title: The streptococcal binding site in the gelatin-binding domain of fibronectin is consistent with a non-linear arrangement of modules.
abstract: Fibronectin-binding proteins (FnBPs) of Staphylococcus aureus and Streptococcus pyogenes mediate invasion of human endothelial and epithelial cells in a process likely to aid the persistence and/or dissemination of infection. In addition to binding sites for the N-terminal domain (NTD) of fibronectin (Fn), a number of streptococcal FnBPs also contain an upstream region (UR) that is closely associated with an NTD-binding region; UR binds to the adjacent gelatin-binding domain (GBD) of Fn. Previously, UR was shown to be required for efficient streptococcal invasion of epithelial cells. Here we show, using a Streptococcus zooepidemicus FnBP, that the UR-binding site in GBD resides largely in the (8)F1(9)F1 module pair. We also show that UR inhibits binding of a peptide from the α1 chain of type I collagen to (8)F1(9)F1 and that UR binding to (8)F1 is likely to occur through anti-parallel β-zipper formation. Thus, we propose that streptococcal proteins that contain adjacent NTD- and GBD-binding sites form a highly unusual extended tandem β-zipper that spans the two domains and mediates high affinity binding to Fn through a large intermolecular interface. The proximity of the UR- and NTD-binding sequences in streptococcal FnBPs is consistent with a non-linear arrangement of modules in the tertiary structure of the GBD of Fn.
authors.affiliation: Department of Biology, University of York, Heslington, York, YO10 5DD, United Kingdom.
authors.forename: Kate E
authors.initials: KE
authors.lastname: Atkin
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Brentnall
authors.forename: Gemma
authors.initials: G
authors.lastname: Harris
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Bingham
authors.forename: Michele C
authors.initials: MC
authors.lastname: Erat
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Millard
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schwarz-Linek
authors.forename: David
authors.initials: D
authors.lastname: Staunton
authors.forename: Ioannis
authors.initials: I
authors.lastname: Vakonakis
authors.forename: Iain D
authors.initials: ID
authors.lastname: Campbell
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Potts
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D005353:Fibronectins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005780:Gelatin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D018502:Streptococcus equi / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005353:Fibronectins; D011994:Recombinant Proteins; D005780:Gelatin