Cavaiuolo Marina, Chagneau Carine, Laalami Soumaya, Putzer Harald
UMR 8261, CNRS, Institut de Biologie Physico-Chimique, Université de Paris, Paris, France.
Front Microbiol. 2020 Jun 3;11:1055. doi: 10.3389/fmicb.2020.01055. eCollection 2020.
mRNA levels result from an equilibrium between transcription and degradation. Ribonucleases (RNases) facilitate the turnover of mRNA, which is an important way of controlling gene expression, allowing the cells to adjust transcript levels to a changing environment. In contrast to the heterotrophic model bacteria and , RNA decay has not been studied in detail in cyanobacteria. sp. PCC6803 encodes orthologs of both and RNases, including RNase E and RNase J, respectively. We show that RNases E and J have an endonucleolytic cleavage specificity that is very similar between them and also compared to orthologous enzymes from , and Moreover, RNase J displays a robust 5'-exoribonuclease activity similar to RNase J1, but unlike the evolutionarily related RNase J in chloroplasts. Both nucleases are essential and gene deletions could not be fully segregated in . We generated partially disrupted strains of RNase E and J that were stable enough to allow for their growth and characterization. A transcriptome analysis of these strains partially depleted for RNases E and J, respectively, allowed to observe effects on specific transcripts. RNase E altered the expression of a larger number of chromosomal genes and antisense RNAs compared to RNase J, which rather affects endogenous plasmid encoded transcripts. Our results provide the first description of the main transcriptomic changes induced by the partial depletion of two essential ribonucleases in cyanobacteria.
mRNA水平是转录和降解之间平衡的结果。核糖核酸酶（RNases）促进mRNA的周转，这是控制基因表达的重要方式，使细胞能够根据不断变化的环境调整转录水平。与异养模式细菌不同，蓝藻中RNA衰变尚未得到详细研究。集胞藻属PCC6803分别编码RNase E和RNase J这两种RNases的直系同源物。我们发现，集胞藻属的RNase E和J具有内切核酸酶切割特异性，它们之间以及与大肠杆菌、枯草芽孢杆菌和嗜热栖热菌的直系同源酶相比都非常相似。此外，集胞藻属RNase J表现出强大的5'-外切核糖核酸酶活性，类似于枯草芽孢杆菌RNase J1，但与叶绿体中进化相关的RNase J不同。这两种核酸酶都是必需的，基因缺失在集胞藻属中无法完全分离。我们构建了集胞藻属RNase E和J的部分缺失菌株，这些菌株足够稳定，能够进行生长和特性鉴定。对这些分别部分缺失RNase E和J的菌株进行转录组分析，从而观察对特定转录本的影响。与RNase J相比，RNase E改变了更多染色体基因和反义RNA的表达，而RNase J则主要影响内源质粒编码的转录本。我们的结果首次描述了蓝藻中两种必需核糖核酸酶部分缺失所引起的主要转录组变化。
