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Sec‐independent translocation of a 100‐residue periplasmic N‐terminal tail in the E. coli inner membrane protein proW.
Author(s) -
Whitley P.,
Zander T.,
Ehrmann M.,
Haardt M.,
Bremer E.,
Heijne G.
Publication year - 1994
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1994.tb06788.x
Subject(s) - periplasmic space , chromosomal translocation , biology , bacterial outer membrane , inner membrane , membrane , biophysics , residue (chemistry) , escherichia coli , signal peptide , microbiology and biotechnology , terminal (telecommunication) , membrane protein , biochemistry , peptide sequence , gene , computer science , telecommunications
The ProW protein, located in the inner membrane of Escherichia coli, has a very unusual topology with a 100‐residue‐long N‐terminal tail protruding into the periplasmic space. We have studied the mechanism of membrane translocation of the periplasmic tail by analysing ProW‐PhoA and ProW‐Lep fusion proteins, both in wild‐type cells and in cells with an impaired sec machinery. Our results show that the translocation efficiency is not affected by treatments that compromise the SecA and SecY functions, but that translocation is completely blocked by dissipation of the proton motive force or by the introduction of extra positively charged residues into the N‐terminal tail. This suggests that the sec machinery can act properly only on domains located on the C‐terminal side of a translocation signal, and that the N‐terminal tail is driven through the membrane by a mechanism that involves the proton motive force.