title: Valency conversion in the type 1 fimbrial adhesin of Escherichia coli.
abstract: FimH protein is a lectin-like adhesive subunit of type 1, or mannose-sensitive, fimbriae that are found on the surface of most Escherichia coli strains. All naturally occurring FimH variants demonstrate a conserved mannotriose-specific (i.e. multivalent) binding. Here, we demonstrate that replacement of residues 185-279 within the FimH pilin domain with a corresponding segment of the type 1C fimbrial adhesin FocH leads to a loss of the multivalent mannotriose-specific binding property accompanied by the acquisition of a distinct monomannose-specific (i.e. monovalent) binding capability. Bacteria expressing the monovalent hybrid adhesins were capable of binding strongly to uroepithelial tissue culture cells and guinea pig erythrocytes. They could not, however, agglutinate yeast or bind human buccal cells -- functions readily accomplished by the E. coli-expressing mannotriose-specific FimH variants. Based on the relative potency of inhibiting compounds of different structures, the receptor binding site within monovalent FimH-FocH adhesin has an extended structure with an overall configuration similar to that within the multivalent FimH of natural origin. The monomannose-only specific phenotype could also be invoked by a single point mutation, E89K, located within the lectin domain of FimH, but distant from the receptor binding site. The structural alterations influence the receptor-binding valency of the FimH adhesin via distal effects on the combining pocket, obviously by affecting the FimH quaternary structure.
authors.affiliation: Department of Microbiology, University of Washington, Seattle, WA 98195-7242, USA. evs@u.washington.edu
authors.forename: E V
authors.initials: EV
authors.lastname: Sokurenko
authors.forename: M A
authors.initials: MA
authors.lastname: Schembri
authors.forename: E
authors.initials: E
authors.lastname: Trintchina
authors.forename: K
authors.initials: K
authors.lastname: Kjaergaard
authors.forename: D L
authors.initials: DL
authors.lastname: Hasty
authors.forename: P
authors.initials: P
authors.lastname: Klemm
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018830:Adhesins, Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000371:Agglutination / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D006224:Cricetinae; D004912:Erythrocytes / Q000378:metabolism / Q000382:microbiology; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D036781:Fimbriae Proteins; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D008766:Methylmannosides / Q000494:pharmacology; D008969:Molecular Sequence Data; D010641:Phenotype; D017354:Point Mutation / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012709:Serum Albumin / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D018830:Adhesins, Escherichia coli; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D008766:Methylmannosides; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D012709:Serum Albumin; C058769:fimH protein, E coli; D036781:Fimbriae Proteins; D012260:Ribonucleases; C029600:ribonuclease B