Contributions of Sinorhizobium meliloti Transcriptional Regulator DksA to Bacterial Growth and Efficient Symbiosis with Medicago sativa
Contributions of Sinorhizobium meliloti Transcriptional Regulator DksA to Bacterial Growth and Efficient Symbiosis with Medicago sativa
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苜蓿中华根瘤菌转录调节因子 DksA 对细菌生长及与苜蓿高效共生的贡献
DOI：
10.1128/jb.00013-16
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发表时间：
2016
影响因子：
3.2
通讯作者：
S. R. Long
中科院分区：
文献类型：
--
作者：
K. Wippel;S. R. Long
这种由(P)ppGpp合成酶relA和RNA聚合酶结合蛋白DksA介导的严格反应是由有限的营养条件触发的。对于一些细菌来说，它参与了毒力的调节。我们研究了来自革兰氏阴性固氮共生菌苜蓿中华根瘤菌的两个类Dks A蛋白在自由生活培养中的作用以及与其宿主紫花苜蓿相互作用的作用。这两个并列基因由SMc00469和SMc00049基因编码，在规范Dks A中功能所需的两个主要结构域的组成上有所不同：位于螺旋线圈结构域顶端的DXXDXA基序和锌指结构域。通过对SMc00469(指定为dks A)、Smc 00049和ΔA的单、双和三个缺失的突变分析，我们发现，Δdks突变体而不是relA突变体在最低限度的培养基上表现出生长障碍，寄主植物上的结瘤减少，早期根瘤的固氮活性降低，而其结瘤基因表达正常。Δ相关突变体在所有测试条件下都表现出严重的多效性。只有草甘链霉菌A补充了大肠杆菌dks A突变体的代谢缺陷。对SMc00049中DXXDXA基序的修改未能建立DksA功能。我们的结果暗示了转录调控因子DksA在苜蓿链霉菌中的作用。严格的反应是由营养胁迫引发的细菌转录调控过程。紫花苜蓿根瘤菌是一种与豆科植物建立重要根瘤共生关系的土壤细菌，在寄主相互作用过程中经历不断的分子调节。分析这种甲型蛋白细菌中严格反应的成分有助于理解关于植物相互作用发展的分子控制。利用突变分析，我们描述了Dks A的缺乏如何影响与紫花苜蓿的共生，并表明第二个近缘的紫花苜蓿蛋白不能取代这一缺失的功能。这项工作通过展示苜蓿链霉菌DksA类似蛋白与其他物种的同源物的相似性和差异，为严格的反应调控系统的多样性增加了信息。
The stringent response, mediated by the (p)ppGpp synthetase RelA and the RNA polymerase-binding protein DksA, is triggered by limiting nutrient conditions. For some bacteria, it is involved in regulation of virulence. We investigated the role of two DksA-like proteins from the Gram-negative nitrogen-fixing symbiont Sinorhizobium meliloti in free-living culture and in interaction with its host plant Medicago sativa. The two paralogs, encoded by the genesSMc00469andSMc00049, differ in the constitution of two major domains required for function in canonical DksA: the DXXDXA motif at the tip of a coiled-coil domain and a zinc finger domain. Using mutant analyses of single, double, and triple deletions forSMc00469(designateddksA),SMc00049, andrelA, we found that the ΔdksAmutant but not the ΔSMc00049mutant showed impaired growth on minimal medium, reduced nodulation on the host plant, and lower nitrogen fixation activity in early nodules, while itsnodgene expression was normal. The ΔrelAmutant showed severe pleiotropic phenotypes under all conditions tested. Only S. melilotidksAcomplemented the metabolic defects of an Escherichia coli dksA mutant. Modifications of the DXXDXA motif in SMc00049 failed to establish DksA function. Our results imply a role for transcriptional regulator DksA in the S. meliloti-M. sativa symbiosis.IMPORTANCEThe stringent response is a bacterial transcription regulation process triggered upon nutritional stress. Sinorhizobium meliloti, a soil bacterium establishing agriculturally important root nodule symbioses with legume plants, undergoes constant molecular adjustment during host interaction. Analyzing the components of the stringent response in this alphaproteobacterium helps understand molecular control regarding the development of plant interaction. Using mutant analyses, we describe how the lack of DksA influences symbiosis with Medicago sativa and show that a second paralogous S. meliloti protein cannot substitute for this missing function. This work contributes to the field by showing the similarities and differences of S. meliloti DksA-like proteins to orthologs from other species, adding information to the diversity of the stringent response regulatory system.
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DOI：
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发表时间：
--
期刊：
--
影响因子：
--
作者：
K. Livak;Thomas D. Schmittgen
通讯作者：
K. Livak;Thomas D. Schmittgen
DOI：
10.1038/nbt0184-81
发表时间：
1984-01-01
期刊：
BIO-TECHNOLOGY
影响因子：
--
作者：
MASUI, Y;MIZUNO, T;NOUYE, M
通讯作者：
NOUYE, M
影响因子：
3.6
作者：
Griffitts, Joel S.;Carlyon, Rebecca E.;Long, Sharon R.
通讯作者：
Long, Sharon R.
影响因子：
3.2
作者：
Pal, Ritesh Ranjan;Bag, Satyabrata;Bhadra, Rupak K.
通讯作者：
Bhadra, Rupak K.
影响因子：
5.4
作者：
Liu K;Bittner AN;Wang JD
通讯作者：
Wang JD