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首页> 外文期刊>Infection and immunity >Shiga Toxin 2 Is Specifically Released from Bacterial Cells by Two Different Mechanisms
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Shiga Toxin 2 Is Specifically Released from Bacterial Cells by Two Different Mechanisms

机译：志贺毒素2是通过两种不同的机制从细菌细胞中特异性释放的

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Shiga toxin 1 (Stx1) is located in the periplasmic fraction, while Stx2 is found in the extracellular fraction, suggesting that enterohemorrhagic Escherichia coli (EHEC) contains a specific Stx2 release system. Both stx1 and stx2 are found within the late operons of Stx-encoding phages. Stx2 production is greatly induced by mitomycin C, suggesting that stx2 can transcribe from the late phage promoter of the Stx2-encoding phage. However, the Stx1 promoter adjacent to stx1 is a dominant regulatory element in Stx1 production. With the deletion of phage lysis genes of the Stx2-encoding phage, Stx2 remains in the bacterial cells. Further, we demonstrate that the Stx2-encoding phage, but not the Stx1-encoding phage, is spontaneously induced at extremely low rates. These results indicate that spontaneously specific Stx2-encoding phage induction is involved in specific Stx2 release from bacterial cells. Furthermore, to examine whether another system for specific Stx2 release is present in EHEC, we analyze the stx-replaced mutants. As expected, Stx2 derived from the Stx1 promoter is located in both the extracellular and cell-associated fractions, while mutant Stx2 (B subunit, S31N) derived from the Stx1 promoter is found only in the cell-associated fraction. These results indicate that EHEC has another Stx2 release system that strictly recognizes the serine 31 residue of the B subunit. Overall, we present evidence that specific Stx2 release from bacterial cells is involved in both the Stx2-encoding phage induction system and another Stx2 release system.
机译：志贺毒素1（Stx1）位于周质部分，而Stx2位于细胞外部分，表明肠出血性大肠埃希菌（EHEC）包含特定的Stx2释放系统。在Stx编码噬菌体的晚期操纵子中发现了 stx 1 和 stx 2 。丝裂霉素C极大地诱导了Stx2的产生，这表明 stx 2 可以从编码Stx2的噬菌体的晚期噬菌体启动子转录。然而，与 stx 1 相邻的Stx1启动子是Stx1生产中的主要调控元件。随着编码Stx2的噬菌体的噬菌体裂解基因的缺失，Stx2保留在细菌细胞中。此外，我们证明了以极低的速率自发诱导了Stx2编码噬菌体，而不是Stx1编码噬菌体。这些结果表明自发特异性编码Stx2的噬菌体诱导与细菌细胞中特异性Stx2的释放有关。此外，要检查EHEC中是否存在另一个用于特定Stx2释放的系统，我们分析了 stx 替换的突变体。正如预期的那样，源自Stx1启动子的Stx2位于细胞外和细胞相关部分，而源自Stx1启动子的突变型Stx2（B亚基，S31N）仅存在于细胞相关部分。这些结果表明，EHEC具有另一个Stx2释放系统，该系统严格识别B亚基的丝氨酸31残基。总的来说，我们提供证据表明细菌细胞中特定的Stx2释放参与了Stx2编码噬菌体诱导系统和另一个Stx2释放系统。

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