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PDBsum entry 5fxb
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Transport protein
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PDB id
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5fxb
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References listed in PDB file
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Key reference
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Title
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Crystal structures of a double-Barrelled fluoride ion channel.
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Authors
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R.B.Stockbridge,
L.Kolmakova-Partensky,
T.Shane,
A.Koide,
S.Koide,
C.Miller,
S.Newstead.
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Ref.
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Nature, 2015,
525,
548-551.
[DOI no: ]
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PubMed id
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DOI number
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Abstract
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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 Å. 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.
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