title: A new ABC transporter mediating the detachment of lipid-modified proteins from membranes.
abstract: Lipoproteins in Escherichia coli are anchored to the periplasmic side of either the inner or the outer membrane by a lipid moiety that is covalently attached to the amino-terminal cysteine residue. Membrane specificity depends on a sorting signal at position 2 of the lipoprotein. Lipoproteins directed to the outer membrane are released from the inner membrane in an ATP-dependent manner through the formation of a complex with LolA, a periplasmic chaperone. However, the ATPase involved in this reaction has not been identified. Here we show, using reconstituted proteoliposomes, that a new complex, LolCDE, belonging to the ATP-binding cassette (ABC) transporter family, catalyses the release of lipoproteins in LolA- and sorting-signal-dependent manners. The LolCDE complex differs mechanistically from all other ABC transporters as it is not involved in the transmembrane transport of substrates. This new mechanism is evolutionarily conserved in other gram-negative bacteria.
authors.affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yakushi
authors.forename: K
authors.initials: K
authors.lastname: Masuda
authors.forename: S
authors.initials: S
authors.lastname: Narita
authors.forename: S
authors.initials: S
authors.lastname: Matsuyama
authors.forename: H
authors.initials: H
authors.lastname: Tokuda
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D015870:Gene Expression / Q000502:physiology; D008051:Lipid Bilayers / Q000378:metabolism; D008074:Lipoproteins / Q000378:metabolism*; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000502:physiology; D010957:Plasmids; D017386:Sequence Homology, Amino Acid
chemical_list: D018528:ATP-Binding Cassette Transporters; D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D008051:Lipid Bilayers; D008074:Lipoproteins; D008081:Liposomes; C407982:LolC protein, E coli; C407983:LolD protein, E coli; C407984:LolE protein, E coli