Abstract
ATP-sensitive K+ (KATP) channels consist of two types of subunits, KIR6.x that form the pore, and sulfonylurea receptors (SURs) that serve as regulatory subunits. SURs are ATP-binding cassette (ABC) proteins and contain, in addition to two nucleotide binding folds, the binding sites for channel openers such as diazoxide and P1075 and channel inhibitors such as glibenclamide (GBC) and repaglinide. Structurally, SURs differ from most eukaryotic ABC proteins by an additional amino-terminal transmembrane domain (TMD0); in case of SUR1, the subunit of the pancreatic KATP channel, TMD0 serves as a major domain for association with KIR. In this study we sought to elucidate the roles of TMD0 in SUR2B, the smooth muscle gating subunit, in the coupling between SUR2B and KIR6.2, in the self-association of SUR2B and in channel modulator binding to SUR2B. SUR2B has a weaker affinity for sulfonylureas thus SUR2BY1206S, with a higher affinity for GBC, but an equivalent opener binding was used. Association of SUR2BYSΔ, lacking TMD0, with KIR6.2 was shown by immunoprecipitation; however, no evidence for formation of functional channels was obtained. SUR2BYSΔ self-associates like SUR2BYS and binds GBC, repaglinide, and P1075 with slightly reduced affinities. The binding profile of the SUR2BYSΔ/KIR6.2 complex differs slightly but significantly from that of SUR2BYSΔ alone showing impaired allosteric coupling of binding sites. We conclude that TMD0 is not required for oligomerization of SUR2B, is of only minor importance in ligand binding, but is essential for both functional and allosteric coupling of SUR2B to KIR6.2.
Similar content being viewed by others
Abbreviations
- GBC:
-
Glibenclamide
- IP:
-
Immunoprecipitation
- KATP :
-
ATP-sensitive K+ channels
- KIR :
-
Inwardly rectifying K+ channel
- NBF:
-
Nucleotide binding fold
- P1075:
-
N-cyano-N′-(1,1-dimethylpropyl)-N″-3-pyridylguanidine
- SUR:
-
Sulfonylurea receptor
- TMD0:
-
Transmembrane domain 0
References
Aguilar-Bryan L, Nichols CG, Wechsler SW, Clement JP IV, Boyd AE III, Gonzáles G, Herrera-Soza H, Nguy K, Bryan J, Nelson DA (1995) Cloning of the β cell high-affinity sulfonylurea receptor: a regulator of insulin secretion. Science 268:423–426
Ashfield R, Gribble FM, Ashcroft SJH, Ashcroft FM (1999) Identification of the high-affinity tolbutamide site on the SUR1 subunit of the KATP channel. Diabetes 48:1341–1347
Babenko AP, Bryan J (2001) A conserved inhibitory and differential stimulatory action of nucleotides on KIR6.0/SUR complexes is essential for excitation-metabolism coupling by KATP channels. J Biol Chem 276:49083–49092
Babenko AP, Bryan J (2002) SUR-dependent modulation of KATP channels by an N-terminal KIR6.2 peptide. Defining intersubunit gating interactions. J Biol Chem 277:43997–44004
Babenko AP, Bryan J (2003) SUR domains that associate with and gate KATP pores define a novel gatekeeper. J Biol Chem 278:41577–41580
Babenko AP, Gonzales G, Bryan J (1999a) Two regions of sulfonylurea receptor specify the spontaneous bursting and ATP inhibition of KATP channel isoforms. J Biol Chem 274:11587–11592
Babenko AP, Gonzalez G, Bryan J (1999b) The tolbutamide site of SUR1 and a mechanism for its functional coupling to KATP channel closure. FEBS Lett 459:367–376
Bryan J, Crane A, Vila-Carriles WH, Babenko AP, Aguilar-Bryan L (2005) Insulin secretagogues, sulfonylurea receptors and KATP channels. Curr Pharm Des 11:2699–2716
Chan KW, Zhang H, Logothetis DE (2003) N-terminal transmembrane domain of the SUR controls trafficking and gating of Kir6 channel subunits. EMBO J 22:3833–3843
