Ligand-specific opening of a gated-porin channel in the outer membrane of living bacteria.
Science
; 276(5316): 1261-4, 1997 May 23.
Article
em En
| MEDLINE
| ID: mdl-9157886
ABSTRACT
Ligand-gated membrane channels selectively facilitate the entry of iron into prokaryotic cells. The essential role of iron in metabolism makes its acquisition a determinant of bacterial pathogenesis and a target for therapeutic strategies. In Gram-negative bacteria, TonB-dependent outer membrane proteins form energized, gated pores that bind iron chelates (siderophores) and internalize them. The time-resolved operation of the Escherichia coli ferric enterobactin receptor FepA was observed in vivo with electron spin resonance spectroscopy by monitoring the mobility of covalently bound nitroxide spin labels. A ligand-binding surface loop of FepA, which normally closes its transmembrane channel, exhibited energy-dependent structural changes during iron and toxin (colicin) transport. These changes were not merely associated with ligand binding, but occurred during ligand uptake through the outer membrane bilayer. The results demonstrate by a physical method that gated-porin channels open and close during membrane transport in vivo.
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Coleções:
01-internacional
Temas:
Geral
Base de dados:
MEDLINE
Assunto principal:
Proteínas da Membrana Bacteriana Externa
/
Proteínas de Transporte
/
Ativação do Canal Iônico
/
Enterobactina
/
Porinas
/
Receptores de Superfície Celular
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Proteínas de Escherichia coli
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Escherichia coli
Idioma:
En
Revista:
Science
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Estados Unidos