The Role of Fnr Paralogs in Controlling Anaerobic Metabolism in the Diazotroph Paenibacillus polymyxa WLY78
The Role of Fnr Paralogs in Controlling Anaerobic Metabolism in the Diazotroph Paenibacillus polymyxa WLY78
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Fnr 旁系同源物在控制固氮菌多粘类芽孢杆菌 WLY78 厌氧代谢中的作用
DOI：
10.1128/aem.03012-19
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发表时间：
2020-05-01
影响因子：
4.4
通讯作者：
Chen，Sanfeng
中科院分区：
文献类型：
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作者：
Shi，Haowen;Li，Yongbin;Chen，Sanfeng
固氮类芽孢杆菌属的成员。在农业上作为菌肥具有很大的潜力。然而，fnr基因在类芽孢杆菌固氮和其他代谢中的功能还不清楚。不知道。在这里，我们发现在P.polymyxa WLY78中，Fnr1和Fnr3负责响应氧水平变化的许多基因的调节，但Fnr5和Fnr7表现出很小的影响。Fnr1和Fnr3间接或直接调节许多重要的代谢类型，如固氮、铁吸收、呼吸和电子传递。本研究不仅揭示了多粘类芽孢杆菌WLY78 fnr基因在固氮等代谢中的功能，也为进一步了解fnr基因在类芽孢杆菌中的进化和调控机制提供了理论依据。摘要Fnr是一种转录调节因子，在细菌氧限制反应中控制多种基因的表达。基因组测序揭示了多粘类芽孢杆菌WLY78中编码Fnr蛋白的四个基因（fnr1、fnr3、fnr5和fnr7）。Fnr1和Fnr3之间的相似性高于Fnr5和Fnr7。Fnr1和Fnr3与蜡样芽孢杆菌Fnr和枯草芽孢杆菌Fnr在序列和结构上都有很高的相似性。在大肠杆菌中，经好氧纯化的His标记的Fnr1和His标记的Fnr3均能与特异性DNA启动子结合。缺失分析表明，这4个fnr基因，尤其是fnr1和fnr3，对水稻生长和固氮酶活性有显著影响。单缺失fnr1或fnr3导致固氮酶活性降低50%，而双缺失fnr1和fnr3导致固氮酶活性降低90%。全基因组转录分析表明，Fnr1和Fnr3在厌氧条件下间接激活了固氮基因和铁转运基因的表达。Fnr1和Fnr3抑制参与有氧呼吸链的基因的表达，并激活负责厌氧电子受体基因的基因的表达。重要性固氮类芽孢杆菌属（Paenibacillus spp.）在农业上作为菌肥具有很大的潜力。然而，fnr基因在类芽孢杆菌固氮和其他代谢中的功能还不清楚。不知道。在这里，我们发现在P.polymyxa WLY78中，Fnr1和Fnr3负责响应氧水平变化的许多基因的调节，但Fnr5和Fnr7表现出很小的影响。Fnr1和Fnr3间接或直接调节许多重要的代谢类型，如固氮、铁吸收、呼吸和电子传递。本研究不仅揭示了多粘类芽孢杆菌WLY78 fnr基因在固氮等代谢中的功能，也为进一步了解fnr基因在类芽孢杆菌中的进化和调控机制提供了理论依据。
The members of the nitrogen-fixing Paenibacillus spp. have great potential to be used as a bacterial fertilizer in agriculture. However, the functions of the fnr gene(s) in nitrogen fixation and other metabolisms in Paenibacillus spp. are not known. Here, we found that in P. polymyxa 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 fnr genes of P. polymyxa WLY78 in nitrogen fixation and other metabolisms but also will provide insight into the evolution and regulatory mechanisms of fnr in Paenibacillus. ABSTRACT 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 (fnr1, fnr3, fnr5, and fnr7) coding for Fnr proteins in Paenibacillus polymyxa WLY78. Fnr1 and Fnr3 showed more similarity to each other than to Fnr5 and Fnr7. Also, Fnr1 and Fnr3 exhibited high similarity with Bacillus cereus Fnr and Bacillus subtilis Fnr in sequence and structures. Both the aerobically purified His-tagged Fnr1 and His-tagged Fnr3 in Escherichia coli could bind to the specific DNA promoter. Deletion analysis showed that the four fnr genes, especially fnr1 and fnr3, have significant impacts on growth and nitrogenase activity. Single deletion of fnr1 or fnr3 led to a 50% reduction in nitrogenase activity, and double deletion of fnr1 and fnr3 resulted to a 90% reduction in activity. Genome-wide transcription analysis showed that Fnr1 and Fnr3 indirectly activated expression of nif (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. IMPORTANCE The members of the nitrogen-fixing Paenibacillus spp. have great potential to be used as a bacterial fertilizer in agriculture. However, the functions of the fnr gene(s) in nitrogen fixation and other metabolisms in Paenibacillus spp. are not known. Here, we found that in P. polymyxa 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 fnr genes of P. polymyxa WLY78 in nitrogen fixation and other metabolisms but also will provide insight into the evolution and regulatory mechanisms of fnr in Paenibacillus.