Department of Microbiology, The Ohio State University, Columbus, OH 43210.
Center for RNA Biology, The Ohio State University, Columbus, OH 43210.
Proc Natl Acad Sci U S A. 2017 Jan 31;114(5):980-985. doi: 10.1073/pnas.1613665114. Epub 2017 Jan 17.
The physiological role of LepA, a paralog of EF-G found in all bacteria, has been a mystery for decades. Here, we show that LepA functions in ribosome biogenesis. In cells lacking LepA, immature 30S particles accumulate. Four proteins are specifically underrepresented in these particles-S3, S10, S14, and S21-all of which bind late in the assembly process and contribute to the folding of the 3' domain of 16S rRNA. Processing of 16S rRNA is also delayed in the mutant strain, as indicated by increased levels of precursor 17S rRNA in assembly intermediates. Mutation ΔlepA confers a synthetic growth phenotype in absence of RsgA, another GTPase, well known to act in 30S subunit assembly. Analysis of the ΔrsgA strain reveals accumulation of intermediates that resemble those seen in the absence of LepA. These data suggest that RsgA and LepA play partially redundant roles to ensure efficient 30S assembly.
LepA 是一种在所有细菌中都存在的 EF-G 平行物，其生理作用几十年来一直是个谜。在这里，我们表明 LepA 在核糖体生物发生中起作用。在缺乏 LepA 的细胞中，不成熟的 30S 颗粒积累。在这些颗粒中，有四种蛋白质特别缺乏-S3、S10、S14 和 S21-所有这些蛋白质都在组装过程的后期结合，并有助于 16S rRNA 的 3' 结构域折叠。突变菌株中的 16S rRNA 加工也被延迟，这表现为组装中间体中前体 17S rRNA 的水平增加。突变 ΔlepA 在没有另一种 GTP 酶 RsgA 的情况下赋予了合成生长表型，RsgA 众所周知可在 30S 亚基组装中发挥作用。对 ΔrsgA 菌株的分析表明，中间产物的积累类似于在缺乏 LepA 的情况下观察到的情况。这些数据表明，RsgA 和 LepA 发挥部分冗余作用，以确保 30S 组装的高效性。
