Premakumar R, Pau R N, Mitchenall L A, Easo M, Bishop P E
U.S. Department of Agriculture, and Department of Microbiology, North Carolina State University, Raleigh 27695-7615, USA.
FEMS Microbiol Lett. 1998 Jul 1;164(1):63-8. doi: 10.1111/j.1574-6968.1998.tb13068.x.
Transcription of the genes encoding molybdenum (Mo)-independent nitrogenases 2 and 3 of Azotobacter vinelandii requires the activators VnfA and AnfA, respectively. The effect of NH4+, Mo, or V (vanadium) was tested on the expression of vnfA-lacZ and anfA-lacZ transcriptional fusions. Mo repressed expression of both fusions whereas NH4+ and V repressed the anfA-lacZ fusion, but not the vnfA-lacZ fusion. Thus the repressive effect on transcription of the anfHDGKOR operon by NH4+, Mo, or V is mediated through their effect on transcription of anfA and the repressive effect of Mo on the vnfHFd and vnfDGK operons is mediated through Mo repression of vnfA transcription. Mo-dependent repression of anfA transcription is influenced but not entirely mediated by the Mo-responsive regulator ModE.
编码维涅兰德固氮菌钼（Mo）非依赖型固氮酶2和3的基因转录分别需要激活因子VnfA和AnfA。测试了NH4+、Mo或V（钒）对vnfA-lacZ和anfA-lacZ转录融合体表达的影响。Mo抑制了两种融合体的表达，而NH4+和V抑制了anfA-lacZ融合体，但不抑制vnfA-lacZ融合体。因此，NH4+、Mo或V对anfHDGKOR操纵子转录的抑制作用是通过它们对anfA转录的影响介导的，而Mo对vnfHFd和vnfDGK操纵子的抑制作用是通过Mo对vnfA转录的抑制介导的。Mo依赖的对anfA转录的抑制受到Mo响应调节因子ModE的影响，但并非完全由其介导。
