Mega assemblages of oligomeric aerolysin-like toxins stabilized by toxin-associating membrane proteins.
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.
Department of Bioscience and Bioinfomatics, Kyushu Institute of Technology, Iizuka, Fukuoka 820-8502, Japan.
Hiroyasu
H
Shimada
Sakae
S
Kitada
D000818:Animals; D001427:Bacterial Toxins / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D004285:Dogs; D004731:Endotoxins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008970:Molecular Weight; D052899:Pore Forming Cytotoxic Proteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011489:Protein Denaturation; D055503:Protein Multimerization; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry
D001427:Bacterial Toxins; D004731:Endotoxins; D008565:Membrane Proteins; D052899:Pore Forming Cytotoxic Proteins; C515506:parasporin-2, Bacillus thuringiensis; D012967:Sodium Dodecyl Sulfate; C032676:aerolysin