Figure 3.
A site located at the S4/pore interface is important for the effect of Wu50 on the WT Shaker KV channel.(A) Side view of the S4/pore site for the WT Shaker KV channel in the absence of resin-acid derivative. A POPC molecule is occupying the binding pocket. POPC is displayed using a CPK representation, each atom type colored differently (black: C; red: O; blue: N; brown: P; hydrogens are omitted for clarity). Important interacting residues are represented as sticks (shades of green: aromatic residues, shades of pink: positively charged residues). (B) Top view of a representative snapshot of the interaction between Wu50 and the S4/pore site in the WT Shaker KV channel. The channel is shown as gray ribbons, the Wu50 compounds are displayed using a space-filling representation, each atom type colored differently (black: C or Cl; red: O). Residues’ Cα coming in contact with Wu50 in at least one of the channel’s subunits (SUs) during MD simulations are represented as spheres and colored according to the subunit they belong to. (C) Zoomed-in side view of the S4/pore site for the WT Shaker KV channel in the presence of the resin-acid derivative Wu50. Wu50 is displayed using a CPK representation, each atom type colored differently (black: C; red: O). The rest of the representation is the same as in A. (D) Zoomed-in side view of the deeper S4/pore site for the W454A/R362Q mutant channel in the presence of the resin-acid derivative Wu50. (E–G) Representative normalized G(V) curves for Wu50-induced effects on different Shaker KV–channel mutants. 100 µM, pH = 9. (H) Wu50-induced G(V) shifts for different Shaker KV–channel mutants. 100 µM, pH = 9. Mean ± SEM (n = 3–6). ****, P < 0.0001. (I) Scheme of putative state-dependent interactions between Wu50 in the S4/pore site in the WT and the various mutants investigated. The endogenous gating charge arginines (R362 [=R1], R365 [=R2]) are denoted by filled blue circles, F416 and W454 by filled green (light and bright, respectively) circles. Mutations are denoted by empty circles. Mutation of W454 to Ala opens a deeper binding site in the vicinity of F416. Putative binding affinities for the site range from weak (white triangles) to medium (light purple triangle) to strong (dark purple triangle). Transitions between states are represented by arrows. Relative stabilization of a state through binding of the compound to this site leads to increased transitions to this state. Stabilization by medium binding increases the transition slightly (medium-size arrow), and stabilization by strong binding increases the transition greatly (large-size arrow). A reduction in transition probability is marked by a smaller arrow. The overall G(V) shift is due to the stabilization of open states (O and O+) relative to closed states (C1 and other closed states not represented here).

A site located at the S4/pore interface is important for the effect of Wu50 on the WT Shaker KV channel. (A) Side view of the S4/pore site for the WT Shaker KV channel in the absence of resin-acid derivative. A POPC molecule is occupying the binding pocket. POPC is displayed using a CPK representation, each atom type colored differently (black: C; red: O; blue: N; brown: P; hydrogens are omitted for clarity). Important interacting residues are represented as sticks (shades of green: aromatic residues, shades of pink: positively charged residues). (B) Top view of a representative snapshot of the interaction between Wu50 and the S4/pore site in the WT Shaker KV channel. The channel is shown as gray ribbons, the Wu50 compounds are displayed using a space-filling representation, each atom type colored differently (black: C or Cl; red: O). Residues’ Cα coming in contact with Wu50 in at least one of the channel’s subunits (SUs) during MD simulations are represented as spheres and colored according to the subunit they belong to. (C) Zoomed-in side view of the S4/pore site for the WT Shaker KV channel in the presence of the resin-acid derivative Wu50. Wu50 is displayed using a CPK representation, each atom type colored differently (black: C; red: O). The rest of the representation is the same as in A. (D) Zoomed-in side view of the deeper S4/pore site for the W454A/R362Q mutant channel in the presence of the resin-acid derivative Wu50. (E–G) Representative normalized G(V) curves for Wu50-induced effects on different Shaker KV–channel mutants. 100 µM, pH = 9. (H) Wu50-induced G(V) shifts for different Shaker KV–channel mutants. 100 µM, pH = 9. Mean ± SEM (n = 3–6). ****, P < 0.0001. (I) Scheme of putative state-dependent interactions between Wu50 in the S4/pore site in the WT and the various mutants investigated. The endogenous gating charge arginines (R362 [=R1], R365 [=R2]) are denoted by filled blue circles, F416 and W454 by filled green (light and bright, respectively) circles. Mutations are denoted by empty circles. Mutation of W454 to Ala opens a deeper binding site in the vicinity of F416. Putative binding affinities for the site range from weak (white triangles) to medium (light purple triangle) to strong (dark purple triangle). Transitions between states are represented by arrows. Relative stabilization of a state through binding of the compound to this site leads to increased transitions to this state. Stabilization by medium binding increases the transition slightly (medium-size arrow), and stabilization by strong binding increases the transition greatly (large-size arrow). A reduction in transition probability is marked by a smaller arrow. The overall G(V) shift is due to the stabilization of open states (O and O+) relative to closed states (C1 and other closed states not represented here).

This Feature Is Available To Subscribers Only

or Create an Account

Close Modal
Close Modal