A chimera of interleukin 2 and a binding variant of aerolysin is selectively toxic to cells displaying the interleukin 2 receptor.
Aerolysin is a bacterial toxin that binds to glycosylphosphatidylinositol-anchored proteins (GPI-AP) on mammalian cells and oligomerizes, inserting into the target membranes and forming channels that cause cell death. We have made a variant of aerolysin, R336A, that has greatly reduced the ability to bind to GPI-AP, and as a result it is only very weakly active. Fusion of interleukin 2 (IL2) to the N terminus of R336A-aerolysin results in a hybrid that has little or no activity against cells that do not have an IL2 receptor because it cannot bind to the GPI-AP on the cells. Strikingly, the presence of the IL2 moiety allows this hybrid to bind to cells displaying high affinity IL2 receptors. Once bound, the hybrid molecules form insertion-competent oligomers. Cell death occurs at picomolar concentrations of the hybrid, whereas the same cells are insensitive to much higher concentrations of R336A-aerolysin lacking the IL2 domain. The targeted channel-forming hybrid protein may have important advantages as a therapeutic agent.
Osusky
Milan
M
Protox Therapeutics Incorporated, Vancouver, British Columbia V6C 3E8, Canada.
Teschke
Lisa
L
Protox Therapeutics Incorporated, Vancouver, British Columbia V6C 3E8, Canada.
Wang
Xiaoying
X
Protox Therapeutics Incorporated, Vancouver, British Columbia V6C 3E8, Canada.
Wong
Kevin
K
Protox Therapeutics Incorporated, Vancouver, British Columbia V6C 3E8, Canada.
Buckley
J Thomas
JT
Protox Therapeutics Incorporated, Vancouver, British Columbia V6C 3E8, Canada. Electronic address: tbuckley@protoxtherapeutics.com.
D000818:Animals; D001427:Bacterial Toxins / Q000302:isolation & purification / Q000378:metabolism*; D016923:Cell Death; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D006461:Hemolysis / Q000187:drug effects; D006736:Horses; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism*; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D050505:Mutant Proteins / Q000378:metabolism*; D052899:Pore Forming Cytotoxic Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D011498:Protein Precursors / Q000302:isolation & purification / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D020836:Protein Structure, Quaternary; D015375:Receptors, Interleukin-2 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000633:toxicity*
D001427:Bacterial Toxins; D007376:Interleukin-2; D050505:Mutant Proteins; D052899:Pore Forming Cytotoxic Proteins; D011498:Protein Precursors; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins; C032676:aerolysin