Physiological impact of reduced fidelity in protein synthesis

 描述（由申请人提供）：蛋白质合成是生命所有三个领域中基本且重要的过程。在过去的几十年里，生物化学、生物物理学和结构生物学的进步提高了我们对氨酰基-tRNA (aa-tRNA) 合成、翻译质量控制、肽延伸和核糖体解码分子机制的了解。然而，我们仍处于了解活细胞中蛋白质合成如何调节以及翻译调节如何影响不同生物体适应性的早期阶段。蛋白质错误翻译（翻译错误水平增加）已被证明会导致细菌生长缺陷、酵母线粒体功能障碍和哺乳动物神经变性。因此，人们普遍认为错误翻译对细胞有害，需要避免。令人惊讶的是，我们和其他人已经证明，在氧化应激和病毒感染期间，误译会增加，这导致最近有人提出误译可能在某些应激条件下发挥适应性作用。目前支持该模型的实验证据有限，并且对分子水平上的这些适应性机制知之甚少。这里的目标是定义细菌如何应对误译。具体来说，我们将 (a) 确定错误翻译使大肠杆菌适应过氧化物胁迫的机制； (b) 确定错误翻译对大肠杆菌中蛋白质聚集的影响； (c) 定义大肠杆菌中氧化应激引起的误译的作用。此类工作将揭示细菌在严重压力下生存的先前未知的适应性机制，并提高对新型翻译调控的认识，通过微调蛋白质合成的保真度来增强表型多样性和适应性。

 DESCRIPTION (provided by applicant): Protein synthesis is a fundamental and essential process in all three domains of life. In the past decades, advances in biochemistry, biophysics, and structural biology have improved our knowledge on the molecular mechanisms of aminoacyl-tRNA (aa-tRNA) synthesis, translational quality control, peptide elongation, and ribosomal decoding. However, we are still at a very early stage of understanding how protein synthesis is regulated in living cells and how translational regulation affects the fitness of different organisms. Protein mistranslation (an increased level of translational errors) has been shown to cause growth defects in bacteria, mitochondrial dysfunction in yeast, and neurodegeneration in mammals. It is therefore commonly accepted that mistranslation is harmful to cells and needs to be avoided. Surprisingly, we and others have shown that mistranslation is increased during oxidative stress and viral infection, leading to a recent proposal that mistranslation may play adaptive roles under certain stress conditions. Experimental evidence to support this model is currently limited, and little is known about these adaptive mechanisms at the molecular level. The objective here is to define how bacteria respond to mistranslation. Specifically, we will (a) determine the mechanism by which mistranslation adapts E. coli to peroxide stress; (b) determine the impact of mistranslation on protein aggregation in E. coli; and (c) define the role of mistranslation caused by oxidative stres in E. coli. Such work will reveal previously unknown adaptive mechanisms by which bacteria survive severe stresses, and improve the knowledge of a new class of translational regulation that enhances phenotypic diversity and fitness through fine-tuning fidelity of protein synthesis.