Abstract
Eukaryotic cyclic nucleotide-modulated channels perform their diverse physiological roles by opening and closing their pores to ions in response to cyclic nucleotide binding. We here present a structural model for the cyclic nucleotide-modulated potassium channel homolog from Mesorhizobium loti, MloK1, determined from 2D crystals in the presence of lipids. Even though crystals diffract electrons to only ∼10 Å, using cryoelectron microscopy (cryo-EM) and recently developed computational methods, we have determined a 3D map of full-length MloK1 in the presence of cyclic AMP (cAMP) at ∼4.5 Å isotropic 3D resolution. The structure provides a clear picture of the arrangement of the cyclic nucleotide-binding domains with respect to both the pore and the putative voltage sensor domains when cAMP is bound, and reveals a potential gating mechanism in the context of the lipid-embedded channel.
Keywords:
2D crystals; CNBD; MloK1; MlotiK1; cryoelectron microscopy; cytoplasmic domains; electron crystallography; membrane protein; potassium channel; voltage sensor.
Copyright © 2017 Elsevier Ltd. All rights reserved.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacterial Proteins / chemistry*
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism
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Binding Sites
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Caenorhabditis elegans Proteins / chemistry
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Caenorhabditis elegans Proteins / genetics
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Caenorhabditis elegans Proteins / metabolism
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Cloning, Molecular
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Cryoelectron Microscopy / methods
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Cyclic AMP / chemistry*
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Cyclic AMP / metabolism
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Escherichia coli / genetics
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Escherichia coli / metabolism
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Gene Expression
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Genetic Vectors / chemistry
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Genetic Vectors / metabolism
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Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / chemistry
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Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / genetics
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Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / metabolism
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Image Processing, Computer-Assisted / methods
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Ion Channel Gating
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Ion Channels / chemistry
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Ion Channels / genetics
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Ion Channels / metabolism
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Lipid Bilayers / chemistry*
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Lipid Bilayers / metabolism
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Mesorhizobium / chemistry*
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Mesorhizobium / metabolism
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Models, Molecular
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Potassium / chemistry*
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Potassium / metabolism
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Potassium Channels / chemistry
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Potassium Channels / genetics
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Potassium Channels / metabolism
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Potassium Channels, Voltage-Gated / chemistry*
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Potassium Channels, Voltage-Gated / genetics
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Potassium Channels, Voltage-Gated / metabolism
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Protein Binding
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Protein Conformation, alpha-Helical
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Protein Conformation, beta-Strand
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Protein Interaction Domains and Motifs
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Protein Multimerization
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Structural Homology, Protein
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Thermodynamics
Substances
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Bacterial Proteins
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Caenorhabditis elegans Proteins
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HCN1 protein, human
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Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
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Ion Channels
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Lipid Bilayers
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Potassium Channels
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Potassium Channels, Voltage-Gated
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Recombinant Proteins
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tax-4 protein, C elegans
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Cyclic AMP
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Potassium