A Local Role for the Small Ribosomal Subunit Primary Binder rpS5 in Final 18S rRNA Processing in Yeast
A Local Role for the Small Ribosomal Subunit Primary Binder rpS5 in Final 18S rRNA Processing in Yeast
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DOI：
10.1371/journal.pone.0010194
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发表时间：
2010-04-19
期刊：
影响因子：
3.7
通讯作者：
Milkereit, Philipp
中科院分区：
文献类型：
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作者：
Neueder, Andreas;Jakob, Steffen;Milkereit, Philipp
酵母小核糖体亚基（SSU）蛋白S5（rpS 5）的体内消耗导致新生SSU的核降解和SSU头部结构域的扰动的全局组装状态。在这里，我们报告说，rpS 5发挥了额外的本地作用，在头部/平台接口，有效的SSU成熟。我们发现，酵母小核糖体亚基，其中纳入了rpS 5变体缺乏7个C-末端氨基酸有一个很大程度上组装的头部结构域，并出口到细胞质。另一方面，18 S rRNA前体的加工在这些核糖体颗粒中被抑制，尽管它们与推定的核酸内切酶Nob 1 p和其他晚期作用的40 S生物发生因子相关。我们认为，SSU头部组件rpS 5和平台组件rpS 14是新生SSU的头部-平台界面中高度定义的空间排列的关键组成部分，这是有效加工其中预测的SSU rRNA 39末端所必需的。rpS 5在新生SSU中的定位，包括其朝向头部-平台裂隙中的平台组分的相对取向，将取决于头部结构域的一般组装和折叠状态。因此，建议的模型可以解释在许多真核SSU头组装突变体中观察到的18 S前体rRNA 39加工表型。
In vivo depletion of the yeast small ribosomal subunit (SSU) protein S5 (rpS5) leads to nuclear degradation of nascent SSUs and to a perturbed global assembly state of the SSU head domain. Here, we report that rpS5 plays an additional local role at the head/platform interface in efficient SSU maturation. We find that yeast small ribosomal subunits which incorporated an rpS5 variant lacking the seven C-terminal amino acids have a largely assembled head domain and are exported to the cytoplasm. On the other hand, 39 processing of 18S rRNA precursors is inhibited in these ribosomal particles, although they associate with the putative endonuclease Nob1p and other late acting 40S biogenesis factors. We suggest that the SSU head component rpS5 and platform components as rpS14 are crucial constituents of a highly defined spatial arrangement in the head - platform interface of nascent SSUs, which is required for efficient processing of the therein predicted SSU rRNA 39 end. Positioning of rpS5 in nascent SSUs, including its relative orientation towards platform components in the head-platform cleft, will depend on the general assembly and folding state of the head domain. Therefore, the suggested model can explain 18S precursor rRNA 39 processing phenotypes observed in many eukaryotic SSU head assembly mutants.