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Crystal structure of full-length KcsA in its closed conformation.

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 A, as well as that of its isolated C-terminal domain at 2.6 A. The structure of the full-length KcsA-Fab complex reveals a well-defined, 4-helix bundle that projects approximately 70 A toward the cytoplasm. This bundle promotes a approximately 15 degree 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.

SUBMITTER: Uysal S

PROVIDER: S-EPMC2672561 | biostudies-literature | 2009 Apr

REPOSITORIES: biostudies-literature

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Crystal structure of full-length KcsA in its closed conformation.

Uysal Serdar S Vásquez Valeria V Tereshko Valentina V Esaki Kaori K Fellouse Frederic A FA Sidhu Sachdev S SS Koide Shohei S Perozo Eduardo E Kossiakoff Anthony A

Proceedings of the National Academy of Sciences of the United States of America 20090403 16

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 A, as well as that of its isolated C-terminal domain at 2.6 A. The structure of the full-length KcsA-Fab complex reveals a well-defined, 4-helix bundle that projects approximately 70 A toward the cytoplasm. This bundle ...[more]

PMID: 19346472

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