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。

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.