Streptococcal surface proteins activate the contact system and control its antibacterial activity.
Group G streptococci (GGS) are important bacterial pathogens in humans. Here we investigate the interactions between GGS and the contact system, a pro-coagulant and pro-inflammatory proteolytic cascade, which upon activation also generates antibacterial peptides. Two surface proteins of GGS, protein FOG and protein G (PG), were found to bind contact system proteins. Experiments utilizing contact p