The Stable Interaction Between Signal Peptidase LepB of Escherichia coli and Nuclease Bacteriocins Promotes Toxin Entry into the Cytoplasm.

ABSTRACT: LepB is a key membrane component of the cellular secretion machinery, which releases secreted proteins into the periplasm by cleaving the inner membrane-bound leader. We showed that LepB is also an essential component of the machinery hijacked by the tRNase colicin D for its import. Here we demonstrate that this non-catalytic activity of LepB is to promote the association of the central domain of colicin D with the inner membrane before the FtsH-dependent proteolytic processing and translocation of the toxic tRNase domain into the cytoplasm. The novel structural role of LepB results in a stable interaction with colicin D, with a stoichiometry of 1:1 and a nanomolar Kd determined in vitro. LepB provides a chaperone-like function for the penetration of several nuclease-type bacteriocins into

SUBMITTER: Mora L 

PROVIDER: S-EPMC4692208 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature