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标题：Crystal structure of full-length KcsA in its closed conformation
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作者：Serdar Uysal ; Valeria Vásquez ; Valentina Tereshko 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2009
卷号：106
期号：16
页码：6644-6649
DOI：10.1073/pnas.0810663106
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：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 {approx}70 A toward the cytoplasm. This bundle promotes a {approx}15{degrees} 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.