摘要
本文研究了巴西固氮螺菌(Azospirillum brasilense)“玉-62”在以谷氨酸为氮源的好气液体培养条件下固氮酶活性厌氧关闭的机制。ATP 合成的解偶联剂 CCCP 使固氮酶迅速失活,Western blotting 实验证明这种失活的分子基础是固氮酶铁蛋白—亚基被修饰。用萤光素-萤光素酶法测定表明厌氧处理使细胞内 ATP/ADP 比值迅速下降,固氮酶活性亦迅速被抑制,重新供氧后细胞内 ATP/ADP 比值很快恢复到原水平,固氮酶活性亦迅速上升。CCCP处理亦使细胞内 ATP/ADP 比值迅速下降。低电位电子受体 Metronidazole 制固氮活性,但固氮酶铁蛋白不被修饰,细胞内 ATP/ADP 比值略上升。实验证明,细胞内 ATP/ADP 比值的变化是启动固氮酶铁蛋白修饰系统的信号分子。
Anaerobic switch-off of Nase activity in A.brasilense“Yu-62”cultured aerobically in li- quid medium with glutamic acid as N source was described.CCCP inactivated Nase rapidly.We- stern blotting experiment demonstrated that the molecular basis of inactivation of Nase was the modification of the Fe protein subunit.The anaerobic condition reduced ATP/ADP ratio in the cells and switched-off the Nase activity.The restoration of aerobic condition gave rise to ra- pid increase of ATP/ADP ratio and Nase activity.CCCP reduced ATP/ADP ratio rapidly.Me- tronidazole,a low potential electron acceptor,inhibited Nase activity but has no effect on mo- dification of Fe protein,however,caused a slight change of ATP/ADP ratio.Our experiments demonstrated that the change of ATP/ADP ratio in ceils was a signal trigging the modifica- tion of Fe protein.
基金
863项目
关键词
生物固氮
固氮螺菌
固氮酶
Nasw activity
Anaerobic switch-off
ATP/ADP ratio
Azospirillum brasilense
