ATP-induced conformational changes of the nucleotide-binding domain of Na,K-ATPase.
The Na,K-ATPase hydrolyzes ATP to drive the coupled extrusion and uptake of Na+ and K+ ions across the plasma membrane. Here, we report two high-resolution NMR structures of the 213-residue nucleotide-binding domain of rat alpha1 Na,K-ATPase, determined in the absence and the presence of ATP. The nucleotide binds in the anti conformation and shows a relative paucity of interactions with the protein, reflecting the low-affinity ATP-binding state. Binding of ATP induces substantial conformational changes in the binding pocket and in residues located in the hinge region connecting the N- and P-domains. Structural comparison with the Ca-ATPase stabilized by the inhibitor thapsigargin, E2(TG), and the model of the H-ATPase in the E1 form suggests that the observed changes may trigger the series of events necessary for the release of the K+ ions and/or disengagement of the A-domain, leading to the eventual transfer of the gamma-phosphate group to the invariant Asp369.
Hilge
Mark
M
Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands. hilge@nmr.kun.nl
Siegal
Gregg
G
Vuister
Geerten W
GW
Güntert
Peter
P
Gloor
Sergio M
SM
Abrahams
Jan Pieter
JP
D033962:Adaptor Protein Complex 2 / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000378:metabolism*; D011480:Protease Inhibitors / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D051381:Rats; D017386:Sequence Homology, Amino Acid; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019284:Thapsigargin / Q000737:chemistry / Q000378:metabolism
D033962:Adaptor Protein Complex 2; D009711:Nucleotides; D011480:Protease Inhibitors; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D000254:Sodium-Potassium-Exchanging ATPase