Crystal Structure of the Potassium Channel KirBac1.1 in the Closed State

TLDR

KirBac1.1 is a prokaryotic inward‑rectifier potassium channel. The closed‑state structure of KirBac1.1 at 3.65 Å reveals its activation gate and shows that gating couples intracellular and membrane domains, suggesting distinct entry points converge on a common mechanistic pathway.

Abstract

The KirBac1.1 channel belongs to the inward-rectifier family of potassium channels. Here we report the structure of the entire prokaryotic Kir channel assembly, in the closed state, refined to a resolution of 3.65 angstroms. We identify the main activation gate and structural elements involved in gating. On the basis of structural evidence presented here, we suggest that gating involves coupling between the intracellular and membrane domains. This further suggests that initiation of gating by membrane or intracellular signals represents different entry points to a common mechanistic pathway.