Bud23 promotes the final disassembly of the small subunit Processome in Saccharomyces cerevisiae.
Bud23 promotes the final disassembly of the small subunit Processome in Saccharomyces cerevisiae.
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DOI：
10.1371/journal.pgen.1009215
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发表时间：
2020-12
期刊：
影响因子：
4.5
通讯作者：
Johnson AW
中科院分区：
文献类型：
--
作者：
Black JJ;Sardana R;Elmir EW;Johnson AW
真核细胞核糖体小亚基(SSU)的第一个亚稳态组装中间体是SSU过程组，它是一种由RNA和蛋白质因子组成的大型复合体，被认为是组装途径中的早期检查点。SSU过程组向持续成熟的转变需要去除U3 snoRNA和生物发生因子以及核糖体RNA的加工。虽然推动这些事件的因素在很大程度上是已知的，但它们如何做到这一点却不是很清楚。甲基转移酶Bud23在这一转变中发挥了作用，但它的功能，除了核糖体RNA的非必要甲基化之外，还没有确定。在这里，我们进行了全面的基因筛查，以了解Bud23的功能。我们鉴定了67个独特的基因外BU23Δ抑制突变，这些突变定位于编码SSU过程因子DHR1、IMP4、UTP2(NOP14)、BMS1和SSU蛋白RPS28A的基因。这些因素形成了一个物理相互作用网络，将Bud23的结合位点与U3 snoRNA连接起来，许多氨基酸替换削弱了蛋白质-蛋白质和蛋白质-RNA的相互作用。重要的是，这个网络将Bud23连接到必需的GTP酶Bms1和RNA解旋酶Dhr1上，前者在拆卸过程中作用较晚，后者催化U3 snoRNA的去除。此外，从缺乏Bud23的细胞中分离出的颗粒积累了晚期SSU过程组因子和核糖体RNA加工缺陷。我们提出了一个模型，在该模型中，Bud23解离其结合位点周围的因素以促进SSU进程。核糖体是合成蛋白质的分子机器，由大亚基和小亚基组成，分别执行多肽合成和信使核糖核酸解码的基本功能。核糖体的产生与细胞生长密切相关，因为细胞必须产生足够的核糖体来满足其蛋白质需求。然而，核糖体组装是一种代谢昂贵的途径，必须与其他细胞能量需求平衡，并相应地进行调节。在真核生物中，小亚基(SSU)过程组是一种亚稳定的中间体，最终通过生物发生因子的释放而向成熟的SSU迈进。SSU Processome的进展决定被认为是SSU组装途径的早期检查点，但需要深入了解进展的机制。以前的研究表明，Bud23在SSU过程中扮演着一个未知的角色。在这里，我们使用遗传方法来了解它的功能，并发现Bud23与SSU过程的网络相连，一些因素稳定了粒子。有趣的是，这些因素中有两种是发育所需的酶。我们得出结论，在SSU过程中，Bud23促进其结合位点周围的因子释放，以诱导结构重排。
The first metastable assembly intermediate of the eukaryotic ribosomal small subunit (SSU) is the SSU Processome, a large complex of RNA and protein factors that is thought to represent an early checkpoint in the assembly pathway. Transition of the SSU Processome towards continued maturation requires the removal of the U3 snoRNA and biogenesis factors as well as ribosomal RNA processing. While the factors that drive these events are largely known, how they do so is not. The methyltransferase Bud23 has a role during this transition, but its function, beyond the nonessential methylation of ribosomal RNA, is not characterized. Here, we have carried out a comprehensive genetic screen to understand Bud23 function. We identified 67 unique extragenic bud23Δ-suppressing mutations that mapped to genes encoding the SSU Processome factors DHR1, IMP4, UTP2 (NOP14), BMS1 and the SSU protein RPS28A. These factors form a physical interaction network that links the binding site of Bud23 to the U3 snoRNA and many of the amino acid substitutions weaken protein-protein and protein-RNA interactions. Importantly, this network links Bud23 to the essential GTPase Bms1, which acts late in the disassembly pathway, and the RNA helicase Dhr1, which catalyzes U3 snoRNA removal. Moreover, particles isolated from cells lacking Bud23 accumulated late SSU Processome factors and ribosomal RNA processing defects. We propose a model in which Bud23 dissociates factors surrounding its binding site to promote SSU Processome progression. Ribosomes are the molecular machines that synthesize proteins and are composed of a large and a small subunit which carry out the essential functions of polypeptide synthesis and mRNA decoding, respectively. Ribosome production is tightly linked to cellular growth as cells must produce enough ribosomes to meet their protein needs. However, ribosome assembly is a metabolically expensive pathway that must be balanced with other cellular energy needs and regulated accordingly. In eukaryotes, the small subunit (SSU) Processome is a metastable intermediate that ultimately progresses towards a mature SSU through the release of biogenesis factors. The decision to progress the SSU Processome is thought to be an early checkpoint in the SSU assembly pathway, but insight into the mechanisms of progression is needed. Previous studies suggest that Bud23 plays an uncharacterized role during SSU Processome progression. Here, we used a genetic approach to understand its function and found that Bud23 is connected to a network of SSU Processome factors that stabilize the particle. Interestingly, two of these factors are enzymes that are needed for progression. We conclude that Bud23 promotes the release of factors surrounding its binding site to induce structural rearrangements during the progression of the SSU Processome.
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作者：
Ferreira-Cerca S;Kiburu I;Thomson E;LaRonde N;Hurt E
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Delprato A;Al Kadri Y;Pérébaskine N;Monfoulet C;Henry Y;Henras AK;Fribourg S
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Fribourg S
DOI：
10.1073/pnas.0603673103
发表时间：
2006-06-20
影响因子：
11.1
作者：
Bleichert, Franziska;Grannemant, Sander;Baserga, Susan J.
通讯作者：
Baserga, Susan J.