Background: Streptococcus canis (S. canis) is a Lancefield group-G opportunistic pathogen that infects predominantly animals, but also causes infections in humans. S. canis colonises the mucosal surfaces and skin of the host. This project is focused on the functional role of the S. canis protein IdeC. Specifically, what role this protein may play in mediating host-pathogen interactions.
IdeC is an IgG specific protease, suggested to act with a similar mechanism to IdeS of Streptococcus pyogenes, a secreted cysteine kinase that cleaves the hinge region of IgG. IdeC has an Arg-Gly-Asp (RGD) motif, this is the minimal peptide sequence required to bind integrins. Bacterial proteins containing RGD motifs have been implicated in adhesion and invasion of host cells. This along with the ability of IdeC to bind back to the bacterial surface after secretion suggest a possible second function of IdeC in adhesion.
Methods: Fluorescent latex beads coated in recombinant IdeC protein are used to assess the interaction of IdeC with epithelial and endothelial cells. Further, a recombinant protein with RGD replaced with RGE has been produced to test the role of the motif in any interaction observed.
Results: Based on fluorescence microscopy analysis, IdeC coated latex beads displayed increased interaction with both epithelial and endothelial cells when compared to IdeC_RGE and BSA controls. Electron microscopy indicates that IdeC coated beads may be internalised however, a mechanism is yet to be determined.
Conclusions: Streptococcal protein IdeC may have a second function, involving bacterial attachment and invasion into host cells during infection.