具有催化功能的非编码RNA的结构与作用机制研究

Ribozymes are non-coding RNA molecules, which can specifically catalyze the chemical or bio-chemical reactions. Studies of the structural and catalytic mechanism of these ribozymes will help to discover new non-coding RNA molecules and new function of non-coding RNA molecules. Small self-cleaving ribozymes were discovered more than 30 years ago, only nine families were discovered until now. Each family has its distinct structure and unique catalytic center. Three new small genome self-cleaving ribozymes including twister-sister, pistol and hachet were identified recently at the same time and reported as a hotspot in ribozyme field. But the research on the catalytic mechanism was hindered by the lack of their structural information. So how does the RNA molecules containing only 4 nucleotides fold into the stable three-dimension structure? How does the structure catalyze the cleavage reaction? Which nucleotides play the key roles in cleavage reaction? Is there any Mg2+ or small molecule involved in the reaction? And what’s the potential application of the new ribozymes? What’s the relationship of these ribozymes in the origin and evolution of biological world? What are their important biological functions and the potential application? To answer these questions, we will launch a comprehensive study of the structure and catalytic mechanism of these ribozymes using x-ray crystallography method and the related functional study methods.

核酶是一类重要的具有催化功能的非编码RNA分子。对核酶的研究有助于发现新的非编码RNA分子、探索非编码RNA分子新的功能。小的自身剪切类核酶（50到150个碱基）发现于30多年前，至今仅发现九类，每类核酶均具有不同的结构和独特的催化中心。其中最近同时被热点报道的三类新型核酶twister-sister，pistol和hachet由于缺少全面的三维结构信息而无法作进一步的研究和探讨。仅含有四类核苷酸碱基的RNA分子是如何折叠形成不同的三维结构？如何促进酶切反应的进行？哪些核苷酸碱基起着关键作用？有没有Mg2+或其他小分子参与到反应中？ 这些核酶具有什么样的生物功能，又具有哪些应用前景？它们在生命的起源和进化中有什么作用？本项目中申请人将通过x-射线晶体学的方法以及相关的功能实验研究几类新型核酶的结构与催化机制；在此基础上，还将对其生物功能、潜在的应用前景以及它们在起源和进化上的作用进行探讨。

核酶是具有催化功能的非编码RNA分子，参与很多重要的细胞活动。小的自剪切型核酶（small self-cleaving ribozyme）发现于30多年前，长度在50到150 个碱基之间，至今只有九种该类核酶被报道。在国家自然科学基金委员会重大研究计划培育项目《具有催化功能的非编码RNA的结构与作用机制研究》的资助下，申请人课题组对2015年耶鲁大学的Breaker教授课题组报道的三类新型自剪切型核酶——Pistol， Twister-sister和 hatchet核酶分别进行了结构与作用机制研究。利用X-射线晶体学的方法，申请人课题组分别解析了Pistol核酶催化前体，Twister-sister核酶催化前体以及Hatchet核酶催化产物的三维结构；结合相关的分子生物学、酶学等实验；探讨了它们的催化过程，鉴定了影响催化过程的关键碱基，并对它们的催化机制进行了深入的探讨。我们的研究为开发核酶在生物学、医学、药学等方面的潜在应用提供了重要的理论基础；也为“RNA世界学说”提供更有力的证据和支持。

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