Critical role of a conserved transmembrane lysine in substrate recognition by the proton-coupled oligopeptide transporter YjdL.
Int J Biochem Cell Biol
; 55: 311-7, 2014 Oct.
Article
em En
| MEDLINE
| ID: mdl-25261786
ABSTRACT
Proton-coupled oligopeptide transporters (POTs) utilize an electrochemical proton gradient to accumulate peptides in the cytoplasm. Changing the highly conserved active-site Lys117 in the Escherichia coli POT YjdL to glutamine resulted in loss of ligand affinity as well as inability to distinguish between a dipeptide ligand and the corresponding dipeptide amide. The radically changed pH(Bulk) profiles of Lys117Gln and Lys117Arg mutants indicate an important role of Lys117 in facilitating protonation of the transporter; a notion that is supported by the close proximity of Lys117 to the conserved ExxERFxYY POT motif previously shown to be involved in proton translocation. These results point toward a novel dual role of Lys117 in direct or indirect interaction with both proton and peptide.
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MEDLINE
Assunto principal:
Oligopeptídeos
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Proteínas de Membrana Transportadoras
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Prótons
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Proteínas de Escherichia coli
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Lisina
Idioma:
En
Revista:
Int J Biochem Cell Biol
Ano de publicação:
2014
Tipo de documento:
Article