title: A novel ligand bound ABC transporter, LolCDE, provides insights into the molecular mechanisms underlying membrane detachment of bacterial lipoproteins.
abstract: The LolCDE complex of Escherichia coli belongs to the ABC transporter superfamily and initiates the lipoprotein sorting to the outer membrane by catalysing their release from the inner membrane. LolC and/or LolE, membrane subunits, recognize lipoproteins anchored to the outer surface of the inner membrane, while LolD hydrolyses ATP on its inner surface. We report here that ligand-bound LolCDE can be purified from the inner membrane in the absence of ATP. Liganded LolCDE represents an intermediate of the release reaction and exhibits higher affinity for ATP than the unliganded form. ATP binding to LolD weakens the interaction between LolCDE and lipoproteins and causes their dissociation in a detergent solution, while lipoprotein release from membranes requires ATP hydrolysis. Liganded LolCDE thus reveals molecular events brought about through ATP binding and hydrolysis. LolCDE is the first example of an ABC transporter purified with tightly bound native substrates. A single molecule of lipoprotein is found to bind per molecule of the LolCDE complex.
authors.affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Ito
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kanamaru
authors.forename: Naohiro
authors.initials: N
authors.lastname: Taniguchi
authors.forename: Shigehiko
authors.initials: S
authors.lastname: Miyamoto
authors.forename: Hajime
authors.initials: H
authors.lastname: Tokuda
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D020816:Amino Acid Motifs / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism; D003902:Detergents; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008024:Ligands; D008074:Lipoproteins / Q000737:chemistry / Q000378:metabolism*; D009154:Mutation; D011510:Proteolipids / Q000378:metabolism; D012996:Solutions
chemical_list: D018528:ATP-Binding Cassette Transporters; D003902:Detergents; D029968:Escherichia coli Proteins; D008024:Ligands; D008074:Lipoproteins; C407982:LolC protein, E coli; C407983:LolD protein, E coli; C407984:LolE protein, E coli; D011510:Proteolipids; D012996:Solutions; C020485:proteoliposomes; D000255:Adenosine Triphosphate