EUKARYOTIC TRNA MATURATION

转移RNA的末端(TRNA)在原核生物和 真核生物是由前体分子裂解而成的 一种结构特异的内切酶，RNaseP，该酶含有 RNA和蛋白质成分，以及仅来自 无论是大肠杆菌还是枯草杆菌都能催化正确的裂解。 此外，这两种原核生物的RNA和蛋白质组分 能互换重组核糖核酸酶P全酶吗 这两个RNA的初级序列几乎没有同源性。 卵裂似乎是通过一种不同于 在RNA剪接反应中观察到的，由辅因子判断 要求和对衬底结构的依赖，而不是 序列。 酵母菌中存在两种形式的核糖核酸酶P。 一种核形式和一种线粒体形式，其仅由 一种RNA成分在线粒体DNA中被编码。我们有 分离出核型，并对RNA组分进行了测序。这 提案详细计划：1)鉴定核糖核酸酶P RNA基因， 3)确定RNaseP全酶的溶液结构， 酶-底物复合体，3)检测酶的哪些特性 和底物RNA结构是正确切割所必需的，4) 探讨其活性部位的结构和作用机制 催化作用和5)决定线粒体和核是否 酶RNA具有相同的蛋白质成分(S)。

Mature 5; termini of transfer RNAs (tRNAs) in both prokaryotes and eukaryotes are generated from precursor molecules by cleavage with a structure-specific endonuclease, RNase P. The enzyme contains both RNA and protein components, and the RNA component alone from either E. coli or B. subtilis can catalyze the correct cleavage. Further, the RNA and protein components from these two prokaryotes can e interchange to reconstitute RNase P holoenzymes even though the primary sequences of the two RNAs show little homology. Cleavage appears to precede through a mechanism distinct from those observed in RNA splicing reactions, as judged by cofactor requirements and the dependence on substrate structure, rather than sequence. Two forms of RNase P have been identified in the yeast S. cerevisiae; a nuclear form and a mitochondrial form from which only an RNA component is encoded in the mitochondrial DNA. We have isolated the nuclear form and sequenced the RNA component. This proposal details plans to: 1) characterize the RNase P RNA gene, 3) determine the solution structure of the RNase P holoenzyme and enzyme-substrate complex, 3) examine which features of the enzymic and substrate RNA structures are required for correct cleavage, 4) investigate the structure of the active site and mechanism of catalysis and 5) determine whether the mitochondrial and nuclear enzymic RNAs share the same protein component(s).