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Sorting of lipoproteins to the outer membrane of Gram‐negative bacteria
Author(s) -
Tokuda Hajime
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a41
Subject(s) - bacterial outer membrane , periplasmic space , lipoprotein , membrane , chemistry , biochemistry , atp binding cassette transporter , inner membrane , biophysics , microbiology and biotechnology , transporter , biology , cholesterol , escherichia coli , gene
The lipoprotein sorting from the inner to the outer membrane of E. coli requires five Lol proteins. A LolCDE complex, an ATP binding cassette transporter, catalyzes the release of lipoproteins. Asp at +2 of lipoproteins functions as a Lol avoidance signal and therefore makes lipoproteins specific to the inner membrane, while other residues direct lipoproteins to the outer membrane. LolA, a periplasmic chaperone, forms a water‐soluble complex with lipoproteins and transfers them to LolB, a receptor for the LolA‐lipoprotein complex. LolB then mediates the incorporation of lipoproteins into the outer membrane. LolCDE could be isolated with tightly associated substrates. Taking advantage of this liganded LolCDE, the detailed molecular events occurring at the initial stage of lipoprotein sorting were examined. LolA has a hydrophobic cavity, which is closed by anα‐helical lid. The lid of LolA has been speculated to undergo opening and closing upon binding and dissociation of lipoproteins, respectively. LolB is itself a lipoprotein anchored to the outer membrane but its membrane anchor was found to be dispensable. Leu at +68 was found to play a critical role in the incorporation of lipoproteins into outer membranes. It was also found that the lipoprotein‐sorting signals functioning in Pseudomonas aeruginosa differ from those functioning in E. coli even though five Lol proteins are conserved.