Functional characterization of DRS from Streptococcus pyogenes M12 and M55 serotypes

The mature streptococcal secretary proteins, SIC and DRS, show similarity only in the proline-rich region (PRR). However, these proteins share some biological functions. In particular, both SIC and DRS inhibit anti-microbial beta-defensins. Interestingly, this activity does not seem confined to the common PRR but to other portions of the molecule that share little sequence homology.