Cheng Y, Prusoff WH (1973) Relationship between the inhibition constant (Ki) and the concentration of inhibitor which causes 50% inhibition (IC50) of an enzymatic reaction. Biochem Pharmacol 22:3099–3108
Christopoulos A (1998) Assessing the distribution of parameters in models of ligand-receptor interaction: to log or not to log. Trends Pharmacol Sci 19:351–357
Clement JP IV, Kunjilwar K, Gonzalez G, Schwanstecher M, Panten U, Aguilar-Bryan L, Bryan J (1997) Association and stoichiometry of KATP channel subunits. Neuron 18:827–838
de Wet H, Mikhailov MV, Fotinou C, Dreger M, Craig TJ, Vénien-Bryan C, Ashcroft FM (2007) Studies of the ATPase activity of the ABC protein SUR1. FEBS J 274:3532–3544
D'hahan N, Jacquet H, Moreau C, Catty P, Vivaudou M (1999) A transmembrane domain of the sulfonylurea receptor mediates activation of ATP-sensitive K+ channels by K+ channel openers. Mol Pharmacol 56:308–315
Fang K, Csanády L, Chan KW (2006) The N-terminal transmembrane domain (TMD0) and a cytosolic linker (L0) of sulphonylurea receptor define the unique intrinsic gating of KATP channels. J Physiol 576:379–389
Gromada J, Dissing S, Kofod H, Frøkjaer-Jensen J (1995) Effects of the hypoglycaemic drugs repaglinide and glibenclamide on ATP-sensitive potassium-channels and cytosolic calcium levels in β TC3 cells and rat pancreatic beta cells. Diabetologia 38:1025–1032
Hambrock A, Löffler-Walz C, Kurachi Y, Quast U (1998) Mg2+ and ATP dependence of KATP channel modulator binding to the recombinant sulphonylurea receptor, SUR2B. Br J Pharmacol 125:577–583
Hambrock A, Löffler-Walz C, Russ U, Lange U, Quast U (2001) Characterization of a mutant sulfonylurea receptor SUR2B with high affinity for sulfonylureas and openers: differences in the coupling to Kir6.x subtypes. Mol Pharmacol 60:190–199
Hambrock A, Löffler-Walz C, Quast U (2002) Glibenclamide binding to sulphonylurea receptor subtypes: dependence on adenine nucleotides. Br J Pharmacol 136:995–1004
Harvey J, Hardy SC, Ashford MLJ (1999) Dual actions of the metabolic inhibitor, sodium azide on KATP channel currents in the rat CRI-G1 insulinoma cell line. Br J Pharmacol 126:51–60
Hough E, Mair L, Mackenzie W, Sivaprasadarao A (2002) Expression, purification, and evidence for the interaction of the two nucleotide-binding folds of the sulphonylurea receptor. Biochem Biophys Res Commun 294:191–197
Inagaki N, Gonoi T, Clement JP IV, Namba N, Inazawa J, Gonzalez G, Aguilar-Bryan L, Seino S, Bryan J (1995) Reconstitution of IKATP: an inward rectifier subunit plus the sulfonylurea receptor. Science 270:1166–1170
Isomoto S, Kondo C, Yamada M, Matsumoto S, Higashiguchi O, Horio Y, Matsuzawa Y, Kurachi Y (1996) A novel sulfonylurea receptor forms with BIR (KIR6.2) a smooth muscle type ATP-sensitive K+ channel. J Biol Chem 271:24321–24324
Kang G, Chepurny OG, Malester B, Rindler MJ, Rehmann H, Bos JL, Schwede F, Coetzee WA, Holz GG (2006) cAMP sensor Epac as a determinant of ATP-sensitive potassium channel activity in human pancreatic β cells and rat INS-1 cells. J Physiol 573:595–609
Locher KP (2009) Structure and mechanism of ATP-binding cassette transporters. Philos Trans R Soc Lond B Biol Sci 364:239–245
Löffler-Walz C, Hambrock A, Quast U (2002) Interaction of KATP channel modulators with sulfonylurea receptor SUR2B: implication for tetramer formation and allosteric coupling of subunits. Mol Pharmacol 61:407–414
Matsuo M, Kioka N, Amachi T, Ueda K (1999) ATP binding properties of the nucleotide-binding folds of SUR1. J Biol Chem 274:37479–37482
Mikhailov MV, Ashcroft SJH (2000) Interactions of the sulfonylurea receptor 1 subunit in the molecular assembly of β cell KATP channels. J Biol Chem 275:3360–3364
