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在结构上,Gcn2模仿了HisRS酶,并在功能上重新定位了HisRS酶,用于整合应激反应
Charles Bou-Nader1, Swati Gaikwad2, Soheila Bahmanjah1
1Laboratory of Molecular Biology, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
概括
蛋白激酶Gcn2的激活依赖于其基-tRNA合成酶 (HisRS) 域. 结构模拟揭示了脱糖的tRNA如何结合这个域,将酶重新用于新的调节功能.
科学领域:
- 分子生物学分子生物学
- 生物化学 生物化学
- 结构生物学 结构生物学
背景情况:
- 蛋白激酶Gcn2在氨基酸饥饿期间调节蛋白质合成.
- Gcn2的激活涉及它的histidyl-tRNA合成酶 (HisRS) 域,tRNA结合作为一个拟议的机制.
- 核糖体P-茎蛋白也涉及作为替代Gcn2激活剂.
研究的目的:
- 阐明通过tRNA激活Gcn2的结构基础.
- 研究HisRS域在Gcn2的监管功能中的作用.
- 了解新陈代谢酶是如何重新用于新的调节作用的.
主要方法:
- 在* Chaetomium热* Gcn2 HisRS域的X射线晶体学.
- 结构分析揭示了HisRS催化和抗结合域的模仿性.
- 在酵母中的保存残留物的突变分析 Gcn2.2.
主要成果:
- 在结构上,Gcn2 HisRS域模仿了真实HisRS.的催化 (CD) 和抗结合 (ABD) 域.
- Gcn2 HisRS 域缺乏氨基化活性,这表明它用于酶激活.
- 关键的ABD残留物或ABD-CD接口的突变会损害饥饿细胞中的Gcn2功能.
结论:
- 脱氧化tRNA可能通过模仿tRNA结合位点与其HisRS域结合来激活Gcn2.
- Gcn2 HisRS 域已从其祖先的代谢功能中重新配置,以调节新的调节控制.
- 这项研究为tRNA介导的Gcn2激活和酶重定位提供了结构基础.
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