Mechanistic signs of double-barreled structure in a fluoride ion channel
- Howard Hughes Medical Institute, Brandeis University, United States
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
Christopher Miller
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.
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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Mechanistic signs of double-barreled structure in a fluoride ion channel
eLife 5:e18767.
https://doi.org/10.7554/eLife.18767
