title: NMR studies of interactions between periplasmic chaperones from uropathogenic E. coli and pilicides that interfere with chaperone function and pilus assembly.
abstract: Adherence of uropathogenic Escherichia coli to host tissue is mediated by pili, which are hair-like protein structures extending from the outer cell membrane of the bacterium. The chaperones FimC and PapD are key components in pilus assembly since they catalyse folding of subunits that are incorporated in type 1 and P pili, respectively, and also transport the subunits across the periplasmic space. Recently, compounds that inhibit pilus biogenesis and interfere with chaperone-subunit interactions have been discovered and termed pilicides. In this paper NMR spectroscopy was used to study the interaction of different pilicides with PapD and FimC in order to gain structural knowledge that would explain the effect that some pilicides have on pilus assembly. First relaxation-edited NMR experiments revealed that the pilicides bound to the PapD chaperone with mM affinity. Then the pilicide-chaperone interaction surface was investigated through chemical shift mapping using 15N-labelled FimC. Principal component analysis performed on the chemical shift perturbation data revealed the presence of three binding sites on the surface of FimC, which interacted with three different classes of pilicides. Analysis of structure-activity relationships suggested that pilicides reduce pilus assembly in E. coli either by binding in the cleft of the chaperone, or by influencing the orientation of the flexible F1-G1 loop, both of which are part of the surface by which the chaperone forms complexes with pilus subunits. It is suggested that binding to either of these sites interferes with folding of the pilus subunits, which occurs during formation of the chaperone-subunit complexes. In addition, pilicides that influence the F1-G1 loop also appear to reduce pilus formation by their ability to dissociate chaperone-subunit complexes.
authors.affiliation: Organic Chemistry, Department of Chemistry, Umeå University, SE-901 87, Umeå, Sweden.
authors.forename: Mattias
authors.initials: M
authors.lastname: Hedenström
authors.forename: Hans
authors.initials: H
authors.lastname: Emtenäs
authors.forename: Nils
authors.initials: N
authors.lastname: Pemberton
authors.forename: Veronica
authors.initials: V
authors.lastname: Aberg
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Hultgren
authors.forename: Jerome S
authors.initials: JS
authors.lastname: Pinkner
authors.forename: Viola
authors.initials: V
authors.lastname: Tegman
authors.forename: Fredrik
authors.initials: F
authors.lastname: Almqvist
authors.forename: Ingmar
authors.initials: I
authors.lastname: Sethson
authors.forename: Jan
authors.initials: J
authors.lastname: Kihlberg
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D001665:Binding Sites; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D036781:Fimbriae Proteins / Q000737:chemistry / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000187:drug effects* / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D033903:Periplasmic Proteins / Q000737:chemistry / Q000378:metabolism; D011728:Pyridones / Q000494:pharmacology; D014443:Tyrosine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; C084330:PapD protein, E coli; D033903:Periplasmic Proteins; D011728:Pyridones; C489721:fimC protein, E coli; D036781:Fimbriae Proteins; D014443:Tyrosine