RNA Chemistry and the RNA World

RNA 化学和 RNA 世界

• 批准号: 238948-2013
• 负责人: Unrau, Peter
• 金额: $ 6.05万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=629971
• 关键词: RNA; Chemistry; World

The presence of RNA at the core of the ribosome, the extensive use of nucleotide cofactors, and the synthesis of DNA and some amino acids from RNA precursors suggests that RNA was once the dominant catalytic and genetic polymer early in the evolution of life. This 'RNA World' hypothesis assumes that RNA is capable of all the reactions required to maintain and evolve a 'ribo-organism'. One of my laboratories long term objectives is to select and evolve an RNA replicase ribozyme capable of sustaining RNA based evolution in the laboratory. Such a system could be called 'alive' and would marry the underlying simplicity of chemistry to the complexity of biology. Identifying the minimal complexity required to produce an RNA replicace would inform as never before about the difficulties faced on the early Earth in transitioning from an abiotic to biotic world. Aims I&II: Towards an RNA replicase ribozyme: We will use conventional and emulsion based in vitro selection methodologies to isolate superior RNA polymerase ribozymes that are highly processive. The current state of the art polymerase ribozyme is capable of rapid phosphodiester bond formation, but is nearly unable to appropriately hold the primer-template substrate it extends. Overcoming this central problem has the potential to increase polymerization rates by factors of ten or more and offers the prospect of extending a template by hundreds of nucleotides in a time scale measured in hours - an exciting prospect if realized! Aim II: Translocation mechanism & homopolymer polymerases: We will select for polymerase ribozymes that processively incorporate poly(A) tails onto the end of an RNA primer. Such polymerases are interesting as the processive synthesis of a long homopolymer requires a translocation mechanism that, after the incorporation of a nucleotide, must reset the polymerase complex to look exactly like the initial state so as to allow iterative polymerization. Such a mechanism ultimately could prove very useful in displacing a non-template strand during RNA replication and thus play an important role in developing a replicase ribozyme.

核糖体核心RNA的存在，核苷酸辅因子的广泛使用，以及从RNA前体合成DNA和一些氨基酸表明，在生命进化的早期，RNA曾是占主导地位的催化和遗传聚合物。这一“RNA世界”假说假定，RNA能够进行维持和进化“核生物”所需的所有反应。我的实验室的长期目标之一是选择和进化一种能够在实验室中维持基于RNA的进化的RNA复制酶核酶。这样的系统可以被称为“活的”，它将把化学的基本简单性与生物学的复杂性结合在一起。确定生产RNA复制品所需的最低复杂性将前所未有地让人们了解早期地球在从非生物世界过渡到生物世界时所面临的困难。目标I和II：走向RNA复制酶核酶：我们将使用传统的和基于乳剂的体外选择方法来分离高度进行性的优势RNA聚合酶核酶。目前最先进的聚合酶核酶能够快速形成磷酸二酯键，但几乎不能适当地保持其延伸的引物-模板底物。克服这一核心问题有可能将聚合速率提高十倍或更多，并提供了在以小时为单位的时间尺度内将模板扩展数百个核苷酸的前景-如果实现的话，这是一个令人兴奋的前景！目的II：易位机制与均聚聚合酶：我们将选择将Poly(A)尾巴连续地整合到RNA引物末端的聚合酶核酶。这种聚合酶很有趣，因为长均聚物的过程合成需要一个易位机制，在核苷酸掺入后，必须将聚合酶复合体重新设置为与初始状态完全相同，以便进行迭代聚合。这种机制最终可能被证明是非常有用的，在RNA复制过程中取代非模板链，从而在开发复制酶核酶方面发挥重要作用。