半氨酸甲基化破坏了NF-κB激活中的泛素链传感
Li Zhang1, Xiaojun Ding, Jixin Cui
1Graduate Program in Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
Nature
|December 14, 2011
概括
肠病原性大肠杆菌NleE通过甲基化TAB2和TAB3蛋白质来阻断宿主免疫反应,这些蛋白质对NF-κB信号传递至关重要. 这种细菌效应剂使关键的无素链结合不活化,在感染期间破坏先天免疫力.
科学领域:
- 微生物学 微生物学
- 免疫学 免疫学 免疫学
- 分子生物学分子生物学
背景情况:
- 核因子kappa B (NF-κB) 信号传递对于对微生物病原体的天生的免疫力至关重要.
- 细菌感染,特别是肠病原性大肠杆菌,可以抑制NF-κB信号通路.
- 细菌调节在感染期间NF-κB激活中全素链信号特异性的精确机制在很大程度上仍未被探索.
研究的目的:
- 调查细菌病原体如何调节NF-κB激活中全素链信号特异性的研究.
- 为了确定在感染期间阻断NF-κB信号传递的细菌因素和宿主目标.
- 阐明肠病原性大肠杆菌抑制宿主NF-κB反应的分子机制.
主要方法:
- 研究了肠病原性大肠杆菌三型分泌效应因子NleE与宿主蛋白TAB2和TAB3之间的相互作用.
- 使用S-adenosyl-l-methionine描述了NleE的酶活性,并确定了其基质特异性.
- 利用蛋白质截断,宫外表达和位点定向突变发生来评估NleE介导甲基化对TAB2和TAB3功能和NF-κB激活的影响.
主要成果:
- 肠病原性大肠杆菌NleE直接使人体TAB2和TAB3无活化,这是NF-κB信号传输中的关键无素链感应蛋白.
- NleE具有S-adenosyl-l-methionine依赖的甲基转移酶活性,特别是在TAB2和TAB3的Npl4指 (NZF) 域中甲基化氨酸残留物.
- TAB2-NZF和TAB3-NZF域的甲基化导致离子损失,并取消了全方位链结合活性,从而抑制了NF-κB信号传递.
- 宿主细胞中TAB2和TAB3的NleE介导的甲基化降低了它们的基链结合能力.
- 将TAB3 NZF域替换为甲基化不敏感的变体,使NF-κB激活对NleE具有抗性.
结论:
- 来自肠病原性大肠杆菌的细菌效应剂NleE采用一种新的甲基化策略来破坏宿主NF-κB的先天免疫信号传递.
- 细菌甲基转移酶对指氨酸残留物的修饰代表了调节真核细胞通路的保存机制,包括NF-κB.
- 了解这种细菌对宿主无处不在机制的操纵,可以了解宿主-病原体相互作用和潜在的治疗点.
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