Publication Date:
2015-09-08
Description:
To contend with hazards posed by environmental fluoride, microorganisms export this anion through F(-)-specific ion channels of the Fluc family. Since the recent discovery of Fluc channels, numerous idiosyncratic features of these proteins have been unearthed, including strong selectivity for F(-) over Cl(-) and dual-topology dimeric assembly. To understand the chemical basis for F(-) permeation and how the antiparallel subunits convene to form a F(-)-selective pore, here we solve the crystal structures of two bacterial Fluc homologues in complex with three different monobody inhibitors, with and without F(-) present, to a maximum resolution of 2.1 A. The structures reveal a surprising 'double-barrelled' channel architecture in which two F(-) ion pathways span the membrane, and the dual-topology arrangement includes a centrally coordinated cation, most likely Na(+). F(-) selectivity is proposed to arise from the very narrow pores and an unusual anion coordination that exploits the quadrupolar edges of conserved phenylalanine rings.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stockbridge, Randy B -- Kolmakova-Partensky, Ludmila -- Shane, Tania -- Koide, Akiko -- Koide, Shohei -- Miller, Christopher -- Newstead, Simon -- 102890/Z/13/Z/Wellcome Trust/United Kingdom -- K99 GM111767/GM/NIGMS NIH HHS/ -- K99-GM-111767/GM/NIGMS NIH HHS/ -- R01 GM107023/GM/NIGMS NIH HHS/ -- R01-GM107023/GM/NIGMS NIH HHS/ -- U54 GM087519/GM/NIGMS NIH HHS/ -- U54-GM087519/GM/NIGMS NIH HHS/ -- England -- Nature. 2015 Sep 24;525(7570):548-51. doi: 10.1038/nature14981. Epub 2015 Sep 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02454, USA. ; Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, USA. ; Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QU, UK. ; Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26344196" target="_blank"〉PubMed〈/a〉
Keywords:
Anions/chemistry/metabolism/pharmacology
;
Bacterial Proteins/*chemistry/*metabolism
;
Cell Membrane/metabolism
;
Crystallography, X-Ray
;
Fluorides/chemistry/*metabolism/*pharmacology
;
Ion Channels/*chemistry/*metabolism
;
Models, Biological
;
Models, Molecular
;
Phenylalanine/metabolism
;
Protein Conformation
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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