Molecular principles of translation termination

描述(申请人提供)：所有生物体的翻译都是由核糖体完成的，核糖体是最古老和普遍保守的分子机器之一。末端终止是蛋白质合成的最后一步，它确保表达的蛋白质具有由相应的开放阅读框架严格定义的长度。这一关键步骤应该是准确和有效的，以防止截短或过长的多肽产品积累，这可能会对细胞产生毒性。虽然大多数翻译步骤和相应的体外因子(如延伸因子)在细菌和真核生物之间高度保守，但翻译的终止不是这样。在人类中，早产与大量的遗传性疾病有关。这些独特的特征使终止治疗成为药物开发的一个有前途的目标。对细菌翻译终止的详细了解可能会为我们开发抗菌药物提供工具。阐明真核终止的分子机制对于设计或寻找针对与过早终止相关的人类神经系统疾病的治疗方法是必要的。在这项提案中，我们将深入了解细菌和真核生物中终止的分子机制。在目标1中，我们将确定细菌70S核糖体上终止的中间构象步骤的晶体结构。这将为细菌释放因子RF1和RF2如何实现非凡的准确性提供洞察力。在目标2中，我们将研究真核细胞80S核糖体的终止。这里涉及到必需的I类释放因子eRF1和II类释放因子eRF3，它们在结构上与细菌对应物不同。在目标3中，我们将探索针对早产引起的疾病的新的治疗途径。我们研究的长期目标是对涉及翻译的关键细胞过程获得详细的机械洞察力，并为治疗学的发展做出贡献。

DESCRIPTION (provided by applicant): Translation in all organisms is performed by the ribosome, one of the most ancient and universally conserved molecular machines. Termination is the last step of protein synthesis, which ensures that expressed proteins have lengths strictly defined by the corresponding open reading frames. This critical step should be accurate and efficient to prevent accumulation of truncated or overly long polypeptide products that can be toxic to cell. Whereas most steps of translation and corresponding extraribosomal factors (e.g. elongation factors) are highly conserved between bacteria and eukaryotes, the termination of translation is not. In human, premature termination is associated with a large number of genetic diseases. These unique features place termination as a promising target for development of drugs. A detailed understanding of bacterial translation termination may provide us with tools to develop antibacterial drugs. Elucidation of the molecular mechanism of eukaryotic termination is necessary to design or search for therapeutics to target human neurological diseases linked to premature termination. In this proposal, we will gain insights into molecular mechanisms of termination in both bacteria and eukaryotes. In Aim 1, we will determine crystal structures of intermediate conformational steps of termination on the bacterial 70S ribosome. This will provide insights into how a remarkable accuracy is achieved by bacterial release factors RF1 and RF2. In Aim 2, we will study termination on the eukaryotic 80S ribosome. Here, essential class I release factor eRF1 and class II release factor eRF3 are involved, which are structurally distinct from their bacterial counterparts. In Aim 3, we will explore new therapeutic routes against diseases caused by premature termination. The long-term goals of our studies are to gain detailed mechanistic insights into key cellular processes involving translation, and to contribute to therapeutics development.