Crystal structures of a double-barrelled fluoride ion channel.
Nature
; 525(7570): 548-51, 2015 Sep 24.
Article
en En
| MEDLINE
| ID: mdl-26344196
ABSTRACT
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.
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Proteínas Bacterianas
/
Fluoruros
/
Canales Iónicos
Idioma:
En
Revista:
Nature
Año:
2015
Tipo del documento:
Article
País de afiliación:
Estados Unidos