To downregulate gene expression in cyanobacteria, we constructed NOT gate genetic circuits using orthogonal promoters and their cognate repressors regulated translationally by synthetic riboswitches. Four NOT gates were tested and characterized in five cyanobacterial strains using fluorescent reporter-gene assays. In comparison to alternative systems used to downregulate gene expression in cyanobacteria, these NOT gates performed well, reducing YFP reporter expression by 4 to 50-fold. We further evaluated these NOT gates by controlling the expression of the ftsZ gene, which encodes a prokaryotic tubulin homologue that is required for cell division and is essential for Synechococcus elongatus PCC 7942. These NOT gates would facilitate cyanobacterial genetic engineering or the study of essential cellular processes.

中文翻译：

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非门遗传电路来控制蓝细菌中的基因表达

为了下调蓝藻中的基因表达，我们使用正交启动子及其通过合成核糖开关翻译调控的同源阻遏物构建了非门遗传电路。使用荧光报告基因检测法测试了四个非门，并在五个蓝细菌菌株中进行了表征。与用于下调蓝细菌基因表达的替代系统相比，这些NOT门的效果很好，将YFP报告基因的表达降低了4到50倍。我们通过控制ftsZ基因的表达进一步评估了这些非门，该基因编码细胞分裂所必需的原核微管蛋白同源物，并且对于延伸突触球菌是必不可少的 PCC7942。这些非门将促进蓝细菌基因工程或基本细胞过程的研究。