title: Identification and characterization of the chaperone-subunit complex-binding domain from the type 1 pilus assembly platform FimD.
abstract: The outer membrane protein FimD represents the assembly platform of adhesive type 1 pili from Escherichia coli. FimD forms ring-shaped oligomers of 91.4 kDa subunits that recognize complexes between the pilus chaperone FimC and individual pilus subunits in the periplasm and mediate subunit translocation through the outer membrane. Here, we have identified a periplasmic domain of FimD (FimD(N)) comprising the N-terminal 139 residues of FimD. Purified FimD(N) is a monomeric, soluble protein that specifically recognizes complexes between FimC and individual type 1 pilus subunits, but does not bind the isolated chaperone, or isolated subunits. In addition, FimD(N) retains the ability of FimD to recognize different chaperone-subunit complexes with different affinities, and has the highest affinity towards the FimC-FimH complex. Overexpression of FimD(N) in the periplasm of wild-type E.coli cells diminished incorporation of FimH at the tip of type 1 pili, while pilus assembly itself was not affected. The identification of FimD(N) and its ternary complexes with FimC and individual pilus subunits opens the avenue to structural characterization of critical type 1 pilus assembly intermediates.
authors.affiliation: Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule Hönggerberg, CH-8093 Zürich, Switzerland.
authors.forename: Mireille
authors.initials: M
authors.lastname: Nishiyama
authors.forename: Michael
authors.initials: M
authors.lastname: Vetsch
authors.forename: Chasper
authors.initials: C
authors.lastname: Puorger
authors.forename: Ilian
authors.initials: I
authors.lastname: Jelesarov
authors.forename: Rudi
authors.initials: R
authors.lastname: Glockshuber
mesh_terms: D018830:Adhesins, Escherichia coli / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001665:Binding Sites; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D036781:Fimbriae Proteins / Q000737:chemistry* / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D046911:Macromolecular Substances; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D019897:Periplasm / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000502:physiology; D017386:Sequence Homology, Amino Acid
chemical_list: D018830:Adhesins, Escherichia coli; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C098025:FaeD protein, E coli; D046911:Macromolecular Substances; D018832:Molecular Chaperones; C489721:fimC protein, E coli; C489283:fimD protein, E coli; C063629:fimD protein, bacteria; C058769:fimH protein, E coli; D036781:Fimbriae Proteins