1. Structural Biology and Molecular Biophysics
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Mechanistic signs of double-barreled structure in a fluoride ion channel

  1. Nicholas B Last
  2. Ludmila Kolmakova-Partensky
  3. Tania Shane
  4. Christopher Miller  Is a corresponding author
  1. Howard Hughes Medical Institute, Brandeis University, United States
Research Article
  • Cited 23
  • Views 1,700
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Cite this article as: eLife 2016;5:e18767 doi: 10.7554/eLife.18767

Abstract

The Fluc family of F- ion channels protects prokaryotes and lower eukaryotes from the toxicity of environmental F-. In bacteria, these channels are built as dual-topology dimers whereby the two subunits assemble in antiparallel transmembrane orientation. Recent crystal structures suggested that Fluc channels contain two separate ion-conduction pathways, each with two F- binding sites, but no functional correlates of this unusual architecture have been reported. Experiments here fill this gap by examining the consequences of mutating two conserved F--coordinating phenylalanine residues. Substitution of each phenylalanine specifically extinguishes its associated F- binding site in crystal structures and concomitantly inhibits F- permeation. Functional analysis of concatemeric channels, which permit mutagenic manipulation of individual pores, show that each pore can be separately inactivated without blocking F- conduction through its symmetry-related twin. The results strongly support dual-pathway architecture of Fluc channels.

Article and author information

Author details

  1. Nicholas B Last

    Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Ludmila Kolmakova-Partensky

    Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Tania Shane

    Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Christopher Miller

    Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, United States
    For correspondence
    cmiller@brandeis.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-0273-8653

Funding

Howard Hughes Medical Institute (N/A)

  • Ludmila Kolmakova-Partensky

National Institute of General Medical Sciences (RO1-GM107023)

  • Ludmila Kolmakova-Partensky

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Kenton J Swartz, National Institutes of Health, United States

Publication history

  1. Received: June 14, 2016
  2. Accepted: July 22, 2016
  3. Accepted Manuscript published: July 23, 2016 (version 1)
  4. Version of Record published: August 1, 2016 (version 2)

Copyright

© 2016, Last et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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