Structural basis for signal-sequence recognition by the translocase motor SecA as determined by NMR.
Cell
; 131(4): 756-69, 2007 Nov 16.
Article
em En
| MEDLINE
| ID: mdl-18022369
ABSTRACT
Recognition of signal sequences by cognate receptors controls the entry of virtually all proteins to export pathways. Despite its importance, this process remains poorly understood. Here, we present the solution structure of a signal peptide bound to SecA, the 204 kDa ATPase motor of the Sec translocase. Upon encounter, the signal peptide forms an alpha-helix that inserts into a flexible and elongated groove in SecA. The mode of binding is bimodal, with both hydrophobic and electrostatic interactions mediating recognition. The same groove is used by SecA to recognize a diverse set of signal sequences. Impairment of the signal-peptide binding to SecA results in significant translocation defects. The C-terminal tail of SecA occludes the groove and inhibits signal-peptide binding, but autoinhibition is relieved by the SecB chaperone. Finally, it is shown that SecA interconverts between two conformations in solution, suggesting a simple mechanism for polypeptide translocation.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Membrana Transportadoras
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Proteínas de Bactérias
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Sinais Direcionadores de Proteínas
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Estrutura Terciária de Proteína
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Estrutura Secundária de Proteína
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Adenosina Trifosfatases
Idioma:
En
Revista:
Cell
Ano de publicação:
2007
Tipo de documento:
Article
País de afiliação:
Estados Unidos