Studies on the roles of GlnK and GlnB in regulating Klebsiella pneumoniae NifL-dependent nitrogen control
Studies on the roles of GlnK and GlnB in regulating Klebsiella pneumoniae NifL-dependent nitrogen control
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DOI：
10.1111/j.1574-6968.1999.tb08805.x
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发表时间：
1999-11-15
影响因子：
2.1
通讯作者：
Merrick, M
中科院分区：
文献类型：
--
作者：
Arcondéguy, T;van Heeswijk, WC;Merrick, M
在肺炎克雷伯菌中，固氮（nif）基因是根据固定的氮和氧进行调控的。nif特异性转录激活因子NifA的活性由NifL调节，NifL介导氧和氮的调控。当细胞内N水平高时，需要信号转导蛋白GlnK来缓解NifL和NifA的抑制作用，在野生型细胞中，GlnK的作用不能被结构相关蛋白PII所取代。我们研究了NifL在以大肠杆菌为宿主的异源系统中对NifA活性的调节。使用Delta glnB，Delta glnK突变体，我们已经证明NifL对NifA活性的调节依赖于细胞中glnK的浓度，并且当过量产生时，PII可以替代glnK。此外，我们的数据表明，PII可以抵消GlnK在缓解NifA活性依赖抑制中的积极作用。当细胞内氮水平升高时，PII的这种负面作用可能在抑制nif基因表达方面具有重要的生理意义。(C) 1999年欧洲微生物学会联合会。Elsevier Science B.V.版权所有。
In Klebsiella pneumoniae, nitrogen fixation (nif) genes are regulated in response to fixed nitrogen and oxygen. The activity of the nif-specific transcriptional activator NifA is modulated by NifL, which mediates both oxygen and nitrogen control. The signal transduction protein GlnK is required to relieve the inhibitory effect of NifL an NifA that occurs when the intracellular N status is high and in a wild-type cell, the action of GlnK cannot be substituted by the structurally related protein PII. We have studied the modulation of NifA activity by NifL in an heterologous system in which the host organism is Escherichia coli. Using a Delta glnB,Delta glnK mutant, we have shown that the modulation of NifA activity by NifL is dependent on the concentration of GlnK in the cell and that when overproduced, PII can substitute for GlnK. Furthermore, our data suggest that PII can counteract the positive action of GlnK in relieving NifL-dependent inhibition of NifA activity. This negative effect of PII may be physiologically important in establishing repression of nif gene expression when the intracellular nitrogen status rises. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.