天冬氨酸转氨酶在中慢生根瘤菌MAFF303099共生固氮中的作用  

Role of aspartate aminotoransferase in symbiotic nitrogen fixation of Mesobrorhizobium MAFF

作　　者：王婧仪 曹扬荣 朱辉[1] WANG Jingyi;CAO Yangrong;ZHU Hui(State Key Laboratory of Agricultural Microbiology/College of Life Sciences and Technology,Huazhong Agricultural University,Wuhan 430070,China)

机构地区：[1]农业微生物学国家重点实验室/华中农业大学生命科学技术学院,武汉430070

出　　处：《华中农业大学学报》2021年第6期68-74,共7页Journal of Huazhong Agricultural University

基　　金：国家自然科学基金项目(32070273);国家重点研发计划项目(2019YFA0904700)。

摘　　要：为寻找根瘤菌中与共生固氮相关的调控基因,采用同源重组法,分别敲除中慢生根瘤菌MAFF303099在与豆科植物百脉根共生固氮过程上调表达的10个基因,研究它们对共生固氮的影响。结果显示:Δmlr5883敲除突变体相比于野生型MAFF303099,其固氮酶活性下降40%,侵染细胞形态未发生显著改变,对Δmlr5883回补可恢复固氮酶活性;预测mlr5883编码天冬氨酸氨基转移酶,体外检测该酶的天冬氨酸转氨酶活性为16.67 U/mg。该基因的突变会影响固氮效率,推测其可能参与对植物供给碳源的代谢过程。In order to find the regulatory genes related to symbiotic nitrogen fixation in rhizobia,homologous recombination was used to knock out 10 up-regulated genes during the symbiotic nitrogen fixation of Lotus japonicus and Rhizobium MAFF303099.The results showed that the nitrogenase activity of theΔmlr5883 was 40%lower than that of the wild-type MAFF303099.The morphology of infected cells did not change significantly,and replenishing mlr5883 restored nitrogenase activity.It is predicted that mlr5883 encodes an aspartate aminotransferase.The aspartate aminotransferase activity of this MLR5883 was 16.67 U/mg in vitro.The mutation of mlr5883 affected the efficiency of nitrogen fixation,indicating that it may be involved in the metabolic process of supplying carbon sources to plants.

关 键 词：天冬氨酸转氨酶 中慢生根瘤菌MAFF303099 共生固氮 同源重组 

分 类 号：Q939.9[生物学—微生物学]