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Group A streptococcal phagocytosis resistance is independent of complement factor H and factor H‐like protein 1 binding
Author(s) -
Kotarsky Heike,
Gustafsson Maria,
Svensson Henrik G.,
Zipfel Peter F.,
Truedsson Lennart,
Sjöbring Ulf
Publication year - 2001
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2001.02496.x
Subject(s) - phagocytosis , factor h , alternative complement pathway , complement system , biology , microbiology and biotechnology , classical complement pathway , bacteria , complement factor b , complement factor i , plasma protein binding , streptococcus , c3 convertase , streptococcus pyogenes , antibody , biochemistry , staphylococcus aureus , immunology , genetics
Factor H (FH) and factor H‐like protein 1 (FHL‐1) regulate complement activation through the alternative pathway. Several extracellular bacterial pathogens, prime targets for the complement system, bind FH and FHL‐1, thereby acquiring a potential mechanism for minimizing complement deposition on their surface. For group A streptococci (GAS), surface‐bound antiphagocytic M proteins mediate the interaction. To study the role of the FH–FHL‐1 interaction for complement deposition and opsonophagocytosis of GAS, we first constructed a set of truncated M5 protein variants and expressed them on the surface of a homologous M‐negative GAS strain. Binding experiments with the resulting strains demonstrated that the major FH–FHL‐1 binding is located in a 42‐amino‐acid region within the N‐terminal third of M5. Measurement of bacteria‐bound complement factor C3 after incubation in plasma showed that the presence of this region had little impact upon complement deposition through the alternative pathway. Moreover, streptococci expressing M5 proteins lacking the major FH and FHL‐1 binding sequence resisted phagocytosis in human blood as efficiently as bacteria expressing the wild‐type protein. Consequently, the data suggest that the binding of the regulators of the alternative pathway is of limited importance for GAS phagocytosis resistance.