Localization of the equine IgG-binding domain in the fibrinogen-binding protein (FgBP) of streptococcus equi subsp equi

Mary Meehan, Melanie J. Lewis, Caroline Byrne, David O'Hare, Jennifer M. Woof, Peter Owen

    Research output: Contribution to journalArticle

    8 Citations (Scopus)

    Abstract

    Fibrinogen-binding protein (FgBP, also termed SeM) is a cell-wall-associated anti-phagocytic M-like protein of the equine pathogen Streptococcus equi subsp. equi, and binds fibrinogen (Fg) and IgG. FgBP binds Fg avidly through residues located at the extreme N terminus of the molecule, whereas the IgG-binding site is more centrally located between the A and B repeats. FgBP binds equine IgG4 and IgG7 subclasses through interaction with the CH2-CH3 interdomain region of IgG-Fc, and possesses overlapping Fc-binding sites with protein A and protein G. In this study, FgBP truncates containing defined internal deletions were used to identify a stretch of 14 as (residues 335-348) critical for IgG binding. Protein chimeras consisting of the non-IgG-binding a-helical coiled-coil M5 protein fused to FgBP sequences were used to identify a minimal equine IgG-binding domain consisting of residues 329-360. Competition ELISA tests suggested that IgG does not compromise Fg binding and vice versa.

    Original languageEnglish
    Pages (from-to)2583-2592
    Number of pages10
    JournalMicrobiology
    Volume155
    DOIs
    Publication statusPublished - Aug 2009

    Keywords

    • GROUP-A STREPTOCOCCI
    • SURFACE-PROTEINS
    • IMMUNOGLOBULIN-G
    • SEQUENCE
    • REGION
    • GENE
    • CONTRIBUTES
    • COMPLEX
    • HORSES
    • SEM

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