Detergent-resistant membranes are platforms for actinoporin pore-forming activity on intact cells.
Sticholysin II is a pore-forming toxin produced by the sea anemone Stichodactyla helianthus. We studied its cytolytic activity on COS-7 cells. Fluorescence spectroscopy and flow cytometry revealed that the toxin permeabilizes cells to propidium cations in a dose-dependent and time-dependent manner. This permeabilization is impaired by preincubation of cells with cyclodextrin. Isolation of detergent-resistant cellular membranes showed that sticholysin II colocalizes with caveolin-1 in fractions corresponding to raft-like domains. The interaction of sticholysin II with such domains is only lipid dependent as it also occurs in the absence of any other membrane-associated protein. Toxin binding to raft-like lipid vesicles inhibited cell permeabilization. The results suggest that sticholysin II promotes pore formation in COS-7 cells through interaction with membrane domains which behave like cellular rafts.
Alegre-Cebollada
Jorge
J
Departamento de Bioquímica, Facultad de Química, Universidad Complutense, Madrid, Spain.
Rodríguez-Crespo
Ignacio
I
Gavilanes
José G
JG
del Pozo
Alvaro Martínez
AM
D000818:Animals; D019556:COS Cells; D051242:Caveolin 1 / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry*; D002522:Chlorocebus aethiops; D003064:Cnidarian Venoms / Q000378:metabolism*; D003505:Cyclodextrins / Q000378:metabolism; D003902:Detergents / Q000737:chemistry*; D006460:Hemolysin Proteins / Q000378:metabolism*; D021962:Membrane Microdomains / Q000737:chemistry; D012615:Sea Anemones / Q000737:chemistry*
D051242:Caveolin 1; D003064:Cnidarian Venoms; D003505:Cyclodextrins; D003902:Detergents; D006460:Hemolysin Proteins; C404794:sticholysin II