title: Structural and functional analysis of the tandem β-zipper interaction of a Streptococcal protein with human fibronectin.
abstract: Bacterial fibronectin-binding proteins (FnBPs) contain a large intrinsically disordered region (IDR) that mediates adhesion of bacteria to host tissues, and invasion of host cells, through binding to fibronectin (Fn). These FnBP IDRs consist of Fn-binding repeats (FnBRs) that form a highly extended tandem β-zipper interaction on binding to the N-terminal domain of Fn. Several FnBR residues are highly conserved across bacterial species, and here we investigate their contribution to the interaction. Mutation of these residues to alanine in SfbI-5 (a disordered FnBR from the human pathogen Streptococcus pyogenes) reduced binding, but for each residue the change in free energy of binding was <2 kcal/mol. The structure of an SfbI-5 peptide in complex with the second and third F1 modules from Fn confirms that the conserved FnBR residues play equivalent functional roles across bacterial species. Thus, in SfbI-5, the binding energy for the tandem β-zipper interaction with Fn is distributed across the interface rather than concentrated in a small number of "hot spot" residues that are frequently observed in the interactions of folded proteins. We propose that this might be a common feature of the interactions of IDRs and is likely to pose a challenge for the development of small molecule inhibitors of FnBP-mediated adhesion to and invasion of host cells.
authors.affiliation: Department of Biology, University of York, York, YO10 5DD, United Kingdom.
authors.forename: Nicole C
authors.initials: NC
authors.lastname: Norris
authors.affiliation: Department of Biology, University of York, York, YO10 5DD, United Kingdom.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Bingham
authors.affiliation: Department of Biology, University of York, York, YO10 5DD, United Kingdom.
authors.forename: Gemma
authors.initials: G
authors.lastname: Harris
authors.affiliation: Department of Biology, University of York, York, YO10 5DD, United Kingdom.
authors.forename: Adrian
authors.initials: A
authors.lastname: Speakman
authors.affiliation: Department of Biology, University of York, York, YO10 5DD, United Kingdom.
authors.forename: Richard P O
authors.initials: RPO
authors.lastname: Jones
authors.affiliation: Technology Facility, Department of Biology (Area 15), University of York, York, YO10 5DD, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Leech
authors.affiliation: Department of Chemistry, University of York, York, YO10 5DD, United Kingdom.
authors.forename: Johan P
authors.initials: JP
authors.lastname: Turkenburg
authors.affiliation: Department of Biology, University of York, York, YO10 5DD, United Kingdom; Department of Chemistry, University of York, York, YO10 5DD, United Kingdom. Electronic address: jennifer.potts@york.ac.uk.
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Potts
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry* / Q000378:metabolism; D002151:Calorimetry; D018360:Crystallography, X-Ray / Q000379:methods; D005353:Fibronectins / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008390:Markov Chains; D008968:Molecular Conformation; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D013297:Streptococcus pyogenes / Q000378:metabolism*; D020349:Surface Plasmon Resonance; D013816:Thermodynamics
chemical_list: D018829:Adhesins, Bacterial; D005353:Fibronectins; C078635:fibronectin-binding proteins, bacterial