NifL-NifA固氮转录调控系统的研究进展  

Transcriptional regulation of nitrogen fixation by the NifL-NifA system

作　　者：王语涵 高宇 王丰 梅子青 WANG Yuhan;GAO Yu;WANG Feng;MEI Ziqing(Key Laboratory of Molecular Medicine and Biotherapy,Department of Biological Sciences,School of Life Science,Beijing Institute of Technology,Beijing 100081,China;School of Chemistry and Biological Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京理工大学生命学院,分子医学与生物诊疗工业和信息化部重点实验室,北京100081 [2]北京科技大学化学与生物工程学院,北京100083

出　　处：《生命的化学》2021年第9期1935-1943,共9页Chemistry of Life

基　　金：国家自然科学基金面上项目(31870791)。

摘　　要：固氮菌中有序、高效的生物固氮过程由复杂的分子机制调控。在自生固氮菌中,NifL-NifA二元系统通过感知细胞的氧化还原信号和能量状态实现对nif基因簇转录的精细调控,进而参与生物固氮的调控。当固氮菌处于厌氧微环境和氮缺乏条件下时,nif基因的转录激活蛋白NifA与RNAP-σ54全酶结合,激活nif基因簇的转录,促进固氮酶的合成。在有氧或氮充足条件下,NifL与NifA发生直接相互作用,抑制NifA的转录激活功能。此外,作为感受细胞氮水平的PⅡ蛋白GlnK分子,通过其共价修饰的尿苷酰化的转变参与NifL-NifA系统的转录调控。本文以模式生物棕色固氮菌为例探讨了自生固氮菌的nif基因转录调控机制,为自生固氮调控研究提供了初步的综合性数据。The orderly and efficient biological nitrogen fixation process in diazotrophic bacteria is regulated by complicated molecular mechanisms. In free-living diazotrophic bacteria, the NifL-NifA system regulates the nif gene clusters transcription subtly by sensing redox signal and energy state in the cells. When nitrogenfixing bacteria are in the anaerobic microenvironment and lack of nitrogen, NifA binds to RNAP-σ54 holoenzyme to activate the transcriptional initiation of the nif gene clusters and promote the synthesis of nitrogenase. However, in the presence of oxgen or nitrogen being sufficient, NifL interacts directly with NifA,inhibiting NifA from activating transcription. In addition, GlnK, as a PⅡ protein that senses cellular nitrogen level, participates in the transcriptional regulation of the NifL-NifA system through transition of its uridine modification. In this review, we take the model organism Azotobacter vinelandii as an example to discuss the regulation mechanism of nif gene transcription of free-living diazotrophic bacteria, and provide preliminary comprehensive insight into free-living nitrogen fixation regulation.

关 键 词：生物固氮 NifL NIFA GLNK 

分 类 号：Q933[生物学—微生物学]