RT Journal Article SR Electronic(1) A1 Meehan, Mary A1 Lewis, Melanie J. A1 Byrne, Caroline A1 O'Hare, David A1 Woof, Jenny M. A1 Owen, PeterYR 2009 T1 Localization of the equine IgG-binding domain in the fibrinogen-binding protein (FgBP) of Streptococcus equi subsp. equi JF Microbiology, VO 155 IS 8 SP 2583 OP 2592 DO https://doi.org/10.1099/mic.0.028845-0 PB Microbiology Society, SN 1465-2080, AB 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., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.028845-0