FIG. 1.

Schematic representation of the mga5 and mga22 regulons and the mutants used in this study. (A) Organization of the mga regulons of the type 5 strain M5 Manfredo and the type 22 strain AL168. Replacement of the emm5 gene with a gene encoding kanamycin resistance (Ωkm2) by homologous recombination gave rise to strain ΔM5 (10). In the AL168(mrp emm) derivative, the mrp22 gene has been disrupted by insertion of the conjugative transposon Tn916, whereas a large part of the emm22 gene has been replaced by a kanamycin casette (32). The mga gene encodes the multigene activator of group A streptococcus, and the mrp, emm, and enn genes encode proteins in the M protein family, whereas the scpA gene encodes the streptococcal C5a peptidase. The regions in the proteins marked A, B, and C are distinct domains containing three to five different repeat units. (B) Organization of the mga regulon of the ΔM5/emm22 derivative of the M5 Manfredo strain, in which the emm5 gene has been replaced by the emm22 gene. Protein ligands that are relevant for this study and their binding sites in M5 (Fg [fibrinogen] and FHL-1) and Emm22 (IgA and C4BP) are indicated.