title: Structural insight into host recognition by aggregative adherence fimbriae of enteroaggregative Escherichia coli.
abstract: Enteroaggregative Escherichia coli (EAEC) is a leading cause of acute and persistent diarrhea worldwide. A recently emerged Shiga-toxin-producing strain of EAEC resulted in significant mortality and morbidity due to progressive development of hemolytic-uremic syndrome. The attachment of EAEC to the human intestinal mucosa is mediated by aggregative adherence fimbria (AAF). Using X-ray crystallography and NMR structures, we present new atomic resolution insight into the structure of AAF variant I from the strain that caused the deadly outbreak in Germany in 2011, and AAF variant II from archetype strain 042, and propose a mechanism for AAF-mediated adhesion and biofilm formation. Our work shows that major subunits of AAF assemble into linear polymers by donor strand complementation where a single minor subunit is inserted at the tip of the polymer by accepting the donor strand from the terminal major subunit. Whereas the minor subunits of AAF have a distinct conserved structure, AAF major subunits display large structural differences, affecting the overall pilus architecture. These structures suggest a mechanism for AAF-mediated adhesion and biofilm formation. Binding experiments using wild type and mutant subunits (NMR and SPR) and bacteria (ELISA) revealed that despite the structural differences AAF recognize a common receptor, fibronectin, by employing clusters of basic residues at the junction between subunits in the pilus. We show that AAF-fibronectin attachment is based primarily on electrostatic interactions, a mechanism not reported previously for bacterial adhesion to biotic surfaces.
authors.affiliation: Center for Vaccine Development, Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Andrea A
authors.initials: AA
authors.lastname: Berry
authors.affiliation: Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Chemistry, University of Turku, Turku, JBL, Arcanum, Turku, Finland.
authors.forename: Natalia
authors.initials: N
authors.lastname: Pakharukova
authors.affiliation: Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom.
authors.forename: James A
authors.initials: JA
authors.lastname: Garnett
authors.affiliation: Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom.
authors.forename: Wei-chao
authors.initials: WC
authors.lastname: Lee
authors.affiliation: Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Cota
authors.affiliation: Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Marchant
authors.affiliation: Department of Chemistry, University of Turku, Turku, JBL, Arcanum, Turku, Finland; Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCentre, Uppsala, Sweden.
authors.forename: Saumendra
authors.initials: S
authors.lastname: Roy
authors.affiliation: Department of Chemistry, University of Turku, Turku, JBL, Arcanum, Turku, Finland.
authors.forename: Minna
authors.initials: M
authors.lastname: Tuittila
authors.affiliation: Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom.
authors.forename: Bing
authors.initials: B
authors.lastname: Liu
authors.affiliation: Paragon Bioservices, Inc, Baltimore, Maryland, United States of America.
authors.forename: Keith G
authors.initials: KG
authors.lastname: Inman
authors.affiliation: Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America.
authors.forename: Fernando
authors.initials: F
authors.lastname: Ruiz-Perez
authors.affiliation: Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America.
authors.forename: Inacio
authors.initials: I
authors.lastname: Mandomando
authors.affiliation: Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America.
authors.forename: James P
authors.initials: JP
authors.lastname: Nataro
authors.affiliation: Department of Chemistry, University of Turku, Turku, JBL, Arcanum, Turku, Finland.
authors.forename: Anton V
authors.initials: AV
authors.lastname: Zavialov
authors.affiliation: Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom.
authors.forename: Steve
authors.initials: S
authors.lastname: Matthews
mesh_terms: D018830:Adhesins, Escherichia coli / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion / Q000276:immunology*; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000276:immunology* / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000737:chemistry*; D054884:Host-Pathogen Interactions / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D007413:Intestinal Mucosa / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D009682:Magnetic Resonance Spectroscopy; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D018830:Adhesins, Escherichia coli; D029968:Escherichia coli Proteins; D005353:Fibronectins