Hyaluronate lyase and sialidase in the anginosus streptococci: As the putative virulence factors

Among the anginosus streptococci, two types of hyaluronate lyase (HAase) gene were distributed species-specifically and the coded enzymes were different from each other in their molecular size and substrate range. Streptococcus intermedius and Streptococcus constellatus subsp. pharyngis produced the same HAase that degraded both hyaluronan and chondroitin sulfate A, while another type of HAase produced by Streptococcus constellatus subsp. constellatus depolymerized only hyaluronan. The deduced amino acid sequence of the former showed the highest similarity to HAase of Streptococcus pneumoniae, a pathogenic member within the mitis group. In addition, sialidase of S. intermedius was also most similar to the major sialidase of S. pneumoniae, NanA. Therefore, interspecies-transfer of these glycosidase genes may have occurred among the streptococcal groups. As the putative virulence factors which can degrade or modify the host tissue sugar chains, both the HAases and the NanA-like sialidase should be studied more closely.