Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA.
Curr Genet. 2021 Oct;67(5):729-738. doi: 10.1007/s00294-021-01187-y. Epub 2021 Apr 12.
The assembly of eukaryotic ribosomes follows an assembly line-like pathway in which numerous trans-acting biogenesis factors act on discrete pre-ribosomal intermediates to progressively shape the nascent subunits into their final functional architecture. Recent advances in cryo-electron microscopy have led to high-resolution structures of many pre-ribosomal intermediates; however, these static snapshots do not capture the dynamic transitions between these intermediates. To this end, molecular genetics can be leveraged to reveal how the biogenesis factors drive these dynamic transitions. Here, we briefly review how we recently used the deletion of BUD23 (bud23∆) to understand its role in the assembly of the ribosomal small subunit. The strong growth defect of bud23∆ mutants places a selective pressure on yeast cells for the occurrence of extragenic suppressors that define a network of functional interactions among biogenesis factors. Mapping these suppressing mutations to recently published structures of pre-ribosomal complexes allowed us to contextualize these suppressing mutations and derive a detailed model in which Bud23 promotes a critical transition event to facilitate folding of the central pseudoknot of the small subunit. This mini-review highlights how genetics can be used to understand the dynamics of complex structures, such as the maturing ribosome.
真核核糖体的组装遵循流水线样的途径，在此过程中，许多反式作用的生物发生因子作用于离散的前核糖体中间产物，逐渐将新生亚基塑造成其最终的功能结构。最近的低温电子显微镜技术的进展导致了许多前核糖体中间产物的高分辨率结构；然而，这些静态快照并没有捕获这些中间产物之间的动态转变。为此，可以利用分子遗传学来揭示生物发生因子如何驱动这些动态转变。在这里，我们简要回顾了我们最近如何利用 BUD23（bud23∆）的缺失来了解其在核糖体小亚基组装中的作用。bud23∆突变体的强烈生长缺陷对酵母细胞施加了选择性压力，使其发生外显子抑制突变，从而定义了生物发生因子之间的功能相互作用网络。将这些抑制突变映射到最近发表的前核糖体复合物结构上，使我们能够将这些抑制突变置于上下文中，并得出一个详细的模型，其中 Bud23 促进了一个关键的转变事件，以促进小亚基中心假结的折叠。这篇迷你综述强调了遗传学如何用于理解复杂结构（如成熟核糖体）的动力学。
