PNPase activity determines the efficiency of mRNA 3′‐end processing, the degradation of tRNA and the extent of polyadenylation in chloroplasts
PNPase activity determines the efficiency of mRNA 3′‐end processing, the degradation of tRNA and the extent of polyadenylation in chloroplasts
复制标题
DOI：
10.1093/emboj/cdf686
复制
发表时间：
2002-12
期刊：
影响因子：
--
通讯作者：
Michael Walter;Joachim Kilian;J. Kudla
中科院分区：
文献类型：
--
作者：
Michael Walter;Joachim Kilian;J. Kudla
核糖核酸外切酶多核苷酸磷酸化酶（PNDase）参与细菌以及高等植物叶绿体中的mRNA加工和降解。在这里，我们报告的第一个全面的叶绿体PNIPs功能的体内研究。通过反向遗传方法调节拟南芥叶绿体中的PNTR活性表明，尽管这种酶对于有效的mRNA 3′-末端加工是必需的，但它不足以介导转录物降解。令人惊讶的是，我们发现PNTR也是23 S rRNA转录物3′端成熟不可或缺的。在转基因拟南芥植物中的tRNA量的分析表明，PNTR活性和tRNA水平的直接相关性，表明这种外切核酸酶在tRNA衰变中的额外功能。此外，叶绿体中多聚腺苷酸化的mRNA的程度与PNIPs活性呈负相关。总之，我们的研究结果归因于新的功能，PNTR在所有主要类别的质体RNA的代谢，并建议一个意想不到的复杂的作用PNTR在RNA加工和衰变。
The exoribonuclease polynucleotide phosphorylase (PNPase) has been implicated in mRNA processing and degradation in bacteria as well as in chloroplasts of higher plants. Here, we report the first comprehensive in vivo study of chloroplast PNPase function. Modulation of PNPase activity in Arabidopsis chloroplasts by a reverse genetic approach revealed that, although this enzyme is essential for efficient 3′‐end processing of mRNAs, it is insufficient to mediate transcript degradation. Surprisingly, we identified PNPase as also being indispensable for 3′‐end maturation of 23S rRNA transcripts. Analysis of tRNA amounts in transgenic Arabidopsis plants suggests a direct correlation of PNPase activity and tRNA levels, indicating an additional function of this exoribo nuclease in tRNA decay. Moreover, the extent of polyadenylated mRNAs in chloroplasts is negatively correlated with PNPase activity. Together, our results attribute novel functions to PNPase in the metabolism of all major classes of plastid RNAs and suggest an unexpectedly complex role for PNPase in RNA processing and decay.