The genetics of ribosomal reading frame maintenance

核糖体阅读框维持的遗传学

• 批准号: 7248501
• 负责人: Philip James Farabaugh
• 金额: $ 11.27万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE COUNTY
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-08-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7248501
• 关键词: Escherichia coli; Saccharomyces cerevisiae; chemical structure function; computer data analysis; frameshift mutation; fungal genetics; fungal proteins; genetic regulation; genetic translation; intermolecular interaction; mass spectrometry; messenger RNA; model design /development; nucleic acid hybridization; nucleic acid sequence; nucleic acid structure; physical model; polymerase chain reaction; ribosomal RNA; ribosomes; site directed mutagenesis; telomerase; transfer RNA; transposon /insertion element

DESCRIPTION (provided by applicant): Translation of mRNA sequences by the ribosome is normally a faithful process, yet mistakes occur. Sequences in mRNAs have evolved that modulate the accuracy of translation to increase the frequency of translational frameshifting errors. Such sites are termed programmed translational frameshift sites. The yeast Ty elements, a class of retrotransposons, express the enzymes needed for retrotransposition using a programmed+1 frameshifting mechanism. We find evidence that frameshifting occurs because the mRNA disrupts the function of the ribosomal accuracy center by inserting peptidyl-tRNAs into the ribosomal P site that Make a non-canonical interaction with the mRNA. The unusual codon*anticodon complex formed disrupts the ability of the ribosome to accurately recognize in-frame cognate tRNAs in the A site. Also, a sequence derived from the Ty3 retrotransposon appears to directly interact with a structure in the rRNA necessary for accurate decoding in the A site. This sequence, termed the Ty3 stimulator, appears to base pair with part of the loop of Helix 18. A nucleotide in that base paired region, G530, directly contacts both mRNA and tRNA nucleotides in the A site codon*anticodon complex to assure that they are correctly paired. By sequestering that nucleotide in an rnRNA*rRNA complex, the Ty3 stimulator could reduce overall discrimination in the A site. Recently, detailed molecular structures of the 30S, 50S and 70S ribosomes were solved. These structures provide an unprecedented level of detail about the structure of the ribosome, and can be used to predict the mechanisms used during translation, including the error correction mechanisms. The structures clearly show how cognate, in-frame tRNAs are recognized, but gives little direct information about how the ribosome avoids errors leading to changes in translational frame. Arguably, maintenance of frame is the most critical role for the ribosome, since frame errors almost always result in production of inactive protein products while missense errors rarely do. To address how the ribosome maintains reading frame we have been using the tools provided by the programmed translational frameshift sites. We will continue that work attempting to determine how error-correcting elements of the ribosome function in this process. Recently, we found that mRNA sequences that stimulate frame errors also induce errors during translational initiation. This suggests that the accuracy of these processes has shared aspects. We will use the twin tools afforded by frameshifting and translation initiation to dissect the ribosomal functions insuring accuracy.

描述（由申请人提供）： mRNA 序列的翻译 核糖体通常是一个忠实的过程，但也会出现错误。 mRNA 中的序列 已经进化出调节翻译的准确性以提高 平移移码错误的频率。此类网站被称为 程序化的翻译移码位点。酵母 Ty 元素，一类 逆转录转座子，使用逆转录转座子表达逆转录转座所需的酶 编程+1移码机制。我们发现移码的证据 发生的原因是 mRNA 破坏了核糖体精确中心的功能 通过将肽基-tRNA 插入核糖体 P 位点，形成非规范的 与 mRNA 的相互作用。不寻常的密码子*反密码子复合物形成破坏 核糖体准确识别框内同源 tRNA 的能力 A站点。此外，源自 Ty3 逆转录转座子的序列似乎 直接与 rRNA 中精确解码所需的结构相互作用 在A站点。该序列称为 Ty3 刺激子，似乎是碱基对 具有螺旋 18 的环的一部分。该碱基配对区域中的核苷酸， G530，直接接触A位点的mRNA和tRNA核苷酸 密码子*反密码子复合物以确保它们正确配对。经过 Ty3 刺激剂将该核苷酸隔离在 rnRNA*rRNA 复合物中 减少 A 位点的整体歧视。最近，详细的分子 30S、50S 和 70S 核糖体的结构已得到解决。这些结构 提供有关核糖体结构的前所未有的详细信息， 并可用于预测翻译过程中使用的机制，包括 纠错机制。这些结构清楚地表明了如何同源， 框内 tRNA 被识别，但很少提供关于如何识别的直接信息 核糖体避免了导致翻译框架变化的错误。可以说， 框架的维护是核糖体最关键的作用，因为框架 错误几乎总是导致无活性蛋白质产品的产生，而 错义错误很少发生。解决核糖体如何维持阅读框架 我们一直在使用程序翻译提供的工具 移码位点。我们将继续这项工作，试图确定如何 在此过程中核糖体功能的纠错元件。最近， 我们发现刺激帧错误的 mRNA 序列也会导致错误 在翻译起始期间。这表明这些数据的准确性 流程具有共享的方面。我们将使用提供的双工具 移码和翻译起始以剖析核糖体功能 保证准确性。