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Complement activation and antibody binding by pneumolysin via a region of the toxin homologous to a human acute‐phase protein
Author(s) -
Mitchell T. J.,
Andrew P. W.,
Saunders F. K.,
Smith A. N.,
Boulnois G. J.
Publication year - 1991
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 - 10.1111/j.1365-2958.1991.tb00812.x
Subject(s) - pneumolysin , biology , complement system , toxin , microbiology and biotechnology , alternative complement pathway , antibody , genetics , streptococcus pneumoniae , antibiotics
Summary Pneumolysin, a membrane‐damaging toxin, is known to activate the classical complement pathway. We have shown that 1 μg ml −1 of pneumolysin can activate complement, which is a much lower level than observed previously. We have identified two distinct regions of pneumolysin which show homology with a contiguous sequence within acute‐phase proteins, including human C‐reactive protein (CRP). Site‐directed mutagenesis of the pneumolysin gene was used to change residues common to pneumolysin and CRP. Some of the modified toxins had a reduced ability both to activate complement and bind antibody. We suggest that the ability of pneumolysin to activate complement is related to its ability to bind the Fc portion of immunoglobulin G.