在大肠杆菌II型Bcs分泌系统中的合成酶激活和纤维素修饰的结构基础
Itxaso Anso1,2,3, Samira Zouhir1,2,4, Thibault Géry Sana1,2
1Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600, Pessac, France.
Nature communications
|October 11, 2024
概括
这项研究揭示了细菌纤维素分泌 (Bcs) 系统如何招募和稳定聚合物修饰和调节的关键蛋白质. 通过代理激活机制允许纤维素合成,即使周期性迪加尼酸盐 (c-di-GMP) 含量低.
科学领域:
- 微生物学 微生物学
- 结构生物学 结构生物学
- 生物化学 生物化学
背景情况:
- 细菌纤维素 (BC) 是一种重要的生物膜矩阵外聚糖.
- BC合成依赖于复杂的细菌纤维素分泌 (Bcs) 系统.
- 这些系统由循环迪加尼酸盐 (c-di-GMP) 调节,涉及多种不同的蛋白质子单元.
研究的目的:
- 阐明大肠杆菌中BCS系统组装和调节的分子机制.
- 了解参与纤维素修饰和分泌的关键BCS子单元的招募和稳定.
- 研究BcsE作为二级c-di-GMP传感器在调节Bcs活动中的作用.
主要方法:
- 使用冷电子显微镜 (cryo-EM) 来确定高分辨率结构.
- 结构分析侧重于BcsG的BcsA依赖性招聘和BcsE2R2Q2复合物的BcsF依赖性招聘.
- 生物化学试验用于评估BcsE与c-di-GMP的结合及其与BcsRQ的相互作用.
主要成果:
- 结冷EM检测显示了三元BcsG pEtN转移酶的BcsA依赖性招募和二维BcsE2R2Q2调控复合物的BcsF依赖性招募.
- 作为二次c-di-GMP传感器,BCSE可以结合二核酸并稳定合成酶上必不可少的BCSRQ合作伙伴,而不依赖于直接的c-di-GMP-合成酶复合.
- 这种稳定机制降低了Bcs合成酶的激活值,即使在低细胞内c-di-GMP的情况下,也可以实现活性.
结论:
- 这项研究为大肠杆菌Bcs系统的结构组织和调节提供了原子层面的见解.
- 涉及BcsE的"代理激活"机制允许在不同的c-di-GMP条件下有效分泌纤维素.
- 这种调节策略在其他多糖分泌系统中得到保留,突出了微生物生理学的共同原则.
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