Selective distribution of a high-affinity plasminogen-binding site among group A streptococci associated with impetigo

Group A streptococci can be classified according to their tendency to cause either impetigo, pharyngitis, or both types of infection. Genotypic marker s for tissue site preference lie within emm genes, which encode fibrillar s urface proteins that play a key role in virulence. emm gene products (M and M-like proteins) display an extensive array of binding activities for tiss ue and plasma proteins of the human host. In a previous study, a high-affin ity binding site for human plasmin(ogen) was mapped to the emm53 gene produ ct. In this report, a structurally similar plasminogen-binding domain is fo und to be widely and selectively distributed among group A streptococci har boring the emm gene marker for the skin as the preferred tissue site for in fection. The findings are highly suggestive of a central role for bacterial modulation of host plasmin(ogen) during localized infection at the epiderm is.