The nitrate-sensing NasST system regulates nitrous oxide reductase and periplasmic nitrate reductase in Bradyrhizobium japonicum.
The nitrate-sensing NasST system regulates nitrous oxide reductase and periplasmic nitrate reductase in Bradyrhizobium japonicum.
复制标题
硝酸盐感应 NasST 系统调节日本慢生根瘤菌中的一氧化二氮还原酶和周质硝酸盐还原酶。
DOI：
10.1111/1462-2920.12546
复制
发表时间：
2014
影响因子：
5.1
通讯作者：
and K. Minamisawa.
中科院分区：
文献类型：
--
作者：
Sanchez;C.;M. Itakura;T. Okubo;T. Matsumoto;H. Yoshikawa;A. Gotoh;M. Hidaka;T. Uchida;and K. Minamisawa.
大豆内共生菌大豆慢生根瘤菌（Bradyrhizobium japonicum）能通过N_2O还原酶（Nos）还原温室气体N_2O。在以往的研究中，大豆根际N2 O排放被B. japonicumNos++菌株（具有增加的Nos活性的突变体）减缓。在这里，我们报告的机制的NOS++表型。Nos++突变基因组的比较分析表明，bll 4572的突变导致Nos++表型。bll 4572编码NasS，双组分NasST调节系统的硝酸盐（NO3-）传感器。对nosZ（编码Nos）和nasSandnasST突变体反硝化过程中其他基因的转录分析表明，在没有NO3−的情况下，nasS突变诱导nosZandnap（周质硝酸还原酶）vianasT。NO3−的加入使NasS-NasT复合物在体外解离，表明激活剂NasT的释放。在NO3−存在下培养的细胞中，nasT的破坏导致innosZandnap转录显著减少。因此，尽管已知NasST调节细菌中NO3−同化基因的NO3−-介导的反应，但我们的结果表明，NasST调节了B. japonicum中来自异化反硝化途径的nosZandnapEgenes的NO3−-介导的反应。
The soybean endosymbiontBradyrhizobium japonicumis able to scavenge the greenhouse gas N2O through the N2O reductase (Nos). In previous research, N2O emission from soybean rhizosphere was mitigated byB. japonicumNos++strains (mutants with increased Nos activity). Here, we report the mechanism underlying the Nos++phenotype. Comparative analysis of Nos++mutant genomes showed that mutation ofbll4572resulted in Nos++phenotype.bll4572encodes NasS, the nitrate (NO3−)‐sensor of the two‐component NasST regulatory system. Transcriptional analyses ofnosZ(encoding Nos) and other genes from the denitrification process innasSandnasSTmutants showed that, in the absence of NO3−,nasSmutation inducesnosZandnap(periplasmic nitrate reductase) vianasT. NO3−addition dissociated the NasS‐NasT complexin vitro, suggesting the release of the activator NasT. Disruption ofnasTled to a marked decrease innosZandnaptranscription in cells incubated in the presence of NO3−. Thus, although NasST is known to regulate the NO3−‐mediated response of NO3−assimilation genes in bacteria, our results show that NasST regulates the NO3−‐mediated response ofnosZandnapEgenes, from the dissimilatory denitrification pathway, inB. japonicum.