Open AccessStaphylococcal Complement Inhibitor Modulates Phagocyte Responses by Dimerization of Convertases
Author(s) -
Ilse Jongerius,
Ma Puister,
Jiawang Wu,
Maartje Ruyken,
Jos A. G. van Strijp,
Suzan H. M. Rooijakkers
Publication year - 2009
Publication title -
the journal of immunology/the journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.737
H-Index - 372
eISSN - 1550-6606
pISSN - 0022-1767
DOI - 10.4049/jimmunol.0902865
Subject(s) - complement receptor , alternative complement pathway , complement system , c3 convertase , immune system , complement receptor 1 , complement component 2 , phagocytosis , classical complement pathway , receptor , complement (music) , microbiology and biotechnology , biology , biochemistry , immunology , gene , phenotype , complementation
The human pathogen Staphylococcus aureus produces several complement-evasion molecules that enable the bacterium to withstand the host immune response. The human-specific staphylococcal complement inhibitor (SCIN) blocks the central C3 convertase enzymes that trigger critical complement functions, such as C3b deposition, phagocytosis, and C5a generation. SCIN effectively blocks the conversion of C3 by alternative pathway C3 convertases (C3bBb), but also induces dimerization of these enzymes. In this study, we show that formation of dimeric convertases by SCIN is important for S. aureus immune evasion because it modulates complement recognition by phagocytic receptors. Dimeric, but not monomeric, SCIN convertases showed an impaired binding to complement receptor 1 and the complement receptor of the Ig superfamily. The dimerization site of SCIN is essential for its strong antiphagocytic properties. These studies provide critical insights into the unique immune-evasion strategies used by S. aureus.