The molecular basis of K+ exclusion by the Escherichia coli ammonium channel AmtB.
J Biol Chem
; 288(20): 14080-14086, 2013 May 17.
Article
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| MEDLINE
| ID: mdl-23546877
ABSTRACT
Members of the Amt family of channels mediate the transport of ammonium. The form of ammonium, NH3 or NH4(+), carried by these proteins remains controversial, and the mechanism by which they select against K(+) ions is unclear. We describe here a set of Escherichia coli AmtB proteins carrying mutations at the conserved twin-histidine site within the conduction pore that have altered substrate specificity and now transport K(+). Subsequent work established that AmtB-mediated K(+) uptake occurred against a concentration gradient and was membrane potential-dependent. These findings indicate that the twin-histidine element serves as a filter to prevent K(+) conduction and strongly support the notion that Amt proteins transport cations (NH4(+) or, in mutant proteins, K(+)) rather than NH3 gas molecules through their conduction pores.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Potasio
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Proteínas de Escherichia coli
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Proteínas de Transporte de Catión
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Escherichia coli
Idioma:
En
Revista:
J Biol Chem
Año:
2013
Tipo del documento:
Article