第六类分泌系统退化加速肠道上皮细胞死亡在大肠杆菌O157:H7 Escherichia coli
Zhibin Sun1,2,3, Chao Dong4, Pengcheng Zhou1,3
1State Key Laboratory Cultivation Base of Research, Prevention and Treatment for Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China.
PLoS pathogens
|March 3, 2026
概括
肠出血性大肠杆菌 (EHEC) 进化是通过失去VI型分泌系统 (T6SS) 功能,在获得prophage (Φstx2) 后. 这种退化增强了毒性因子的表达,增加了细胞毒性和疾病潜力.
科学领域:
- 微生物学 微生物学
- 细菌病原体的产生
- 进化生物学 进化生物学
背景情况:
- 第六类分泌系统 (T6SS) 是许多细菌的关键毒性因素.
- 肠出血性大肠杆菌 (EHEH) O157:H7是一种重要的人类病原体.
- 在EHEC中存在多种菌体,包括Shiga毒素转换菌体 (Φstx2).
研究的目的:
- 为了比较EHEC与其祖先菌株,大肠杆菌O55:H7 (aEPEC) 之间的T6SS基因集群.
- 调查T6SS突变对EHEC毒性的功能影响.
- 在EHEC中阐明T6SS退化和Fstx2集成之间的进化关系.
主要方法:
- 对T6SS基因集群进行比较基因组分析.
- 在蛋白质编码区域预测突变位置的序列分析.
- 功能性测试以评估T6SS分泌活性和细菌细胞毒性.
- 试管体诱导和删除实验.
主要成果:
- 在EHEC T6SS基因群中确定了26个突变位点,表明了退行趋势.
- 在TSSM基因中的特定插入显著损害了T6SS功能.
- T6SS无活化增强了EHEC细胞毒性和上皮细胞死亡,部分是通过促进Fstx2表达.
- 似乎T6SS退化与Fstx2集成有关,并增强主要毒性因子的激活.
结论:
- EHEC从一个祖先的aEPEC菌株进化,通过获得 Φstx2 和随后的T6SS. degeneration.
- T6SS退化是高度细胞毒性EHEC菌株进化的关键阶段.
- 这种进化路径突出显示了细菌病变发生过程中,菌体获取和宿主相互作用系统之间的相互作用.
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