SCM, the M Protein of Streptococcus canis Binds Immunoglobulin G
Bergmann, Simone ;  Eichhom, Inga ;  Kohler, Thomas P. ;  Hammerschmidt, Sven ;  Goldmann, Oliver ;  Rohde, Manfred ;  Fulde, Marcus

HaupttitelSCM, the M Protein of Streptococcus canis Binds Immunoglobulin G
AutorBergmann, Simone
AutorEichhom, Inga
AutorKohler, Thomas P.
AutorHammerschmidt, Sven
AutorGoldmann, Oliver
AutorRohde, Manfred
AutorFulde, Marcus
Seitenzahl14 S.
Freie Schlagwörterzoonosis; Streptococcus canis; M protein; Immunoglobulin G; anti-phagocytic activity
DDC570 Biowissenschaften; Biologie
Auch erschienen inFront. Cell. Infect. Microbiol. - 7 (2017), Artikel Nr. 80
ZusammenfassungThe M protein of Streptococcus canis (SCM) is a virulence factor and serves as a surface-associated receptor with a particular affinity for mini-plasminogen, a cleavage product of the broad-spectrum serine protease plasmin. Here, we report that SCM has an additional high-affinity immunoglobulin G (IgG) binding activity. The ability of a particular S. canis isolate to bind to IgG significantly correlates with a scm-positive phenotype, suggesting a dominant role of SCM as an IgG receptor. Subsequent heterologous expression of SCM in non-IgG binding S. gordonii and Western Blot analysis with purified recombinant SCM proteins confirmed its IgG receptor function. As expected for a zoonotic agent, the SCM-IgG interaction is species-unspecific, with a particular affinity of SCM for IgGs derived from human, cats, dogs, horses, mice, and rabbits, but not from cows and goats. Similar to other streptococcal IgG-binding proteins, the interaction between SCM and IgG occurs via the conserved Fc domain and is, therefore, non-opsonic. Interestingly, the interaction between SCM and IgG-Fc on the bacterial surface specifically prevents opsonization by C1q, which might constitute another anti-phagocytic mechanism of SCM. Extensive binding analyses with a variety of different truncated SCM fragments defined a region of 52 amino acids located in the central part of the mature SCM protein which is important for IgG binding. This binding region is highly conserved among SCM proteins derived from different S. canis isolates but differs significantly from IgG-Fc receptors of S. pyogenes and S. dysgalactiae sub. equisimilis, respectively. In summary, we present an additional role of SCM in the pathogen-host interaction of S. canis. The detailed analysis of the SCM-IgG interaction should contribute to a better understanding of the complex roles of M proteins in streptococcal pathogenesis.
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Fachbereich/EinrichtungFB Biologie, Chemie, Pharmazie
Dokumententyp/-SammlungenWissenschaftlicher Artikel
RechteCreative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Anmerkungen des AutorsGefördert durch die DFG und den Open-Access-Publikationsfonds der Freien Universität
Erstellt am02.05.2017 - 12:05:04
Letzte Änderung09.05.2017 - 11:51:09
Statische URLhttp://edocs.fu-berlin.de/docs/receive/FUDOCS_document_000000026935