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

TY - JOUR

T1 - Localization of the equine IgG-binding domain in the fibrinogen-binding protein (FgBP) of streptococcus equi subsp equi

AU - Meehan, Mary

AU - Lewis, Melanie J.

AU - Byrne, Caroline

AU - O'Hare, David

AU - Woof, Jennifer M.

AU - Owen, Peter

PY - 2009/8

Y1 - 2009/8

N2 - 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.

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 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.

KW - GROUP-A STREPTOCOCCI

KW - SURFACE-PROTEINS

KW - IMMUNOGLOBULIN-G

KW - SEQUENCE

KW - REGION

KW - GENE

KW - CONTRIBUTES

KW - COMPLEX

KW - HORSES

KW - SEM

U2 - 10.1099/mic.0.028845-0

DO - 10.1099/mic.0.028845-0

M3 - Article

C2 - 19423628

SN - 1350-0872

VL - 155

SP - 2583

EP - 2592

JO - Microbiology

JF - Microbiology

ER -