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J Mol Biol. 2015 Jan 16;427(1):121-30. doi: 10.1016/j.jmb.2014.07.030. Epub 2014 Aug 12.

Hydrophobic gating in ion channels.

Author information

1
Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK; Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 2JD, UK.
2
Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 2JD, UK. Electronic address: mark.sansom@bioch.ox.ac.uk.
3
Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK; OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 2JD, UK. Electronic address: stephen.tucker@physics.ox.ac.uk.

Abstract

Biological ion channels are nanoscale transmembrane pores. When water and ions are enclosed within the narrow confines of a sub-nanometer hydrophobic pore, they exhibit behavior not evident from macroscopic descriptions. At this nanoscopic level, the unfavorable interaction between the lining of a hydrophobic pore and water may lead to stochastic liquid-vapor transitions. These transient vapor states are "dewetted", i.e. effectively devoid of water molecules within all or part of the pore, thus leading to an energetic barrier to ion conduction. This process, termed "hydrophobic gating", was first observed in molecular dynamics simulations of model nanopores, where the principles underlying hydrophobic gating (i.e., changes in diameter, polarity, or transmembrane voltage) have now been extensively validated. Computational, structural, and functional studies now indicate that biological ion channels may also exploit hydrophobic gating to regulate ion flow within their pores. Here we review the evidence for this process and propose that this unusual behavior of water represents an increasingly important element in understanding the relationship between ion channel structure and function.

KEYWORDS:

K2P channel; hydrophobic gating; ion channel; nanopore; potassium channel

PMID:
25106689
PMCID:
PMC4817205
DOI:
10.1016/j.jmb.2014.07.030
[Indexed for MEDLINE]
Free PMC Article

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