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Sorting of an integral outer membrane protein via the lipoprotein‐specific Lol pathway and a dedicated lipoprotein pilotin
Author(s) -
Collin Séverine,
Guilvout Ingrid,
Nickerson Nicholas N.,
Pugsley Anthony P.
Publication year - 2011
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.1365-2958.2011.07596.x
Subject(s) - periplasmic space , bacterial outer membrane , dodecameric protein , biology , membrane , inner membrane , lipoprotein , chaperone (clinical) , biochemistry , biophysics , microbiology and biotechnology , escherichia coli , gene , cholesterol , dna , medicine , pathology
Summary The lipoprotein PulS is a dedicated chaperone that is required to target the secretin PulD to the outer membrane in Klebsiella or Escherichia coli , and to protect it from proteolysis. Here, we present indirect evidence that PulD protomers do not assemble into the secretin dodecamer before they reach the outer membrane, and that PulS reaches the outer membrane in a soluble heterodimer with the general lipoprotein chaperone LolA. However, we could not find any direct evidence for PulD protomer association with the PulS–LolA heterodimer. Instead, in cells producing PulD and a permanently locked PulS–LolA dimer (in which LolA carries an R43L substitution that prevents lipoprotein transfer to LolB in the outer membrane), LolAR43L was found in the inner membrane, probably still associated with PulS bound to PulD that had been incorrectly targeted because of the LolAR43L substitution. It is speculated that PulD protomers normally cross the periplasm together with PulS bound to LolA but when the latter cannot be separated (due to the mutation in lolA ), the PulD protomers form dodecamers that insert into the inner membrane.