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Crystal structure of full-length KcsA in its closed conformation

By Serdar Uysal, Valeria Vásquez, Valentina Tereshko, Kaori Esaki, Frederic A. Fellouse, Sachdev S. Sidhu, Shohei Koide, Eduardo Perozo and Anthony Kossiakoff

Abstract

KcsA is a proton-activated, voltage-modulated K+ channel that has served as the archetype pore domain in the Kv channel superfamily. Here, we have used synthetic antigen-binding fragments (Fabs) as crystallographic chaperones to determine the structure of full-length KcsA at 3.8 Å, as well as that of its isolated C-terminal domain at 2.6 Å. The structure of the full-length KcsA–Fab complex reveals a well-defined, 4-helix bundle that projects ≈70 Å toward the cytoplasm. This bundle promotes a ≈15° bending in the inner bundle gate, tightening its diameter and shifting the narrowest point 2 turns of helix below. Functional analysis of the full-length KcsA–Fab complex suggests that the C-terminal bundle remains whole during gating. We suggest that this structure likely represents the physiologically relevant closed conformation of KcsA

Topics: Biological Sciences
Publisher: National Academy of Sciences
OAI identifier: oai:pubmedcentral.nih.gov:2672561
Provided by: PubMed Central
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