title: Novel mutations of the LolCDE complex causing outer membrane localization of lipoproteins despite their inner membrane-retention signals.
abstract: In Gram-negative bacteria, lipoproteins are targeted to either the inner or outer membrane depending on their sorting signals. An ABC transporter LolCDE complex in Escherichia coli releases outer membrane-specific lipoproteins. Inner membrane-specific lipoproteins remain in the inner membrane because they each have a LolCDE-avoidance signal and therefore are not released by LolCDE. Only the LolC(A40P) mutation was previously found to cause outer membrane localization of lipoproteins despite their inner membrane-retention signals. Here, we isolated several new LolCDE mutants that cause outer membrane localization of lipoproteins possessing LolCDE-avoidance signals. Mutations were found in all three subunits of LolCDE, including the cytoplasmic ATPase subunit LolD. However, the extent of outer membrane sorting of inner membrane-specific lipoproteins differed depending on the mutation. Based on these observations, the molecular events underlying the recognition of lipoproteins by the LolCDE complex are discussed.
authors.affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Sakamoto
authors.forename: Rika
authors.initials: R
authors.lastname: Satou
authors.forename: Hajime
authors.initials: H
authors.lastname: Tokuda
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Narita
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000445:Aldehyde Oxidoreductases / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006427:Hemin / Q000737:chemistry / Q000378:metabolism; D008074:Lipoproteins / Q000378:metabolism*; D009154:Mutation
chemical_list: D018528:ATP-Binding Cassette Transporters; D003470:Culture Media; D029968:Escherichia coli Proteins; D008074:Lipoproteins; C407982:LolC protein, E coli; C407983:LolD protein, E coli; C407984:LolE protein, E coli; D006427:Hemin; D000445:Aldehyde Oxidoreductases; C067282:glutamyl tRNA reductase