Disrupting hierarchical control of nitrogen fixation enables carbon-dependent regulation of ammonia excretion in soil diazotrophs.
Disrupting hierarchical control of nitrogen fixation enables carbon-dependent regulation of ammonia excretion in soil diazotrophs.
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破坏固氮的分级控制使土壤固氮生物中氨排泄的碳依赖性调节成为可能。
DOI：
10.1371/journal.pgen.1009617
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发表时间：
2021-06
期刊：
影响因子：
4.5
通讯作者：
Dixon R
中科院分区：
文献类型：
--
作者：
Bueno Batista M;Brett P;Appia-Ayme C;Wang YP;Dixon R
生物固氮的能量需求需要对这一过程进行严格的调控，以应对各种环境约束。为了确保固氮机制仅在适当的生理条件下表达，在变形菌中普遍存在的专用NifL-NifA调节系统在整合氧、碳和氮状态的信号以控制固氮（nif）基因的转录中起着至关重要的作用。对nif基因转录调控的复杂分子机制的更深入理解，可能为设计与谷物相关的固氮生物提供蓝图。在这项研究中，我们研究了一个单一的氨基酸取代NifA，（NifA-E356 K），破坏了层次的nif调节响应于固氮菌vinelandii的碳和氮的状态的属性。NifA-E356 K取代使得固氮酶在过量固定氮的存在下过表达并将氨释放到细胞外。然而，这两种性质都取决于碳源的性质。我们的研究表明，固氮作用与其同化作用的解偶联可能是谷氨酰胺合成酶反馈调节的结果，从而使多余的固定氮排出体外。来自其他变形菌的NifA中的相互取代产生了与A相似的性质。vinelandii对应物，表明这种变体蛋白可能有助于该家族不同成员之间的碳源依赖性氨排泄的工程化。NifL-NifA调节系统提供了专用的信号转导机制来调节不同变形菌中的固氮。了解氮和碳资源的平衡如何通过NifL-NifA发出信号，以精确控制固氮，可能会导致广泛适用的转化输出。在这里，我们描述了一种NifA变体，它绕过氮调节，但仍然依赖于碳状态，以使土壤固氮菌能够排泄氨。响应氮和碳的监管层次结构的中断表明如何整合环境刺激可以利用工程师的固定氮的有条件释放，以利于谷类作物。
The energetic requirements for biological nitrogen fixation necessitate stringent regulation of this process in response to diverse environmental constraints. To ensure that the nitrogen fixation machinery is expressed only under appropriate physiological conditions, the dedicated NifL-NifA regulatory system, prevalent in Proteobacteria, plays a crucial role in integrating signals of the oxygen, carbon and nitrogen status to control transcription of nitrogen fixation (nif) genes. Greater understanding of the intricate molecular mechanisms driving transcriptional control of nif genes may provide a blueprint for engineering diazotrophs that associate with cereals. In this study, we investigated the properties of a single amino acid substitution in NifA, (NifA-E356K) which disrupts the hierarchy of nif regulation in response to carbon and nitrogen status in Azotobacter vinelandii. The NifA-E356K substitution enabled overexpression of nitrogenase in the presence of excess fixed nitrogen and release of ammonia outside the cell. However, both of these properties were conditional upon the nature of the carbon source. Our studies reveal that the uncoupling of nitrogen fixation from its assimilation is likely to result from feedback regulation of glutamine synthetase, allowing surplus fixed nitrogen to be excreted. Reciprocal substitutions in NifA from other Proteobacteria yielded similar properties to the A. vinelandii counterpart, suggesting that this variant protein may facilitate engineering of carbon source-dependent ammonia excretion amongst diverse members of this family. The NifL-NifA regulatory system provides dedicated signal transduction machinery to regulate nitrogen fixation in diverse Proteobacteria. Understanding how the balance of nitrogen and carbon resources is signalled via NifL-NifA for precise control of nitrogen fixation may lead to broadly applicable translational outputs. Here, we characterize a NifA variant that bypasses nitrogen regulation but is still dependent on the carbon status to enable ammonia excretion in soil diazotrophs. Disruption of the regulatory hierarchy in response to nitrogen and carbon suggests how the integration of environmental stimuli could be harnessed to engineer conditional release of fixed nitrogen for the benefit of cereal crops.
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DOI：
10.1016/0304-4165(66)90383-7
发表时间：
1966-01-01
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
--
作者：
DILWORTH, MJ
通讯作者：
DILWORTH, MJ
影响因子：
6.9
作者：
Bloch，Sarah E.;Clark，Rosemary;Temme，Karsten
通讯作者：
Temme，Karsten
影响因子：
8.4
作者：
Federico Ortiz-Marquez, Juan Cesar;Do Nascimento, Mauro;Curatti, Leonardo
通讯作者：
Curatti, Leonardo
DOI：
10.1007/978-1-62703-625-2_14
发表时间：
2013-01-01
期刊：
SYNTHETI C BIOLOGY
影响因子：
--
作者：
Bikard, David;Mazel, Didier
通讯作者：
Mazel, Didier
影响因子：
4.4
作者：
Federico Ortiz-Marquez, Juan Cesar;Do Nascimento, Mauro;Curatti, Leonardo
通讯作者：
Curatti, Leonardo