nifDK Clusters Located on the Chromosome and Megaplasmid of Bradyrhizobium sp. Strain DOA9 Contribute Differently to Nitrogenase Activity During Symbiosis and Free-Living Growth.
nifDK Clusters Located on the Chromosome and Megaplasmid of Bradyrhizobium sp. Strain DOA9 Contribute Differently to Nitrogenase Activity During Symbiosis and Free-Living Growth.
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nifDK 簇位于慢生根瘤菌 (Bradyrhizobium sp.) 的染色体和大质粒上。
DOI：
10.1094/mpmi-07-16-0140-r
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
E. Giraud
中科院分区：
文献类型：
--
作者：
Jenjira Wongdee;Pongpan Songwattana;N. Nouwen;Rujirek Noisangiam;Joël Fardoux;C. Chaintreuil;N. Teaumroong;P. Tittabutr;E. Giraud
慢生根瘤菌菌株DOA9含有两个拷贝的nifDK基因，nifDKc位于染色体上，nifDKp位于共生大质粒上。与大多数根瘤菌不同，这种细菌在自由生活和共生条件下都表现出固氮酶活性。使用gusA报告菌株的转录分析表明，这两个nifDK操纵子的共生下高度表达，而nifDKc是最丰富的自由生活条件下表达。在自由生活的增长，nifDKp突变不影响固氮酶活性，而固氮酶活性急剧下降与nifDKc突变体。这使我们假设nifDKc是自由生活状态下固氮酶活性的主要贡献者。相反，在共生过程中，没有观察到nifDKc突变的影响，并且接种nifDKp突变体的植物的固氮效率降低。这表明nifDKp在共生过程中对固氮酶活性起主要作用。总之，这些数据表明，慢生根瘤菌属菌株DOA9含有两个功能性拷贝的nifDK基因，其受到不同的调节，并且根据其生活方式，对固氮酶活性的贡献不同。
Bradyrhizobium sp. strain DOA9 contains two copies of the nifDK genes, nifDKc, located on the chromosome, and nifDKp, located on a symbiotic megaplasmid. Unlike most rhizobia, this bacterium displays nitrogenase activity under both free-living and symbiotic conditions. Transcriptional analysis using gusA reporter strains showed that both nifDK operons were highly expressed under symbiosis, whereas nifDKc was the most abundantly expressed under free-living conditions. During free-living growth, the nifDKp mutation did not affect nitrogenase activity, whereas nitrogenase activity was drastically reduced with the nifDKc mutant. This led us to suppose that nifDKc is the main contributor of nitrogenase activity in the free-living state. In contrast, during symbiosis, no effect of the nifDKc mutation was observed and the nitrogen-fixation efficiency of plants inoculated with the nifDKp mutant was reduced. This suggests that nifDKp plays the main role in nitrogenase enzyme activity during symbiosis. Together, these data suggest that Bradyrhizobium sp. strain DOA9 contains two functional copies of nifDK genes that are regulated differently and that, depending on their lifestyle, contribute differently to nitrogenase activity.
宿主植物基因组克服了共生固氮细菌基因的缺乏
影响因子：
64.8
作者：
Tsuneo Hakoyama;Kaori Niimi;Hirokazu Watanabe;Ryohei Tabata;Junichi Matsubara;Shusei Sato;Yasukazu Nakamura;Satoshi Tabata;Li Jichun;Tsuyoshi Matsumoto;Kazuyuki Tatsumi;Mika Nomura;Shigeyuki Tajima;Masumi Ishizaka;Koji Yano;Haruko Imaizumi-
通讯作者：
Haruko Imaizumi-