小的自身剪切类核酶（50到150个碱基）发现于30多年前，已发现的每类核酶都具有不同的结构特征和独特的催化中心。最近报道的三类新型小的自身剪切类核酶twister-sister， pistol和hachet中，Pistol核酶是其中最小，但却唯一带假结结构的核酶。那么它是如何折叠形成稳定的核酶结构？该结构又是如何促进酶切反应的进行？哪些核苷酸起着关键作用？有没有Mg2+或其他小分子化合物参与到反应中以及该核酶又具有哪些应用前景？这些问题都尚未得到解决。在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开展对新型核酶pistol的结构与催化机制研究；在此基础上，还将对其生物功能以及潜在的应用前景进行探讨。

Small self-cleaving ribozymes were discovered more than 30 years ago, each ribozyme family has its distinct structure and unique catalytic center. Three new small self-cleaving ribozymes were identified recently including twister-sister, pistol and hachet. Pistol ribozyme is the smallest one, but is also the only one with pseudoknot scaffold structure. So how does the RNA molecules fold into a 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? To answer these questions, we will launch a comprehensive study of the structure and catalytic mechanism of pistol ribozyme using x-ray crystallography method and the related functional study methods.