Mikhailov MV, Mikhailova EA, Ashcroft SJH (2001) Molecular structure of the glibenclamide binding site of the β-cell K-ATP channel. FEBS Lett 499:154–160
Mikhailov MV, Campbell JD, de Wet H, Shimomura K, Zadek B, Collins RF, Sansom MSP, Ford RC, Ashcroft FM (2005) 3-D structural and functional characterization of the purified KATP channel complex Kir6.2-SUR1. EMBO J 24:4166–4175
Moreau C, Jacquet H, Prost A-L, D'hahan N, Vivaudou M (2000) The molecular basis of the specificity of action of KATP channel openers. EMBO J 19:6644–6651
Oldham ML, Davidson AL, Chen J (2008) Structural insights into ABC transporter mechanism. Curr Opin Struct Biol 18:726–733
Rainbow RD, James M, Hudman D, Al Johi M, Singh H, Watson PJ, Ashmole I, Davies NW, Lodwick D, Norman RI (2004) Proximal C-terminal domain of sulphonylurea receptor 2A interacts with pore-forming Kir6 subunits in KATP channels. Biochem J 379:173–181
Rees DC, Johnson E, Lewinson O (2009) ABC transporters: the power to change. Nat Rev Mol Cell Biol 10:218–227
Russ U, Lange U, Löffler-Walz C, Hambrock A, Quast U (2003) Binding and effect of KATP channel openers in the absence of Mg2+. Br J Pharmacol 139:368–380
Schwanstecher M, Sieverding C, Dörschner H, Gross I, Aguilar-Bryan L, Schwanstecher C, Bryan J (1998) Potassium channel openers require ATP to bind to and act through sulfonylurea receptors. EMBO J 17:5529–5535
Seino S, Miki T (2003) Physiological and pathophysiological roles of ATP-sensitive K+ channels. Prog Biophys Mol Biol 81:133–176
Stephan D, Winkler M, Kühner P, Russ U, Quast U (2006) Selectivity of repaglinide and glibenclamide for the pancreatic over the cardiovascular KATP channels. Diabetologia 49:2039–2048
Takasuka T, Sakurai T, Goto K, Furuichi Y, Watanabe T (1994) Human endothelin receptor ETB. Amino acid sequence requirements for super stable complex formation with its ligand. J Biol Chem 269:7509–7513
Tucker SJ, Gribble FM, Zhao C, Trapp S, Ashcroft FM (1997) Truncation of Kir6.2 produces ATP-sensitive K+ channels in the absence of the sulphonylurea receptor. Nature 387:179–183
Turner DL, Weintraub H (1994) Expression of achaete-scute homolog 3 in Xenopus embryos converts ectodermal cells to a neural fate. Genes Dev 8:1434–1447
Uhde I, Toman A, Gross I, Schwanstecher C, Schwanstecher M (1999) Identification of the potassium channel opener site on sulfonylurea receptors. J Biol Chem 274:28079–28082
Vila-Carriles WH, Zhao G, Bryan J (2007) Defining a binding pocket for sulfonylureas in ATP-sensitive potassium channels. FASEB J 21:18–25
Winkler M, Stephan D, Bieger S, Kühner P, Wolff F, Quast U (2007) Testing the bipartite model of the sulfonylurea receptor binding site: binding of A-, B-, and A+B-site ligands. J Pharmacol Exp Ther 322:701–708
Zerangue N, Schwappach B, Jan YN, Jan LY (1999) A new ER trafficking signal regulates the subunit stoichiometry of plasma membrane KATP channels. Neuron 22:537–548
Acknowledgments
The authors would like to thank Profs. Y. Kurachi and Y. Horio (Osaka, Japan) for the murine clone of SUR2B. This work was supported by the Deutsche Forschungsgemeinschaft grant Qu100/4-1 (UQ), the Dr. Karl Kuhn-Stiftung (UR), and ADA Grant 1-10-BS21 (JB).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Winkler, M., Kühner, P., Russ, U. et al. Role of the amino-terminal transmembrane domain of sulfonylurea receptor SUR2B for coupling to KIR6.2, ligand binding, and oligomerization. Naunyn-Schmiedeberg's Arch Pharmacol 385, 287–298 (2012). https://doi.org/10.1007/s00210-011-0708-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00210-011-0708-9