tRNase Z reaction is central to tRNA maturation

描述（由申请人提供）： 转运RNA（tRNA）是蛋白质合成的核心。像其他RNA一样，tRNA作为前体转录，必须经历成熟。RNase P去除5'前导序列。核酸内切酶tRNase Z去除3'尾部，使得CCA可以通过tRNA核苷酸转移酶添加。因此，tRNase Z反应是前tRNA成熟的关键步骤。从远离活性位点的tRNase Z体中挤出一个柔性臂（FA）。球状FA手主要与tRNA手肘（D/T环）结合，远离易断裂的键。人类线粒体tRNA的天然突变与母系传播的疾病和综合征有关，主要是肌病。[Aim 1]病程相关的线粒体tRNA突变的分布是否与tRNA结构变化和对tRNase Z加工的影响相关？将研究发病机制相关的T环置换的影响。[Aim 2]蛋白酶敏感性是否报告tRNase Z FA的灵活性？质谱分析将揭示一种新的底物识别机制。[Aim 3]前tRNA 3'末端可能在tRNase Z反应后进入调控网络吗？我们将研究在假设途径的早期步骤中，tRNase Z切割的前tRNA 3'尾部产物与La和Ago家族成员的结合。

DESCRIPTION (provided by applicant): Transfer RNA (tRNA) is central to protein synthesis. Like other RNAs, tRNA is transcribed as a precursor and must undergo maturation. RNase P removes the 5' leader. The endonuclease tRNase Z removes the 3' trailer so that CCA can be added by tRNA nucleotidyltransferase. tRNase Z reaction is thus a critical step in pre- tRNA maturation. A flexible arm (FA) is extruded from the body of tRNase Z remote from the active site. The globular FA hand principally binds to the elbow (D/T loops) of tRNA, far from the scissile bond. Naturally occurring mutations in human mitochondrial tRNAs are associated with maternally transmitted diseases and syndromes, principally myopathies. [Aim 1] Does the distribution of pathogenesis-related mitochondrial tRNA mutations correlate with tRNA structure changes and effects on tRNase Z processing? Effects of pathogenesis-related T loop substitutions will be investigated. [Aim 2] Does protease susceptibility report on flexibility of the tRNase Z FA? The mass spectroscopic analysis will shed light on a novel mechanism of substrate recognition. [Aim 3] Might pre-tRNA 3' trailers enter a regulatory network following tRNase Z reaction? We will investigate binding of the pre-tRNA 3' trailer products of tRNase Z cleavage to La and members of the Ago family in early steps of the hypothesized pathway.