Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Genes (Basel). 2024 Feb 15;15(2):247. doi: 10.3390/genes15020247.
RNA polymerase I (Pol I) is responsible for synthesizing the three largest eukaryotic ribosomal RNAs (rRNAs), which form the backbone of the ribosome. Transcription by Pol I is required for cell growth and, therefore, is subject to complex and intricate regulatory mechanisms. To accomplish this robust regulation, the cell engages a series of trans-acting transcription factors. One such factor, high mobility group protein 1 (Hmo1), has long been established as a trans-acting factor for Pol I in ; however, the mechanism by which Hmo1 promotes rRNA synthesis has not been defined. Here, we investigated the effect of the deletion of on transcription elongation by Pol I in vivo. We determined that Hmo1 is an important activator of transcription elongation, and without this protein, Pol I accumulates across rDNA in a sequence-specific manner. Our results demonstrate that Hmo1 promotes efficient transcription elongation by rendering Pol I less sensitive to pausing in the G-rich regions of rDNA.
RNA 聚合酶 I（Pol I）负责合成三个最大的真核核糖体 RNA（rRNA），它们构成核糖体的骨架。Pol I 的转录是细胞生长所必需的，因此受到复杂而精细的调节机制的调控。为了实现这种强大的调控，细胞利用一系列反式作用转录因子。高迁移率族蛋白 1（Hmo1）就是这样一种反式作用因子，它长期以来一直被认为是 Pol I 的反式作用因子；然而，Hmo1 促进 rRNA 合成的机制尚未确定。在这里，我们研究了缺失对 Pol I 在体内转录延伸的影响。我们确定 Hmo1 是转录延伸的重要激活剂，没有这种蛋白质，Pol I 就会以序列特异性的方式在 rDNA 上积累。我们的结果表明，Hmo1 通过使 Pol I 对 rDNA 中富含 G 的区域的暂停不那么敏感，从而促进有效的转录延伸。
