阴沟肠杆菌nifL对nifA蛋白激活固氮基因表达的影响  

The Influence of the Enterobacter cloacae Gene nifL upon NifA Activating Transcription of Nitrogen Fixation Genes

作　　者：沈炳福 邱德义[2] 周晓媛 

机构地区：[1]中国科学院上海植物生理研究所 [2]上海市计划生育科学研究所,上海200032

出　　处：《植物生理学报（0257-4829)》2000年第4期289-292,共4页Acta Phytophysiologica Sinica

基　　金：国家863基金资助项目

摘　　要：通过基因定位突变的方法 ,构建了阴沟肠杆菌E2 6染色体上基因nifL突变菌E11和E12 ,并对其固氮特性进行分析。结果显示 ,当细菌在有NH+4 的条件下 ,nifL作为固氮基因的负调节因子 ,可能是通过nifL蛋白与nifA蛋白之间的相互作用 ,形成某种复合物 ,导致NifA的失活 ,从而关闭nif基因的表达。高温条件下 (37℃ ) ,nifL并不参与对nif基因表达的阻遏作用 。E. cloacae E26 is a nitrogen fixing bacterium in the rhizosphere of rice plants grown in subtropical regions. Nitrogen fixation in E. cloacae could proceed at a high temperature (37℃). The nifL mutants (E11 and E12) were constructed by in vitro insertion of a tetracycline resistant (Tc r) gene into the Sma Ⅰ site located in the nifL gene (Fig.1) and by in vivo two point crossing over based on homologous recombination. Using E. cloacae nifL mutant strains and several different methods of analysis, we have shown that NH + 4 repression of nif gene transcription by the nifL might be involved in an interaction between NifL and NifA. The positive regulatory function of NifA could be inhibited by NifL in response to combined nitrogen (Table 2). Investigation of temperature repression has indicated that NifL does not act as a repressor in response to high temperature. At 37℃, NifL mutants E11 and E12 were derepressed to a lesser extent than does the wild type strain which is probably due to an increased temperature sensitivity of NifA in the absence of functional NifL (Table 3).

关 键 词：基因调节 nirL nirA 阴沟肠杆菌 固氮基因 

分 类 号：Q74[生物学—分子生物学]