Structure and function of pneumolysin, the multifunctional, thiol-activated toxin of Streptococcus pneumoniae

Mol Microbiol. 1991 Nov;5(11):2611-6. doi: 10.1111/j.1365-2958.1991.tb01969.x.


Pneumolysin is a thiol-activated, membrane-damaging, multifunctional toxin and a known virulence factor of Streptococcus pneumoniae. The toxin can interfere with the functioning of both cellular and soluble components of the human immune system which protects against pneumococcal infection. Different amino acids within the toxin which are important in promoting oligomerization of the toxin in membranes and for the generation of functional lesions have been identified by site-directed mutagenesis. Pneumolysin can also activate the classical pathway of complement, and this appears to involve antibody binding (via Fc) by a region of the toxin homologous to C-reactive protein, a human acute-phase protein also capable of classical pathway activation and implicated in host defence against pneumococcal infection.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacterial Proteins
  • C-Reactive Protein / genetics
  • Cell Membrane / drug effects
  • Complement Pathway, Classical / drug effects
  • Cysteine / physiology
  • Humans
  • Immunoglobulin Fc Fragments / metabolism
  • Mice
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Streptococcus pneumoniae / pathogenicity
  • Streptococcus pneumoniae / physiology*
  • Streptolysins / genetics
  • Streptolysins / pharmacology
  • Streptolysins / physiology*
  • Structure-Activity Relationship
  • Sulfhydryl Compounds / pharmacology
  • Virulence


  • Bacterial Proteins
  • Immunoglobulin Fc Fragments
  • Streptolysins
  • Sulfhydryl Compounds
  • plY protein, Streptococcus pneumoniae
  • C-Reactive Protein
  • Cysteine