Thermostable Direct Hemolysin of Vibrio parahaemolyticus Is a Bacterial Reversible Amyloid Toxin
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- 作者：Takashi Fukui ; Kentaro Shiraki ; Daizo Hamada ; Kojiro Hara ; Tomoko Miyata ; Shinsuke Fujiwara ; Kouta Mayanagi ; Keiko Yanagihara ; Tetsuya Iida ; Eiichiro Fukusaki ; Tadayuki Imanaka ; Takeshi Honda ; and Ita
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：July 26, 2005
- 年：2005
- 卷：44
- 期：29
- 页码：9825 - 9832
- 全文大小：350K
- 年卷期：v.44,no.29(July 26, 2005)
- ISSN：1520-4995
文摘
Thermostable direct hemolysin (TDH), a major virulence factor of Vibrio parahaemolyticus,is detoxified by heating at ~60-70 
C but is reactivated by additional heating above 80 C. This paradoxicalphenomenon, known as the Arrhenius effect, has remained unexplained for ~100 years. We nowdemonstrate that the effect is related to structural changes in the protein that produce fibrils. The nativeTDH (TDHn) is transformed into nontoxic fibrils rich in 
-strands by incubation at 60 C (TDHi). TheTDHi fibrils are dissociated into unfolded states by further heating above 80 C (TDHu). Rapid coolingof TDHu results in refolding of the protein into toxic TDHn, whereas the protein is trapped in the TDHistructure by slow cooling of TDHu. Transmission electron microscopy indicates the fibrillar structures ofTDHi. The fibrils show both the property of the nucleation-dependent elongation and the increase in itsthioflavin T fluorescence. Formation of -rich structures of TDH was also observed in the presence oflipid vesicles containing ganglioside GT1b, a putative TDH receptor. Congo red was found to inhibit thehemolytic activity of TDH in a dose-dependent manner. These data reveal that the mechanism of theArrhenius effect which is tightly related to the fibrillogenicity of TDH.
C but is reactivated by additional heating above 80 C. This paradoxicalphenomenon, known as the Arrhenius effect, has remained unexplained for ~100 years. We nowdemonstrate that the effect is related to structural changes in the protein that produce fibrils. The nativeTDH (TDHn) is transformed into nontoxic fibrils rich in -strands by incubation at 60 C (TDHi). TheTDHi fibrils are dissociated into unfolded states by further heating above 80 C (TDHu). Rapid coolingof TDHu results in refolding of the protein into toxic TDHn, whereas the protein is trapped in the TDHistructure by slow cooling of TDHu. Transmission electron microscopy indicates the fibrillar structures ofTDHi. The fibrils show both the property of the nucleation-dependent elongation and the increase in itsthioflavin T fluorescence. Formation of -rich structures of TDH was also observed in the presence oflipid vesicles containing ganglioside GT1b, a putative TDH receptor. Congo red was found to inhibit thehemolytic activity of TDH in a dose-dependent manner. These data reveal that the mechanism of theArrhenius effect which is tightly related to the fibrillogenicity of TDH.