Physical characterization of the pore forming cytolysine from Gardnerella vaginalis.
The cytolytic toxin (CTox) produced by Gardnerella vaginalis is able to form voltage-dependent cationic channels when incorporated in lipid membranes (Moran et al. (1991) FEBS Lett. 283, 317-320). Osmotic protection experiments show that toxin incorporated in human erythrocytes forms pores between 18 A and 28 A in diameter. A hypothesis of pore formation as a primary event to produce cytolysis is proposed. The CTox activity increases when cells are depolarized by increasing the extracellular K+ concentration, probably reflecting the voltage dependent character of CTox formed channels. The cytolytic effect of the toxin was prevented by low temperatures and was a function of the extracellular Ca2+ concentration, suggesting a Ca2+ influx as part of the lytic mechanism. Binding of CTox to erythrocytes was dependent on external Ca2+ and was less temperature-dependent. Dose-response analysis suggests cooperativity of the toxin for the lytic activity, although no direct evidence of oligomerization has been found.
Moran
O
O
Settore di Biofisica, SISSA, Trieste, Italy.
Zegarra-Moran
O
O
Virginio
C
C
Gusmani
L
L
Rottini
G D
GD
D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects*; D003603:Cytotoxins / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004910:Erythrocyte Membrane / Q000737:chemistry; D006194:Gardnerella vaginalis / Q000472:pathogenicity*; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D007473:Ion Channels / Q000187:drug effects*; D009994:Osmolar Concentration; D013696:Temperature
D003603:Cytotoxins; D007473:Ion Channels; D002118:Calcium