Tandem function of nucleotide binding domains confers competence to sulfonylurea receptor in gating ATP-sensitive K+ channels. J Biol Chem 2002 Apr 19;277(16):14206-10
Date
02/05/2002Pubmed ID
11825892DOI
10.1074/jbc.M109452200Scopus ID
2-s2.0-0037134527 (requires institutional sign-in at Scopus site) 75 CitationsAbstract
Fundamental to the metabolic sensor function of ATP-sensitive K(+) (K(ATP)) channels is the sulfonylurea receptor. This ATP-binding cassette protein, which contains nucleotide binding domains (NBD1 and NBD2) with conserved Walker motifs, regulates the ATP sensitivity of the pore-forming Kir6.2 subunit. Although NBD2 hydrolyzes ATP, a property essential in K(ATP) channel gating, the role of NBD1, which has limited catalytic activity, if at all, remains less understood. Here, we provide functional evidence that cooperative interaction, rather than the independent contribution of each NBD, is critical for K(ATP) channel regulation. Gating of cardiac K(ATP) channels by distinct conformations in the NBD2 ATPase cycle, induced by gamma-phosphate analogs, was disrupted by point mutation not only of the Walker motif in NBD2 but also in NBD1. Cooling membrane patches to decelerate the intrinsic ATPase activity counteracted ATP-induced K(ATP) channel inhibition, an effect that mimicked stabilization of the MgADP-bound posthydrolytic state at NBD2 by the gamma-phosphate analog orthovanadate. Temperature-induced channel activation was abolished by mutations that either prevent stabilization of MgADP at NBD2 or ATP at NBD1. These findings provide a paradigm of K(ATP) channel gating based on integration of both NBDs into a functional unit within the multimeric channel complex.
Author List
Zingman LV, Hodgson DM, Bienengraeber M, Karger AB, Kathmann EC, Alekseev AE, Terzic AMESH terms used to index this publication - Major topics in bold
ATP-Binding Cassette TransportersAdenosine Diphosphate
Adenosine Triphosphate
Amino Acid Motifs
Animals
COS Cells
Cell Membrane
Cricetinae
DNA
Dose-Response Relationship, Drug
Electrophysiology
Escherichia coli
Guinea Pigs
Models, Biological
Mutagenesis, Site-Directed
Myocardium
Point Mutation
Potassium Channels
Potassium Channels, Inwardly Rectifying
Protein Binding
Protein Conformation
Protein Structure, Tertiary
Receptors, Drug
Recombinant Proteins
Sulfonylurea Receptors
Time Factors
Transfection