title: Dissection of pilus tip assembly by the FimD usher monomer.
abstract: Type 1 pili are representative of a class of bacterial surface structures assembled by the conserved chaperone/usher pathway and used by uropathogenic Escherichia coli to attach to bladder cells during infection. The outer membrane assembly platform-the usher-is critical for the formation of pili, catalysing the polymerisation of pilus subunits and enabling the secretion of the nascent pilus. Despite extensive structural characterisation of the usher, a number of questions about its mechanism remain, notably its oligomerisation state, and how it orchestrates the ordered assembly of pilus subunits. We demonstrate here that the FimD usher is able to catalyse in vitro pilus assembly effectively in its monomeric form. Furthermore, by establishing the kinetics of usher-catalysed reactions between various pilus subunits, we establish a complete kinetic model of tip fibrillum assembly, able to account for the order of subunits in native type 1 pili.
authors.affiliation: Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK.
authors.forename: William J
authors.initials: WJ
authors.lastname: Allen
authors.forename: Gilles
authors.initials: G
authors.lastname: Phan
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Hultgren
authors.forename: Gabriel
authors.initials: G
authors.lastname: Waksman
mesh_terms: D018830:Adhesins, Escherichia coli / Q000737:chemistry / Q000378:metabolism; 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*; D007700:Kinetics; D008958:Models, Molecular; D011485:Protein Binding; D055503:Protein Multimerization; D014461:Ultracentrifugation
chemical_list: D018830:Adhesins, Escherichia coli; D029968:Escherichia coli Proteins; C521674:FimF protein, E coli; C489721:fimC protein, E coli; C058769:fimH protein, E coli; D036781:Fimbriae Proteins