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KMID : 0903520060490040281
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Journal of the Korean Society of Agricultural Chemistry and Biotechnology
2006 Volume.49 No. 4 p.281 ~ p.286
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Inhibitory Effect of Zn2+ on Tolaasin-induced Hemolysis
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Cho Kwang-Hyun
Kim Sung-Tae
Kim Young-Kee
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Abstract
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Tolaasin, a pore-forming toxin, is a 1,985 Da peptide produced by Pseudomonas tolaasii and causes a brown blotch disease on cultivated mushrooms. Tolaasin forms pores on the plasma membrane of various cells including fungi, bacteria, plant as well as erythrocytes, and destroys cell structure. Zn2+ has been known to block the tolaasin activity by an unknown mechanism. Thus, we investigated the inhibitory effects of Zn2+ on the tolaasin-induced hemolysis to understand the molecular mechanism of tolaasin-induced pore formation. Zn2+ and Cd2+ inhibited the tolaasin-induced hemolysis in a dosedependent manner and their Ki values were 170 μM and 20 mM, respectively. The effect of Zn2+ was reversible since the subsequent addition of EDTA chelates Zn2+ and removes the inhibitory effect of Zn2+. When an osmotic protectant, PEG 2000, was added, the tolaasin-induced hemolysis was not observed. After the removal of osmotic protectant by centrifugation, resuspended erythrocytes with fresh medium were immediately hemolyzed, while the addition of Zn2+ prevented from hemolysis, implying that tolaasin-induced pores on the membrane were already formed in the medium containing osmotic protectant. These results suggest that Zn2+ inhibits the activity of tolaasin pores and it has minor effects on the membrane binding of tolaasin and the formation of pore.
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KEYWORD
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brown blotch disease, hemolysis, pore-forming toxin, Pseudomonas tolaasii, tolaasin, Zn2+
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