30S ribosomal subunits can be assembled in vivo without primary binding ribosomal protein S15
30S ribosomal subunits can be assembled in vivo without primary binding ribosomal protein S15
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DOI：
10.1261/rna.2262106
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发表时间：
2006-07-01
期刊：
影响因子：
4.5
通讯作者：
Culver, Gloria M.
中科院分区：
文献类型：
--
作者：
Bubunenko, Mikhail;Korepanov, Alexey;Culver, Gloria M.
使用体外系统详细解剖了大肠杆菌 30S 核糖体亚基的组装。这些研究已经能够表征核糖体蛋白 S15 在 30S 亚基的分层组装中的作用； S15 是一种主要结合蛋白，协调核糖体蛋白 S6、S11、S18 和 S21 与 16S 核糖体 RNA 的中心结构域的组装，形成 30S 亚基的平台。体外 S15 是该级联中唯一的主要结合蛋白，在这四种蛋白的组装过程中发挥着关键作用。为了研究 S15 在体内的作用，对编码 S15 的基因 rpsO 的基本性质进行了检查。令人惊讶的是，具有读码框内删除 rpsO 的大肠杆菌仍能存活，尽管在 37 摄氏度下，该 Delta rpsO 菌株与其亲本菌株相比，其倍增时间过长。在没有S15的情况下，其余四种平台蛋白在体内组装成核糖体，并且在37℃下DrpsO菌株中形成的30S亚基的整体结构没有改变。尽管如此，缺乏S15的30S亚基在体内和体外的亚基关联方面似乎有些缺陷。此外，该菌株对冷敏感，在低温下表现出明显的核糖体生物发生缺陷，表明在非理想条件下S15对于组装至关重要。该菌株的活力表明 70S 核糖体的体内功能群必须在没有 S15 的情况下形成，并且 30S 亚基组装具有先前未揭示或表征的可塑性。
Assembly of 30S ribosomal subunits from Escherichia coli has been dissected in detail using an in vitro system. Such studies have allowed characterization of the role for ribosomal protein S15 in the hierarchical assembly of 30S subunits; S15 is a primary binding protein that orchestrates the assembly of ribosomal proteins S6, S11, S18, and S21 with the central domain of 16S ribosomal RNA to form the platform of the 30S subunit. In vitro S15 is the sole primary binding protein in this cascade, performing a critical role during assembly of these four proteins. To investigate the role of S15 in vivo, the essential nature of rpsO, the gene encoding S15, was examined. Surprisingly, E. coli with an in-frame deletion of rpsO are viable, although at 37 degrees C this Delta rpsO strain has an exaggerated doubling time compared to its parental strain. In the absence of S15, the remaining four platform proteins are assembled into ribosomes in vivo, and the overall architecture of the 30S subunits formed in the DrpsO strain at 37 degrees C is not altered. Nonetheless, 30S subunits lacking S15 appear to be somewhat defective in subunit association in vivo and in vitro. In addition, this strain is cold sensitive, displaying a marked ribosome biogenesis defect at low temperature, suggesting that under nonideal conditions S15 is critical for assembly. The viability of this strain indicates that in vivo functional populations of 70S ribosomes must form in the absence of S15 and that 30S subunit assembly has a plasicity that has not previously been revealed or characterized.