Regulation of nitrogen metabolism in Azotobacter vinelandii: isolation of ntr and glnA genes and construction of ntr mutants.
Regulation of nitrogen metabolism in Azotobacter vinelandii: isolation of ntr and glnA genes and construction of ntr mutants.
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DOI：
10.1002/j.1460-2075.1986.tb04225.x
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发表时间：
1986-02
期刊：
影响因子：
--
通讯作者：
A. Toukdarian;C. Kennedy
中科院分区：
文献类型：
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作者：
A. Toukdarian;C. Kennedy
ntrA， ntrB和ntrC产物负责调节许多参与肠道细菌同化贫氮源的基因的转录。本文报道了在非肠道细菌中存在的类似系统。通过与大肠杆菌突变体的互补，从A. vinelandii基因文库中分离出与ntrA和ntrC相似的基因。编码谷氨酰胺合成酶的基因glnA也被分离出来，发现它与ntrC相邻，但远离ntrA，就像在肠道生物中一样。克隆的固氮菌基因也与肺炎克雷伯菌突变体互补，并与肺炎克雷伯菌ntrA、ntrC和glnA基因探针杂交。通过在克隆基因中插入Tn5，通过标记交换构建突变体，确定了ntrA和ntrC在黄花沙蚕中的作用。这些突变体表明ntrA和ntrC都是利用硝酸盐作为氮源所必需的。然而，A. vinelandii不需要ntrC进行固氮，而肺炎克雷伯菌则需要ntrA和ntrC。
The ntrA, ntrB and ntrC products are responsible for regulating the transcription of many genes involved in the assimilation of poor nitrogen sources in enteric bacteria. The presence of a similar system in the non‐enteric bacterium Azotobacter vinelandii is reported here. Genes analogous to ntrA and ntrC were isolated from an A. vinelandii gene library by complementation of Escherichia coli mutants. The gene encoding glutamine synthetase, glnA, was also isolated and found to be adjacent to ntrC but distant from ntrA, as it is in enteric organisms. The cloned Azotobacter genes also complemented Klebsiella pneumoniae mutants and hybridized to K. pneumoniae ntrA, ntrC and glnA gene probes. The role of ntrA and ntrC in A. vinelandii was established by using Tn5 insertions in the cloned genes to construct mutants by marker exchange. These mutants show that both ntrA and ntrC are required for the utilization of nitrate as a nitrogen source. However, ntrC is not required for nitrogen fixation by A. vinelandii, in contrast with K. pneumoniae where both ntrA and ntrC are essential.