合成酶和酶的特异性集体排除了2'-脱氧氨从细菌警报剂中的特异性
Rich W Zhou1, Isis J Gordon1, Yuanyuan Hei1
1Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
bioRxiv : the preprint server for biology
|January 23, 2024
概括
细菌严格排除了2-deoxyguanosine警报器,因为它们的降解机制,如SpotT酶,是低效的. 这确保了细胞对饥饿的适当反应,通过防止这些异常信号分子的有害积累.
科学领域:
- 细菌生理学 细菌生理学
- 分子生物学分子生物学
- 生物化学 生物化学
背景情况:
- 细菌在饥饿期间合成警报器 (p) pGpp,以调节生长和生存.
- 激素合成酶对2'-脱氧氨酸 (2dG) 核酸具有高度选择性.
- 在细胞中,dGTP的度明显低于GTP.
研究的目的:
- 为了调查2dG激素的产生是有害的假设.
- 了解2dG核酸在警报信号中严格排除2dG核酸的酶基础.
- 为了阐明由酸酶降解激素降解的机制.
主要方法:
- 警报激素合成酶SasB的酶动力学 (kcat/KM) 使用GDP与dGDP.
- 比较化学蛋白质组学,以评估警报蛋白结合蛋白的歧视.
- 酶分析测量通过SpotT测量ppGpp和pp(dG) pp的水解速率.
- 对Spot的pyrophosphohydrolase活性进行金属依赖研究.
主要成果:
- 对GDP而言,SasB的特异性是GDP的65,000倍.
- 大多数大肠杆菌中的警报激素结合蛋白不能区分ppGpp和ppgpp.
- 斯波特酸酶降解pp ((dG) pp比ppGpp慢1000倍,这是警报剂酸酶的共同特征.
- SpoT是一种双核金属氧化基酸酶,对两个基质都有Mn2+的依赖性.
- ppGpp的2'-OH组对于协调Mn2+和稳定水解活性构成至关重要.
结论:
- 由于低效的降解机制,细菌严格排除了2dG核酸从警报激素合成中.
- 2'-OH 组在激素化酶的催化机制中起着至关重要的作用.
- 由于无法有效降解2dG警报,因此必须排除它们以防止有害的生理效应.
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