通过循环核酸结合激活Csm6核核糖酶:在紧急情况下,扭转以打开
Stuart McQuarrie1, Januka S Athukoralage1, Stephen A McMahon1
1Biomedical Sciences Research Complex, School of Biology, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
Nucleic acids research
|September 25, 2023
概括
第三类CRISPR系统使用循环氧基酸 (cOA) 来激活Csm6核核糖酶以防御细菌. 这项研究揭示了cA6如何与Csm6结合.
科学领域:
- 分子生物学分子生物学
- 生物化学 生化学
- 结构生物学 结构生物学
背景情况:
- 第三类CRISPR系统通过合成循环橄基酸盐 (cOA) 第二信使来提供对移动遗传元素 (MGE) 的适应性免疫力.
- cOA激活了与CRISPR相关的核酶,包括Csm6核核酶,这些核酶具有CARF域用于cOA结合,并具有核酸裂变的融合HEPN核核核酶域.
- Csm6酶对细菌防御至关重要,并且越来越多地用于核酸检测测定,但它们的激活机制仍然不完全理解.
研究的目的:
- 阐明Streptococcus thermophilus中Csm6'核糖核酶在结合循环六甲基酸盐 (cA6) 时的激活机制.
- 描述cA6介导的Csm6'核糖核酶活性激活的结构基础.
主要方法:
- 采用X射线结晶学来确定Csm6'在非活性和cA6结合的活性状态中的结构.
- 来自Streptococcus thermophilus的csm6'核糖核酶的生物化学表征.
主要成果:
- 晶体结构在cA6结合时显示出显著的形状变化,包括CARF和HEPN域之间的~60°旋转.
- 6H域充当关键链接器,将cA6诱导的形状变化从CARF域传递到HEPN域.
- 激活包括在HEPN域内重新定位活性部位残留物,导致mRNA破坏.
结论:
- 该研究提供了通过cA6.6激活csm6'核糖核酶的详细结构机制.
- 了解这种激活机制对于优化基于Csm6的诊断工具和利用CRISPR免疫力用于生物技术应用至关重要.
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