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Structural and functional studies of intrinsically disordered fibronectin-binding proteins

Norris, Nicole Catherine (2009) Structural and functional studies of intrinsically disordered fibronectin-binding proteins. PhD thesis, University of York.

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Abstract

Bacterial fibronectin-binding proteins (FnBPs) mediate adhesion of bacteria to host tissues through binding to the human protein fibronectin (Fn). FnBPs are predicted to contain a series of intrinsically disordered Fn-binding repeats (FnBRs), which undergo a disorder-to-order transition on binding up to five F1-modules (1−5F1) from the N terminal domain of Fn through a tandem β-zipper interaction. This work investigated these predictions for SfbI-5, an FnBR from the important human pathogen Streptococcus pyogenes. SfbI-5 was shown to behave as an intrinsically disordered protein (IDP), with no stable secondary or tertiary structure. The C terminal third of SfbI 5 was shown to have propensity for β-strand conformations and, thus, might contain a preformed contact site involved in the initial interaction between SfbI-5 and 1−5F1. A high resolution structure of an SfbI-5 peptide in complex with 2F13F1 demonstrated that peptide binding occurs through formation of a tandem β-zipper with the concomitant formation of a large, extended intermolecular interface. Conserved FnBR residues play roles similar to those played by residues in related complexes involving Staphylococcus aureus FnBRs. The effect of mutating these residues on SfbI-5 binding to 1−5F1 was shown to be modest, suggesting that large, extended interfaces, when formed by IDPs, might be tolerant to mutations in the IDP. A putative FnBR, TickFnBR, was identified in a salivary protein from the blood-feeding tick Ixodes scapularis, which is a vector for human diseases. TickFnBR was shown to bind to 1−5F1 and also to Fn in human plasma. A high resolution structure demonstrated that a TickFnBR peptide binds to 2F13F1 through a tandem β-zipper. TickFnBR is the first eukaryotic FnBR to be identified, suggesting the tandem β zipper interaction is a useful mechanism for harmful organisms to target and exploit human Fn.

Item Type: Thesis (PhD)
Keywords: fibronectin, fibronectin-binding protein, intrinsically disordered, natively unstructured, group A streptococcus, Streptococcus pyogenes, Staphylococcus aureus, FnBPA, FnBPB, prtF, Protein F1, prtF1, hidden Markov model, NMR chemical shift analysis, secondary structure propensity, alanine scanning mutagenesis, change in Gibbs free energy on binding
Academic Units: The University of York > Biology (York)
Depositing User: Miss Nicole Catherine Norris
Date Deposited: 20 Jan 2010 11:36
Last Modified: 08 Aug 2013 08:43
URI: http://etheses.whiterose.ac.uk/id/eprint/570

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