title: Structure-function analysis of BfpB, a secretin-like protein encoded by the bundle-forming-pilus operon of enteropathogenic Escherichia coli.
abstract: Production of type IV bundle-forming pili by enteropathogenic Escherichia coli (EPEC) requires BfpB, an outer-membrane lipoprotein and member of the secretin protein superfamily. BfpB was found to compose a ring-shaped, high-molecular-weight outer-membrane complex that is stable in 4% sodium dodecyl sulfate at temperatures of < or = 65 degrees C. Chemical cross-linking and immunoprecipitation experiments disclosed that the BfpB multimeric complex interacts with BfpG, and mutational studies showed that BfpG is required for the formation and/or stability of the multimer but not for the outer-membrane localization of BfpB. Formation of the BfpB multimer also does not require BfpA, the repeating subunit of the pilus filament. Functional studies of the BfpB-BfpG complex revealed that its presence confers vancomycin sensitivity, indicating that it may form an incompletely gated channel through the outer membrane. BfpB expression is also associated with accumulation of EPEC proteins in growth medium, suggesting that it may support both pilus biogenesis and protein secretion.
authors.affiliation: Departments of Medicine (Infectious Diseases and Geographic Medicine) and Microbiology & Immunology, Stanford Medical School, Stanford, California 94305, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Schmidt
authors.forename: D
authors.initials: D
authors.lastname: Bieber
authors.forename: S W
authors.initials: SW
authors.lastname: Ramer
authors.forename: J
authors.initials: J
authors.lastname: Hwang
authors.forename: C Y
authors.initials: CY
authors.lastname: Wu
authors.forename: G
authors.initials: G
authors.lastname: Schoolnik
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D029968:Escherichia coli Proteins; D010861:Fimbriae, Bacterial / Q000235:genetics*; D008074:Lipoproteins / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009876:Operon; D018272:Porins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D012633:Secretin / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D001425:Bacterial Outer Membrane Proteins; C433794:BfpB protein, E coli; D029968:Escherichia coli Proteins; D008074:Lipoproteins; D046911:Macromolecular Substances; D018272:Porins; D012633:Secretin; D014640:Vancomycin