Structural highlights
FunctionPublication Abstract from PubMedThe arsenal of virulence factors deployed by streptococci include streptococcal collagen-like (Scl) proteins. These proteins, which are characterized by a globular and a collagen-like domain, play key roles in host-adhesion, host immune defense evasion and biofilm formation. In this work, we demonstrate that the Scl2.3 protein is expressed on the surface of invasive M3-type strain MGAS315 of Streptococcus pyogenes. We report the crystal structure of Scl2.3 globular domain, the first of any Scl. This structure shows a novel fold among collagen trimerization domains, of either bacterial or human origin. Despite there being low sequence identity, we observe that Scl2.3 globular domain structurally resembles the gp41 subunit of the envelope glycoprotein from human immunodeficiency virus type 1, an essential subunit for viral fusion to human T cells. We combined crystallographic data with modeling and molecular dynamics techniques to gather information on the entire lollipop-like Scl2.3 structure. Molecular dynamics data evidence a high flexibility of Scl2.3, with remarkable inter-domain motions which are likely instrumental to the protein biological function in mediating adhesive or immune-modulatory functions in host-pathogen interactions. Altogether, our results provide molecular tools for the understanding of Scl-mediated streptococcal pathogenesis and important structural insights for the future design of small molecular inhibitors of streptococcal invasion. 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.,Squeglia F, Bachert B, De Simone A, Lukomski S, Berisio R J Biol Chem. 2013 Dec 19. PMID:24356966[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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