紧密结合。N结构域的结构解释了30多种已知威尔逊病突变的破坏作用。N结构域的独特特征为开发ATP7B的特异性抑制剂和调节剂提供了结构基础。
