title: The type IV pilus assembly complex: biogenic interactions among the bundle-forming pilus proteins of enteropathogenic Escherichia coli.
abstract: Production of type IV bundle-forming pili (BFP) by enteropathogenic Escherichia coli (EPEC) requires the protein products of 12 genes of the 14-gene bfp operon. Antisera against each of these proteins were used to demonstrate that in-frame deletion of individual genes within the operon reduces the abundance of other bfp operon-encoded proteins. This result was demonstrated not to be due to downstream polar effects of the mutations but rather was taken as evidence for protein-protein interactions and their role in the stabilization of the BFP assembly complex. These data, combined with the results of cell compartment localization studies, suggest that pilus formation requires the presence of a topographically discrete assembly complex that is composed of BFP proteins in stoichiometric amounts. The assembly complex appears to consist of an inner membrane component containing three processed, pilin-like proteins, BfpI, -J, and -K, that localize with BfpE, -L, and -A (the major pilin subunit); an outer membrane, secretin-like component, BfpB and -G; and a periplasmic component composed of BfpU. Of these, only BfpL consistently localizes with both the inner and outer membranes and thus, together with BfpU, may articulate between the Bfp proteins in the inner membrane and outer membrane compartments.
authors.affiliation: Department of Medicine (Infectious Diseases and Geographic Medicine) and Microbiology & Immunology, Stanford Medical School, Stanford, California 94305, USA.
authors.forename: Sandra W
authors.initials: SW
authors.lastname: Ramer
authors.forename: Gary K
authors.initials: GK
authors.lastname: Schoolnik
authors.forename: Cheng-Yen
authors.initials: CY
authors.lastname: Wu
authors.forename: Jaiweon
authors.initials: J
authors.lastname: Hwang
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Schmidt
authors.forename: David
authors.initials: D
authors.lastname: Bieber
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D003429:Cross Reactions; D004926:Escherichia coli / Q000472:pathogenicity / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D008074:Lipoproteins; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames; D009876:Operon
chemical_list: D001425:Bacterial Outer Membrane Proteins; C104901:BfpA protein, E coli; C433794:BfpB protein, E coli; C000608621:BfpI protein, E coli; C000608622:BfpJ protein, E coli; D029968:Escherichia coli Proteins; D008074:Lipoproteins; D036781:Fimbriae Proteins