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Novel mechanism of outer membrane targeting of proteins in Gram‐negative bacteria
Author(s) -
Ferrandez Yann,
Condemine Guy
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06366.x
Subject(s) - bacterial outer membrane , biology , twin arginine translocation pathway , signal peptide , outer membrane efflux proteins , protein sorting signals , membrane protein , signal peptidase , inner membrane , biochemistry , protein targeting , membrane , vesicle associated membrane protein 8 , peptide sequence , escherichia coli , bacteria , cytoplasm , integral membrane protein , microbiology and biotechnology , membrane transport protein , genetics , gene
Summary In Gram‐negative bacteria, all the proteins destined for the outer membrane are synthesized with a signal sequence that is cleaved, either by the signal peptidase LepB for integral outer membrane proteins or by LspA for lipoproteins, when they cross the cytoplasmic membrane. The Dickeya dadantii protein PnlH does not possess a cleavable signal sequence but is anchored in the outer membrane by an N‐terminal targeting signal. Addition of the 41 N‐terminal amino acids of PnlH is sufficient for anchoring various hybrid proteins in the outer membrane. This targeting signal presents some of the characteristics of a Tat (twin arginine translocation) signal sequence but without an obvious cleavage site. We found that the Tat translocation pathway is required for the targeting process. This new mechanism of outer membrane protein targeting is probably widespread as PnlH was also addressed to the outer membrane when expressed in Escherichia coli . As PnlH was not detected as a substrate by Tat signal sequence prediction programmes, this would suggest that there may be many other unknown Tat‐dependent outer membrane proteins.