Department of Biophysics, UT Southwestern Medical Center - ND10.124B, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA.
O'Donnell Brain Institute/CAND, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA.
Nat Commun. 2024 Apr 17;15(1):3296. doi: 10.1038/s41467-024-47616-7.
DEAD-box ATPases play crucial roles in guiding rRNA restructuring events during the biogenesis of large (60S) ribosomal subunits, but their precise molecular functions are currently unknown. In this study, we present cryo-EM reconstructions of nucleolar pre-60S intermediates that reveal an unexpected, alternate secondary structure within the nascent peptidyl-transferase-center (PTC). Our analysis of three sequential nucleolar pre-60S intermediates reveals that the DEAD-box ATPase Dbp10/DDX54 remodels this alternate base pairing and enables the formation of the rRNA junction that anchors the mature form of the universally conserved PTC A-loop. Post-catalysis, Dbp10 captures rRNA helix H61, initiating the concerted exchange of biogenesis factors during late nucleolar 60S maturation. Our findings show that Dbp10 activity is essential for the formation of the ribosome active site and reveal how this function is integrated with subsequent assembly steps to drive the biogenesis of the large ribosomal subunit.
DEAD-box ATPases 在引导大（60S）核糖体亚基生物发生过程中的 rRNA 重排事件中发挥着关键作用，但它们的确切分子功能目前尚不清楚。在这项研究中，我们提供了核仁前 60S 中间体的冷冻电镜重建，揭示了新生肽基转移酶中心（PTC）内出乎意料的替代二级结构。我们对三个连续的核仁前 60S 中间体的分析表明，DEAD-box ATPase Dbp10/DDX54 重塑了这种替代碱基配对，并能够形成锚定普遍保守的 PTC A 环成熟形式的 rRNA 连接。在催化后，Dbp10 捕获 rRNA 螺旋 H61，启动核仁晚期 60S 成熟过程中生物发生因子的协同交换。我们的发现表明 Dbp10 活性对于核糖体活性位点的形成是必不可少的，并揭示了这一功能如何与随后的组装步骤相结合，以推动大核糖体亚基的生物发生。
