形态无活化的核糖酶的光化学救援
Brandon L Greene1, JoAnne Stubbe, Daniel G Nocera1
1Department of Chemistry and Chemical Biology , Harvard University , Cambridge , Massachusetts 02138 , United States.
Journal of the American Chemical Society
|October 23, 2018
概括
一级核酸减少酶 (RNR) 的活性依赖于子单元之间的基因转移 (RT). 一个特定的突变 (E350X) 阻止了这一点,但光化学救援揭示了E350
科学领域:
- 生物化学
- 酵素学
- 结构生物学
背景情况:
- 大肠杆菌中的Ia类核糖缩酶 (RNR) 在β2子单元中利用稳定的铁基 (Y122•).
- 从Y122• 转移到α2亚单元中的半氨酸残留物 (C439) 对于RNR活性至关重要,涉及氧化还原活性氨基酸的通路.
- 在α2β2接口的突变,如β2中的E350X,会破坏RT和RNR活动,但E350的调节作用的确切机制尚不清楚.
研究的目的:
- 阐明大肠杆菌Ia类RNRβ2亚单元中的谷氨酸-350 (E350) 控制基因转移 (RT) 的机制.
- 调查E350在RNR活动中必不可少的α2和β2子单元之间调节的作用.
主要方法:
- 使用E350Q-photoβ2构造以光化学诱导Y356的基质形成.
- 采用照片救援方法绕过最初的Y122•减少步骤并启动RT.
- 分析了光化学基生成对后续RT途径和整体RNR活动的影响.
主要成果:
- 在E350Q突变体中对Y356的光化学诱导恢复了RNR活性,从而绕过了Y122的减少.
- E350Q突变阻止了从Y122•开始的基因转移,但并没有阻碍下游RT路径的忠实性.
- 这些发现强烈地表明,E350是所有菌信号的关键媒介.
结论:
- 通过促进从Y122•转移基的形状变化,E350在基调节中起着关键作用.
- E350残留物对于α2和β2子单元之间传输调节信息至关重要,从而控制RNR酶活性.
- 这项研究提供了对Ia类RNR中的基因转移的全质控制的机制性见解.
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