Key result
The crystal structure of full-length KcsA in complex with a synthetic Fab chaperone was determined at 3.8 Å resolution, revealing a 4-helix bundle that promotes bending in the inner bundle gate.
The determined crystal structure of full-length KcsA reveals a 4-helix bundle that likely represents the physiologically relevant closed conformation of the channel.
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Structural model of closed KcsA identified; leaves open physiological relevance in mammalian channels.
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.
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Uysal et al. (2009) studied KcsA potassium channel. Synthetic antigen-binding fragments (Fabs) was evaluated on Crystal structure determination. The crystal structure of full-length KcsA in complex with a synthetic Fab chaperone was determined at 3.8 Å resolution, revealing a 4-helix bundle that promotes bending in the inner bundle gate.
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