title: Crystal structures of bacterial lipoprotein localization factors, LolA and LolB.
abstract: Lipoproteins having a lipid-modified cysteine at the N-terminus are localized on either the inner or the outer membrane of Escherichia coli depending on the residue at position 2. Five Lol proteins involved in the sorting and membrane localization of lipoprotein are highly conserved in Gram-negative bacteria. We determined the crystal structures of a periplasmic chaperone, LolA, and an outer membrane lipoprotein receptor, LolB. Despite their dissimilar amino acid sequences, the structures of LolA and LolB are strikingly similar to each other. Both have a hydrophobic cavity consisting of an unclosed beta barrel and an alpha-helical lid. The cavity represents a possible binding site for the lipid moiety of lipoproteins. Detailed structural differences between the two proteins provide significant insights into the molecular mechanisms underlying the energy-independent transfer of lipoproteins from LolA to LolB and from LolB to the outer membrane. Furthermore, the structures of both LolA and LolB determined from different crystal forms revealed the distinct structural dynamics regarding the association and dissociation of lipoproteins. The results are discussed in the context of the current model for the lipoprotein transfer from the inner to the outer membrane through a hydrophilic environment.
authors.affiliation: RIKEN Harima Institute/SPring-8, Koto 1-1-1, Mikazuki-cho, Sayo-gun, Hyogo 679-5148, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Takeda
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Miyatake
authors.forename: Naoko
authors.initials: N
authors.lastname: Yokota
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Matsuyama
authors.forename: Hajime
authors.initials: H
authors.lastname: Tokuda
authors.forename: Kunio
authors.initials: K
authors.lastname: Miki
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry*; D002352:Carrier Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D008958:Models, Molecular; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D033902:Periplasmic Binding Proteins / Q000737:chemistry*; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C116111:LolA protein, E coli; C087012:LolB protein, E coli; D018832:Molecular Chaperones; D033902:Periplasmic Binding Proteins