Purification and characterization of Streptococcus pyogenes erythrogenic toxin type A produced by a cloned gene in Streptococcus sanguis.

The gene of Streptococcus pyogenes erythrogenic toxin type A (speA) has been previously cloned in Streptococcus sanguis (Challis) and produces extracellular erythrogenic toxin type A (ET A). The ET A produced and secreted by this heterologous host was purified to homogeneity and shown to have properties identical to ET A produced by S. pyogenes strain NY-5; i.e., serological identity in immunodiffusion, migration in SDS-polyacrylamide gel electrophoresis, mitogenic activity, inhibition of mitogenic activity by specific antibody, and precipitation by an international scarlatina antitoxin preparation. The cloned speA gene specified an ET A which had a molecular weight identical to that of ET A from S. pyogenes previously reported from this laboratory. NH2-terminal sequence determination of the purified protein showed the first nine residues to be gln gln asp pro asp pro ser gln leu; this is consistent with predictions made from the nucleotide sequence of the speA gene according to Weeks and Ferretti and different from the sequence published by Johnson et al.