Mechanism of haemolysis by Vibrio vulnificus haemolysin.
The haemolytic action of Vibrio vulnificus haemolysin (VVH) was compared to that of streptolysin O (SLO). Both were cholesterol-binding haemolysins, but differed in the release of haemoglobin (Hb). In the first step of haemolysis, the haemolysins were temperature-independently bound to the cholesterol site on the target erythrocyte membrane. This was followed by the rapid release of K+, which is an intra-erythrocyte marker. Hb was then released, in different ways. In the case of VVH, Hb was released slowly after a relatively long lag, whereas with SLO, Hb was released as rapidly as K+. Haemolysis by VVH was inhibited by the addition of 30 mM-dextran 4 (mean Mr 4000), which is considered to be an effective colloid-osmotic protectant. The results therefore indicated that haemolysis by VVH (like that by Escherichia coli alpha-haemolysin and Staphylococcus aureus alpha-toxin) was caused by a colloid-osmotic mechanism. Both K+ and Hb release caused by VVH proceeded temperature-dependently, and the membrane fluidity of liposomes prepared with lipids extracted from sheep red blood cell membranes increased above 20 degrees C. These results suggest that the temperature-dependence of the haemolysis by VVH is due to the requirement for an increase in the membrane fluidity during the formation of a transmembrane pore.
Yamanaka
H
H
Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Satoh
T
T
Katsu
T
T
Shinoda
S
S
D006454:Hemoglobins / Q000378:metabolism; D006460:Hemolysin Proteins / Q000378:metabolism*; D006461:Hemolysis; D008560:Membrane Fluidity; D009996:Osmotic Fragility; D011188:Potassium / Q000378:metabolism; D014733:Vibrio / Q000378:metabolism*
D006454:Hemoglobins; D006460:Hemolysin Proteins; D011188:Potassium