Mega assemblages of oligomeric aerolysin-like toxins stabilized by toxin-associating membrane proteins

J Biochem. 2011 Jan;149(1):103-15. doi: 10.1093/jb/mvq124. Epub 2010 Oct 22.


Most β pore-forming toxins need to be oligomerized via receptors in order to form membrane pores. Though oligomerizing toxins frequently form SDS-resistant oligomers, it was questionable whether SDS-resistant oligomers reflected native functional toxin complexes. In order to elucidate the essence of the cytocidal assemblages, oligomers of aerolysin-like toxins, aerolysin, parasporin-2 and epsilon toxin, were examined with or without SDS. On Blue Native PAGE, each toxin, which had been solubilized from target cells with mild detergent, was a much larger complex (nearly 1 MDa) than the typical SDS-resistant oligomers (∼200 kDa). Size exclusion chromatography confirmed the huge toxin complexes. While a portion of the huge complexes were sensitive to proteases, SDS-resistant oligomers resist the proteolysis. Presumably the core toxin complexes remained intact while the cellular proteins were degraded. Moreover, intermediate complexes, which included no SDS-resistant oligomers, could be detected at lower temperatures. This study provides evidence for huge functional complexes of β pore-forming toxins and emphasizes their potential variance in composition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Toxins / chemistry*
  • Bacterial Toxins / metabolism
  • Cell Line
  • Cells, Cultured
  • Dogs
  • Endotoxins / chemistry*
  • Endotoxins / metabolism
  • Humans
  • Membrane Proteins / chemistry*
  • Membrane Proteins / metabolism
  • Molecular Weight
  • Pore Forming Cytotoxic Proteins / chemistry*
  • Pore Forming Cytotoxic Proteins / metabolism
  • Protein Binding
  • Protein Denaturation
  • Protein Multimerization
  • Sodium Dodecyl Sulfate / chemistry


  • Bacterial Toxins
  • Endotoxins
  • Membrane Proteins
  • Pore Forming Cytotoxic Proteins
  • parasporin-2, Bacillus thuringiensis
  • Sodium Dodecyl Sulfate
  • aerolysin