The thermostable direct hemolysin of Vibrio parahaemolyticus is a pore-forming toxin.
The hemolytic mechanism of thermostable direct hemolysin (TDH), a possible virulence factor of Vibrio parahaemolyticus, was studied. We demonstrated that TDH acts as a "pore-forming toxin" in temperature-dependent and -independent steps. The first temperature-dependent step requires only about 1-2 min incubation at 37 degrees C and makes a "pore" with a functional diameter of approximately 2 nm. The pore size was deduced from the molecular diameter of the colloidal inhibitory polysaccharides. The formation of the pores on TDH-treated erythrocyte membranes was also demonstrated by electron microscopic examination. The second step, which is a temperature-independent lytic step, causes the erythrocytes to swell owing to a colloidal osmotic influx of water via the "pores" into cells, resulting in erythrocyte lysis (or rupture) owing to increased intracellular pressure.
Honda
T
T
Research Institute for Microbial Diseases, Osaka University, Japan.
Ni
Y
Y
Miwatani
T
T
Adachi
T
T
Kim
J
J
D004912:Erythrocytes / Q000187:drug effects / Q000648:ultrastructure; D005759:Gastroenteritis / Q000209:etiology; D006460:Hemolysin Proteins / Q000633:toxicity*; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D013696:Temperature; D014736:Vibrio parahaemolyticus / Q000472:pathogenicity*; D014774:Virulence
D006460:Hemolysin Proteins