Positive and negative regulation of transferred nif genes mediated by indigenous GlnR in Gram-positive Paenibacillus polymyxa.
Positive and negative regulation of transferred nif genes mediated by indigenous GlnR in Gram-positive Paenibacillus polymyxa.
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革兰氏阳性多粘类芽孢杆菌中本土 GlnR 介导的转移 nif 基因的正向和负向调节
DOI：
10.1371/journal.pgen.1007629
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发表时间：
2018-09
期刊：
影响因子：
4.5
通讯作者：
Li J
中科院分区：
文献类型：
--
作者：
Wang T;Zhao X;Shi H;Sun L;Li Y;Li Q;Zhang H;Chen S;Li J
氨是大多数固氮生物中调节固氮的主要信号。在革兰氏阴性固氮菌中，氨对固氮的调节是很好的。在这些细菌中，这种调节主要发生在nif（固氮）基因转录的水平上，这需要一种nif特异性激活剂NifA。虽然革兰氏阳性和固氮类芽孢杆菌已被广泛用作农业中的细菌肥料，但如何响应这些细菌中的氮可用性来调节固氮仍不清楚。一个土著GlnR和GlnR/TnrA结合位点的启动子区的nif集群是保守的，在这些菌株中，表明GlnR作为一个调节器的固氮作用。在这项研究中，我们首次揭示了多粘类芽孢杆菌WLY 78的GlnR是氮限制下nif基因转录所必需的，而GlnRA操纵子中glnA编码的GlnR和谷氨酰胺合成酶（GS）都是在过量氮下抑制nif表达所必需的。GlnR的二聚化是GlnR与DNA结合所必需的。GlnR在P.polymyxaWLY78中以二聚体和单体的混合物存在。GlnR单体的C-末端区域是阻止GlnR结合DNA的自抑制结构域。两个GlnR结合位点位于nif操纵子（nifBHDKENXhesAnifV）的nif启动子的-35/-10区域的侧翼。GlnR结合位点Ⅰ（位于nif启动子的-35/-10区上游）是激活nif转录所必需的，而GlnR结合位点Ⅱ（位于nif启动子的-35/-10区下游）是抑制nif表达所必需的。在氮限制条件下，GlnR二聚体与GlnR结合位点Ⅰ以弱的、短暂的结合方式结合，激活nif转录。在过量氮期间，谷氨酰胺通过形成复合物FBI-GS结合并反馈抑制GS。FBI-GS与GlnR的C端结构域相互作用，稳定GlnR与GlnR结合位点Ⅱ的结合亲和力，从而抑制nif的转录。
Ammonia is a major signal that regulates nitrogen fixation in most diazotrophs. Regulation of nitrogen fixation by ammonia in the Gram-negative diazotrophs is well-characterized. In these bacteria, this regulation occurs mainly at the level of nif (nitrogen fixation) gene transcription, which requires a nif-specific activator, NifA. Although Gram-positive and diazotrophic Paenibacilli have been extensively used as a bacterial fertilizer in agriculture, how nitrogen fixation is regulated in response to nitrogen availability in these bacteria remains unclear. An indigenous GlnR and GlnR/TnrA-binding sites in the promoter region of the nif cluster are conserved in these strains, indicating the role of GlnR as a regulator of nitrogen fixation. In this study, we for the first time reveal that GlnR of Paenibacillus polymyxa WLY78 is essentially required for nif gene transcription under nitrogen limitation, whereas both GlnR and glutamine synthetase (GS) encoded by glnA within glnRA operon are required for repressing nif expression under excess nitrogen. Dimerization of GlnR is necessary for binding of GlnR to DNA. GlnR in P. polymyxa WLY78 exists in a mixture of dimers and monomers. The C-terminal region of GlnR monomer is an autoinhibitory domain that prevents GlnR from binding DNA. Two GlnR-biding sites flank the -35/-10 regions of the nif promoter of the nif operon (nifBHDKENXhesAnifV). The GlnR-binding site Ⅰ (located upstream of -35/-10 regions of the nif promoter) is specially required for activating nif transcription, while GlnR-binding siteⅡ (located downstream of -35/-10 regions of the nif promoter) is for repressing nif expression. Under nitrogen limitation, GlnR dimer binds to GlnR-binding siteⅠ in a weak and transient association way and then activates nif transcription. During excess nitrogen, glutamine binds to and feedback inhibits GS by forming the complex FBI-GS. The FBI-GS interacts with the C-terminal domain of GlnR and stabilizes the binding affinity of GlnR to GlnR-binding site Ⅱ and thus represses nif transcription.
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影响因子：
4.8
作者：
Hauf, Ksenia;Kayumov, Airat;Forchhammer, Karl
通讯作者：
Forchhammer, Karl
DOI：
10.1590/s0100-879x2011007500138
发表时间：
2011-12-01
影响因子：
2.3
作者：
Castellen, P.;Rego, F.G.M.;Benelli, E.M.
通讯作者：
Benelli, E.M.
模因套件：用于发现和搜索的工具。
影响因子：
14.9
作者：
Bailey TL;Boden M;Buske FA;Frith M;Grant CE;Clementi L;Ren J;Li WW;Noble WS
通讯作者：
Noble WS
影响因子：
3.7
作者：
Sarkar A;Reinhold-Hurek B
通讯作者：
Reinhold-Hurek B
影响因子：
3.2
作者：
Mäder, U;Hennig, S;Homuth, G
通讯作者：
Homuth, G