State Key Laboratory for Agrobiotechnology, College of Biological Sciences and Key Laboratory of Soil Microbiology of Agriculture Ministry, China Agricultural University, Beijing, People's Republic of China.
State Key Laboratory for Agrobiotechnology, College of Biological Sciences and Key Laboratory of Soil Microbiology of Agriculture Ministry, China Agricultural University, Beijing, People's Republic of China
Appl Environ Microbiol. 2020 May 5;86(10). doi: 10.1128/AEM.03012-19.
Fnr is a transcriptional regulator that controls the expression of a variety of genes in response to oxygen limitation in bacteria. Genome sequencing revealed four genes (, , , and ) coding for Fnr proteins in WLY78. Fnr1 and Fnr3 showed more similarity to each other than to Fnr5 and Fnr7. Also, Fnr1 and Fnr3 exhibited high similarity with Fnr and Fnr in sequence and structures. Both the aerobically purified His-tagged Fnr1 and His-tagged Fnr3 in could bind to the specific DNA promoter. Deletion analysis showed that the four genes, especially and , have significant impacts on growth and nitrogenase activity. Single deletion of or led to a 50% reduction in nitrogenase activity, and double deletion of and resulted to a 90% reduction in activity. Genome-wide transcription analysis showed that Fnr1 and Fnr3 indirectly activated expression of (nitrogen fixation) genes and Fe transport genes under anaerobic conditions. Fnr1 and Fnr3 inhibited expression of the genes involved in the aerobic respiratory chain and activated expression of genes responsible for anaerobic electron acceptor genes. The members of the nitrogen-fixing spp. have great potential to be used as a bacterial fertilizer in agriculture. However, the functions of the gene(s) in nitrogen fixation and other metabolisms in spp. are not known. Here, we found that in WLY78, Fnr1 and Fnr3 were responsible for regulation of numerous genes in response to changes in oxygen levels, but Fnr5 and Fnr7 exhibited little effect. Fnr1 and Fnr3 indirectly or directly regulated many types of important metabolism, such as nitrogen fixation, Fe uptake, respiration, and electron transport. This study not only reveals the function of the genes of WLY78 in nitrogen fixation and other metabolisms but also will provide insight into the evolution and regulatory mechanisms of in .
Fnr 是一种转录调节因子，可控制细菌在氧限制下各种基因的表达。基因组测序显示，WLY78 中有四个基因（，，，和）编码 Fnr 蛋白。Fnr1 和 Fnr3 彼此之间的相似性比 Fnr5 和 Fnr7 更高。此外，Fnr1 和 Fnr3 在序列和结构上与 Fnr 和 Fnr 表现出高度相似性。在好氧条件下纯化的带有 His 标签的 Fnr1 和 Fnr3 均可与特定的 DNA 启动子结合。缺失分析表明，四个 基因，特别是 和 ，对生长和固氮酶活性有显著影响。缺失 或 会导致固氮酶活性降低 50%，而缺失 和 则会导致活性降低 90%。全基因组转录分析表明，Fnr1 和 Fnr3 可在厌氧条件下间接激活 （固氮）基因和 Fe 转运基因的表达。Fnr1 和 Fnr3 抑制参与需氧呼吸链的基因表达，并激活负责厌氧电子受体基因的基因表达。固氮 spp.的成员具有巨大的潜力可作为农业中的细菌肥料。然而，在 spp.中， 基因在固氮和其他代谢中的功能尚不清楚。在这里，我们发现，在 WLY78 中，Fnr1 和 Fnr3 负责调节许多基因以响应氧水平的变化，但 Fnr5 和 Fnr7 几乎没有影响。Fnr1 和 Fnr3 间接或直接调节许多重要代谢类型，如固氮、Fe 摄取、呼吸和电子传递。这项研究不仅揭示了 WLY78 中 基因在固氮和其他代谢中的功能，而且还将深入了解 在进化和调控机制方面的情况。
