Pneumococcal RNase R globally impacts protein synthesis by regulating the amount of actively translating ribosomes
Pneumococcal RNase R globally impacts protein synthesis by regulating the amount of actively translating ribosomes
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DOI：
10.1080/15476286.2018.1564616
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发表时间：
2019-02-01
期刊：
影响因子：
4.1
通讯作者：
Arraiano, Cecilia Maria
中科院分区：
文献类型：
--
作者：
Barria, Catia;Domingues, Susana;Arraiano, Cecilia Maria
核糖体是进行蛋白质合成的大分子机器。在每一轮翻译之后，核糖体循环对于重新启动蛋白质合成至关重要。核糖体再循环因子（RRF）与延伸因子G （EF-G）共同催化70S核糖体瞬间分裂为亚基。这种分裂随后被起始因子3 （IF3）稳定，IF3起着抗关联因子的作用。这些因子的正确数量保证了细胞中70S核糖体的精确水平。RNase R是一种高度保守的外核糖核酸酶，参与rna的3MODIFIER LETTER PRIME到5MODIFIER LETTER PRIME降解。在这项工作中，我们发现肺炎球菌RNase R直接控制frr、fusA和infC mrna的表达水平，分别是RRF、EF-G和IF3的相应转录本。我们提供的证据表明，这些因素的积累导致70S活性颗粒的数量减少，正如RNase R突变株中蔗糖梯度核糖体模式的改变所证明的那样。此外，RNase R的单个缺失被证明对蛋白质合成和细胞活力具有全局影响，导致细菌CFU/ml减少50%。我们认为，RNase R对这些转录本的微调调节对于维持正确mRNA翻译所需的活性核糖体复合物的精确数量至关重要，因此我们提出RNase R作为核糖体重新结合的新辅助因子。考虑到RNase R对蛋白质合成（抗生素的主要靶点之一）的整体影响，该酶可能是抗菌治疗的一个有希望的靶点。
Ribosomes are macromolecular machines that carry out protein synthesis. After each round of translation, ribosome recycling is essential for reinitiating protein synthesis. Ribosome recycling factor (RRF), together with elongation factor G (EF-G), catalyse the transient split of the 70S ribosome into subunits. This splitting is then stabilized by initiation factor 3 (IF3), which functions as an anti-association factor. The correct amount of these factors ensures the precise level of 70S ribosomes in the cell. RNase R is a highly conserved exoribonuclease involved in the 3MODIFIER LETTER PRIME to 5MODIFIER LETTER PRIME degradation of RNAs. In this work we show that pneumococcal RNase R directly controls the expression levels of frr, fusA and infC mRNAs, the corresponding transcripts of RRF, EF-G and IF3, respectively. We present evidences showing that accumulation of these factors leads to a decreased amount of 70S active particles, as demonstrated by the altered sucrose gradient ribosomal pattern in the RNase R mutant strain. Furthermore, the single deletion of RNase R is shown to have a global impact on protein synthesis and cell viability, leading to a similar to 50% reduction in bacterial CFU/ml. We believe that the fine-tuned regulation of these transcripts by RNase R is essential for maintaining the precise amount of active ribosomal complexes required for proper mRNA translation and thus we propose RNase R as a new auxiliary factor in ribosome reassociation. Considering the overall impact of RNase R on protein synthesis, one of the main targets of antibiotics, this enzyme may be a promising target for antimicrobial treatment.