The Structural Basis for the Binding of Repaglinide to the Pancreatic KATP Channel  Dian Ding, Mengmeng Wang, Jing-Xiang Wu, Yunlu Kang, Lei Chen  Cell Reports  Volume 27, Issue 6, Pages 1848-1857.e4 (May 2019) DOI: 10.1016/j.celrep.2019.04.050 Copyright © 2019 The Author(s) Terms and Conditions

Cell Reports 2019 27, 1848-1857.e4DOI: (10.1016/j.celrep.2019.04.050) Copyright © 2019 The Author(s) Terms and Conditions

Figure 1 Structure of the KATP Channel in Complex with ATPγS and Repaglinide (A) Cryo-EM density map of the KATP channel, viewed from the side. Approximate position of the lipid bilayer is indicated by gray bars. Kir6.2, SUR1 TMD0-L0 (transmembrane domain 0-loop 0) fragment, TMD1-NBD1 (nucleotide-binding domain1), TMD2-NBD2, ATPγS, RPG, and lipids are colored in cyan, pale green, pink, blue, red, purple, and yellow, respectively. For better visualization of the ligands and Kir6.2, SUR1 subunits in the front and back were removed and the protein density is shown in transparency. Residual detergent densities are omitted. (B) Bottom view of the KATP channel from the intracellular side. Ligands are shown in the same colors as described in (A). (C) Top view of the KATP channel from the extracellular side. See also Figures S1, S2, and S3 and Table S1. Cell Reports 2019 27, 1848-1857.e4DOI: (10.1016/j.celrep.2019.04.050) Copyright © 2019 The Author(s) Terms and Conditions

Figure 2 The RPG Binding Site in SUR1 (A) Close-up view of the RPG binding site. Density of RPG is shown in mesh. Transmembrane domain 1 (TMD1) and transmembrane domain 2 are colored in pink and blue, respectively. RPG and residues that interact with RPG are shown as sticks. (B) A top-down view of the RPG binding site. Density of putative digitonin is shown in orange. Cell Reports 2019 27, 1848-1857.e4DOI: (10.1016/j.celrep.2019.04.050) Copyright © 2019 The Author(s) Terms and Conditions

Figure 3 Interactions between RPG and the KATP Channel (A) Cartoon representation of the interactions between RPG and SUR1. Digitonin, transmembrane domain 1, and transmembrane domain 2 are represented as orange, pink, and blue ovals, respectively. Residues that are different between SUR1 and SUR2 were marked with red circles. The corresponding residues in SUR2 are shown in gray besides the circles. (B) Interactions between glibenclamide (GBM) and SUR1. Residues are colored the same as described in (A). (C) Inhibitory effect of glibenclamide and RPG on various KATP constructs, determined by inside-out patch. Currents after drug treatment were normalized to currents before drug application. Dashed lines represent the currents of wild-type SUR1+ Kir6.2. Data are shown as mean ± SE of three individual patches (∗p < 0.05, ∗∗p < 0.01 by two-side t test). See also Figures S4 and S5. Cell Reports 2019 27, 1848-1857.e4DOI: (10.1016/j.celrep.2019.04.050) Copyright © 2019 The Author(s) Terms and Conditions

Figure 4 Cryo-EM Density Map of the Mini SUR1 (A) Side view of the cryo-EM density of the mini SUR1 bound with RPG. SUR1 TMD1-NBD1, TMD2-NBD2, RPG, and KNtp are colored in pink, blue, purple and cyan, respectively. The masked region used for signal subtraction and focused refinement is shown as dashed lines. (B) The KNtp density is more prominent after focused refinement. (C) The cross-section of the transmembrane domain density at the position indicated by the dashed line in (B). See also Figures S6 and S7 and Table S1. Cell Reports 2019 27, 1848-1857.e4DOI: (10.1016/j.celrep.2019.04.050) Copyright © 2019 The Author(s) Terms and Conditions

Figure 5 RPG Might Block Mg-ADP-Induced Conformational Changes of SUR1 (A) Structural alignment of the transmembrane domains of the SUR1 is shown in bottom view. Structure of RPG-bound state is shown in color. Structure of Mg-ADP bound state (5YWD) is shown in gray. RPG is shown in ball. Red arrows denote the conformational changes from RPG bound state to Mg-ADP bound state. (B) The effect of RPG inhibition of Mg-ADP activation on the currents of the SUR1/Kir6.2-GSGSGS construct in the inside-out mode. Cell Reports 2019 27, 1848-1857.e4DOI: (10.1016/j.celrep.2019.04.050) Copyright © 2019 The Author(s) Terms and Conditions

Figure 6 ATP Binding Site in SUR1 (A) Kir6.2 subunit showing R50, the adjacent Kir6 subunit, and the SUR1 subunit are colored pink, cyan, and green, respectively. Cryo-EM density of the K205 side chain is shown. (B) Subunits are shown in the same colors described in (A). Cryo-EM density of the E203 side chain is shown, and the dashed line indicates the interaction between E203 and Q52. (C) ATP dose-response curves for KATP were measured by inside-out patch (n = 3 patches). Curves were fitted to the Hill equation (half maximal inhibitory concentration [IC50] = 32.7 ± 1.1 μM and 145.4 ± 1.0 μM for Kir6.2/SUR1 and Kir6.2/SUR1-K205A, respectively). Error bars represent the standard error. (D) ATP dose-response curves for KATP composed of SUR2A and Kir6.2. IC50 for Kir6.2/SUR2A and Kir6.2/SUR2-K203A were 30.9 ± 1.1 μM and 108.3 ± 1.1 μM, respectively. Error bars represent the standard error and n = 3. (E) Inhibitory effect of ATP and activating effect of Mg-ADP on the macroscopic currents of the SUR1-K205A/Kir6.2 construct in inside-out mode. (F) Sequence alignment of the ABLOS motif from Mesocricetus auratus SUR1, Homo sapiens SUR1, Homo sapiens SUR2, and Danio rerio SUR1. Identical amino acids are highlighted in orange. The position of K205 is marked with an asterisk above. Cell Reports 2019 27, 1848-1857.e4DOI: (10.1016/j.celrep.2019.04.050) Copyright © 2019 The Author(s) Terms and Conditions

Figure 7 Subunit-Subunit Interaction Interfaces (A) Interface between SUR1 and Kir6.2 on the extracellular side. Kir6.2 subunit, SUR1-TMD0, and lipids are in blue, green, and orange, respectively. (B) Top view of one SUR1 and Kir6.2 subunit pair. SUR1-TMD1 is colored in pink, and others are shown in the same colors described in (A). Cell Reports 2019 27, 1848-1857.e4DOI: (10.1016/j.celrep.2019.04.050) Copyright © 2019 The Author(s) Terms and Conditions