%0 Journal Article %A Meehan, Mary %A Lewis, Melanie J. %A Byrne, Caroline %A O'Hare, David %A Woof, Jenny M. %A Owen, Peter %T Localization of the equine IgG-binding domain in the fibrinogen-binding protein (FgBP) of Streptococcus equi subsp. equi %D 2009 %J Microbiology, %V 155 %N 8 %P 2583-2592 %@ 1465-2080 %R https://doi.org/10.1099/mic.0.028845-0 %K eqFg, equine Fg %K Fg, fibrinogen %K HRP, horseradish peroxidase %K eqIgG, equine IgG %K FgBP, fibrinogen-binding protein %I Microbiology Society, %X 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 aa (residues 335–348) critical for IgG binding. Protein chimeras consisting of the non-IgG-binding α-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. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.028845-0