Department of Microbiology and Molecular Genetics, Institute of Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 9112010, Israel.
The Kuvin Center for the Study of Infectious and Tropical Diseases, Institute of Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 9112010, Israel.
Proc Natl Acad Sci U S A. 2023 Oct 17;120(42):e2307185120. doi: 10.1073/pnas.2307185120. Epub 2023 Oct 13.
Precursor tRNAs are transcribed with flanking and intervening sequences known to be processed by specific ribonucleases. Here, we show that transcription complexes of RNA polymerase III assembled on tRNA genes comprise RNase P that cleaves precursor tRNA and subsequently degrades the excised 5' leader. Degradation is based on a 3'-5' exoribonucleolytic activity carried out by the protein subunit Rpp14, as determined by biochemical and reverse genetic analyses. Neither reconstituted nor purified RNase P displays this magnesium ion-dependent, processive exoribonucleolytic activity. Markedly, knockdown of Rpp14 by RNA interference leads to a wide-ranging inhibition of cleavage of flanking and intervening sequences of various precursor tRNAs in extracts and cells. This study reveals that RNase P controls tRNA splicing complex and RNase Z for ordered maturation of nascent precursor tRNAs by transcription complexes.
前体 tRNA 是通过侧翼和间隔序列转录的，这些序列已知是由特定的核糖核酸酶加工的。在这里，我们表明，RNA 聚合酶 III 组装在 tRNA 基因上的转录复合物包含能够切割前体 tRNA 的 RNase P，随后降解切除的 5' 前导序列。降解基于由蛋白亚基 Rpp14 执行的 3'-5' 外切核糖核酸酶活性，这是通过生化和反向遗传分析确定的。无论是重组的还是纯化的 RNase P 都不具有这种依赖于镁离子的、连续的外切核糖核酸酶活性。值得注意的是，通过 RNA 干扰敲低 Rpp14 会导致各种前体 tRNA 的侧翼和间隔序列在提取物和细胞中的切割广泛抑制。这项研究揭示了 RNase P 通过转录复合物控制 tRNA 剪接复合物和 RNase Z，以实现新生前体 tRNA 的有序成熟。
