通过BREX抗菌素免疫系统识别外来DNA的分子基础
Alena Drobiazko1, Myfanwy C Adams2, Mikhail Skutel1
1Skolkovo Institute of Science and Technology, Moscow, Russia.
Nature communications
|February 20, 2025
概括
BREX (BacteRiophage EXclusion) 系统使用DNA甲基化进行菌体防御. BrxX蛋白与DNA结合并形成更大的复合体对于这种细菌免疫机制至关重要.
科学领域:
- 菌体生物学 菌体生物学
- 细菌免疫的分子机制
- 表观遗传调节 表观遗传调节
背景情况:
- 细菌菌体排斥 (BREX) 系统是抗菌体机制的超级家族.
- 这些系统利用特定站点的表观遗传DNA甲基化来区分宿主和外来DNA.
研究的目的:
- 阐明I型BREX系统在对菌体的细菌防御中的分子机制.
- 了解BrxX (PglX) 甲基转移酶在DNA识别和甲基化中的作用.
- 研究BREX免疫综合体的组合和调节.
主要方法:
- 低温电子显微镜 (cryo-EM) 用于确定与dDNA结合的BrxX的结构.
- BrxX的结构引导工程改变DNA特异性并增强菌体防御.
- 生物化学测试以评估BrxX活动和复杂形成.
主要成果:
- 确定了与目标dDNA结合的Escherichia coli BrxX的2.2-Å cryo-EM结构,揭示了详细的DNA识别.
- 工程设计的BrxX变种具有扩展的DNA特异性和显著增强的菌体防御能力.
- 证明 BrxX 单独不会甲基化 DNA,突出显示了超分子 BrxBCXZ 免疫复合物的必要性.
- 揭示了BrxX与菌体抑制剂Ocr结合的冷-EM结构,显示Ocr sequestrers BrxX在一个不活跃的二维形式.
结论:
- 在I型BREX系统中,BrxX蛋白对于DNA结合和甲基化至关重要,它使用S-adenosyl metionin作为辅助因子.
- 激活BREX防御需要组装BrxBCXZ免疫综合体,BrxX介导的外来DNA传感作为最初的步骤.
- 对BrxX-DNA和BrxX-Ocr相互作用的结构洞察力为了解和操纵BREX介导的细菌免疫提供了基础.
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