Thermostable direct hemolysin of Vibrio parahaemolyticus is a bacterial reversible amyloid toxin
Thermostable direct hemolysin of Vibrio parahaemolyticus is a bacterial reversible amyloid toxin
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DOI：
10.1021/bi050311s
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发表时间：
2005-07-26
期刊：
影响因子：
2.9
通讯作者：
Yanagihara, I
中科院分区：
文献类型：
--
作者：
Fukui, T;Shiraki, K;Yanagihara, I
热稳定直接溶血素（TDH）是副溶血弧菌的主要毒力因子，在60-70 ℃加热可解毒，但在80 ℃以上加热可重新激活。这种矛盾的现象，被称为阿克里乌斯效应，在近100年的时间里一直无法解释。我们现在证明这种效应与产生原纤维的蛋白质的结构变化有关。天然TDH（TDHn）通过在60 ° C下孵育转化成富含β链的无毒原纤维（TDHi）。TDH 1原纤维通过进一步加热到80 ℃以上（TDHu）解离成未折叠状态。TDHu的快速冷却导致蛋白质重折叠成毒性TDHn，而蛋白质通过TDHu的缓慢冷却被捕获在TDHi结构中。透射电子显微镜显示TDHi的纤维状结构。原纤维显示出成核依赖性伸长的性质和其硫磺素T荧光的增加。在含有神经节苷脂G（TIb）（一种假定的TDH受体）的脂质囊泡存在下，也观察到TDH富P结构的形成。发现刚果红以剂量依赖性方式抑制TDH的溶血活性。这些数据揭示了Arrhenius效应的机制与TDH的成纤性密切相关。
Thermostable direct hemolysin (TDH), a major virulence factor of Vibrio parahaemolyticus, is detoxified by heating at similar to 60-70 degrees C but is reactivated by additional heating above 80 degrees C. This paradoxical phenomenon, known as the Arrhenius effect, has remained unexplained for similar to 100 years. We now demonstrate that the effect is related to structural changes in the protein that produce fibrils. The native TDH (TDHn) is transformed into nontoxic fibrils rich in beta-strands by incubation at 60 degrees C (TDHi). The TDHi fibrils are dissociated into unfolded states by further heating above 80 degrees C (TDHu). Rapid cooling of TDHu results in refolding of the protein into toxic TDHn, whereas the protein is trapped in the TDHi structure by slow cooling of TDHu. Transmission electron microscopy indicates the fibrillar structures of TDHi. The fibrils show both the property of the nucleation-dependent elongation and the increase in its thioflavin T fluorescence. Formation of P-rich structures of TDH was also observed in the presence of lipid vesicles containing ganglioside G(TIb), a putative TDH receptor. Congo red was found to inhibit the hemolytic activity of TDH in a dose-dependent manner. These data reveal that the mechanism of the Arrhenius effect which is tightly related to the fibrillogenicity of TDH.