A "push and slide" mechanism allows sequence-insensitive translocation of secretory proteins by the SecA ATPase.
Cell
; 157(6): 1416-1429, 2014 Jun 05.
Article
em En
| MEDLINE
| ID: mdl-24906156
ABSTRACT
In bacteria, most secretory proteins are translocated across the plasma membrane by the interplay of the SecA ATPase and the SecY channel. How SecA moves a broad range of polypeptide substrates is only poorly understood. Here we show that SecA moves polypeptides through the SecY channel by a "push and slide" mechanism. In its ATP-bound state, SecA interacts through a two-helix finger with a subset of amino acids in a substrate, pushing them into the channel. A polypeptide can also passively slide back and forth when SecA is in the predominant ADP-bound state or when SecA encounters a poorly interacting amino acid in its ATP-bound state. SecA performs multiple rounds of ATP hydrolysis before dissociating from SecY. The proposed push and slide mechanism is supported by a mathematical model and explains how SecA allows translocation of a wide range of polypeptides. This mechanism may also apply to hexameric polypeptide-translocating ATPases.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Membrana Transportadoras
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Proteínas de Bactérias
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Proteínas
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Adenosina Trifosfatases
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Proteínas de Escherichia coli
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Escherichia coli
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article