The Crystal Structure of the Streptococcal Collagen- like Protein 2 Globular Domain from Invasive M3-type Group A Streptococcus Shows Significant Similarity to Immunomodulatory HIV Protein gp41*

Background: Streptococcal collagen-like proteins play crucial roles in host adhesion, host cell entry, and immunomodulation of host defenses. Results: This study provides the first three-dimensional structural description of a streptococcal collagen-like protein. Conclusion: The crystal structure evidences a six-helical bundle fold, which is unusual in bacterial proteins and characteristic of viral fusion proteins. Significance: The high resolution structure provides a structural basis for the design of inhibitors of streptococcal invasion.