Cameron Jeffrey C, Gordon Gina C, Pfleger Brian F
Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 3629 Engineering Hall, 1415 Engineering Dr., Madison, WI, 53706, USA.
Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, USA.
Photosynth Res. 2015 Oct;126(1):171-83. doi: 10.1007/s11120-015-0076-2. Epub 2015 Jan 17.
Cyanobacteria are diverse photosynthetic microbes with the ability to convert CO2 into useful products. However, metabolic engineering of cyanobacteria remains challenging because of the limited resources for modifying the expression of endogenous and exogenous biochemical pathways. Fine-tuned control of protein production will be critical to optimize the biological conversion of CO2 into desirable molecules. Messenger RNAs (mRNAs) are labile intermediates that play critical roles in determining the translation rate and steady-state protein concentrations in the cell. The majority of studies on mRNA turnover have focused on the model heterotrophic bacteria Escherichia coli and Bacillus subtilis. These studies have elucidated many RNA modifying and processing enzymes and have highlighted the differences between these Gram-negative and Gram-positive bacteria, respectively. In contrast, much less is known about mRNA turnover in cyanobacteria. We generated a compendium of the major ribonucleases (RNases) and provide an in-depth analysis of RNase III-like enzymes in commonly studied and diverse cyanobacteria. Furthermore, using targeted gene deletion, we genetically dissected the RNases in Synechococcus sp. PCC 7002, one of the fastest growing and industrially attractive cyanobacterial strains. We found that all three cyanobacterial homologs of RNase III and a member of the RNase II/R family are not essential under standard laboratory conditions, while homologs of RNase E/G, RNase J1/J2, PNPase, and a different member of the RNase II/R family appear to be essential for growth. This work will enhance our understanding of native control of gene expression and will facilitate the development of an RNA-based toolkit for metabolic engineering in cyanobacteria.
蓝细菌是多种多样的光合微生物，能够将二氧化碳转化为有用的产物。然而，由于用于修饰内源性和外源性生化途径表达的资源有限，蓝细菌的代谢工程仍然具有挑战性。对蛋白质生产进行精细调控对于优化二氧化碳向所需分子的生物转化至关重要。信使核糖核酸（mRNA）是不稳定的中间体，在决定细胞中的翻译速率和稳态蛋白质浓度方面发挥着关键作用。大多数关于mRNA周转的研究都集中在模式异养细菌大肠杆菌和枯草芽孢杆菌上。这些研究阐明了许多RNA修饰和加工酶，并分别突出了这些革兰氏阴性菌和革兰氏阳性菌之间的差异。相比之下，人们对蓝细菌中mRNA周转的了解要少得多。我们生成了主要核糖核酸酶（RNase）的汇编，并对常见且多样的蓝细菌中的RNase III样酶进行了深入分析。此外，通过靶向基因缺失，我们对聚球藻属PCC 7002（生长最快且在工业上具有吸引力的蓝细菌菌株之一）中的核糖核酸酶进行了基因剖析。我们发现，在标准实验室条件下，RNase III的所有三种蓝细菌同源物以及RNase II/R家族的一个成员并非必需，而RNase E/G、RNase J1/J2、PNPase的同源物以及RNase II/R家族的另一个成员似乎对生长至关重要。这项工作将增进我们对基因表达天然调控的理解，并将促进用于蓝细菌代谢工程的基于RNA的工具包的开发。
