Direct identification of the site of binding on the chaperone SecB for the amino terminus of the translocon motor SecA.

ABSTRACT: Protein export mediated by the general secretory Sec system in Escherichia coli proceeds by a dynamic transfer of a precursor polypeptide from the chaperone SecB to the SecA ATPase motor of the translocon and subsequently into and through the channel of the membrane-embedded SecYEG heterotrimer. The complex between SecA and SecB is stabilized by several separate sites of contact. Here we have demonstrated directly an interaction between the N-terminal residues 2 through 11 of SecA and the C-terminal 13 residues of SecB by isothermal titration calorimetry and analytical sedimentation velocity centrifugation. We discuss the unusual binding properties of SecA and SecB in context of a model for transfer of the precursor along the pathway of export.

SUBMITTER: Randall LL 

PROVIDER: S-EPMC2895241 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature