Hanamura A, Aiba H
Institute of Biological Sciences, University of Tsukuba, Ibaraki, Japan.
Nucleic Acids Res. 1991 Aug 25;19(16):4413-9. doi: 10.1093/nar/19.16.4413.
Transcription of the Escherichia coli crp gene encoding cAMP receptor protein (CRP) is negatively regulated by CRP-cAMP complex that binds to a specific site located downstream from the transcription start site. The binding of CRP-cAMP to this site activates transcription from a second divergent overlapping promoter. The mechanism of this negative autoregulation of the crp gene has been investigated by in vitro transcription, gel shift, DNase I footprinting, and exonuclease III protection assays. We demonstrated that the crp and divergent promoters are reciprocally and coordinately regulated by CRP-cAMP. The abortive initiation assay revealed that the divergent RNA itself is not required for the inhibition of crp transcription. Detailed binding studies revealed that CRP-cAMP stimulates the binding of RNA polymerase to the divergent promoter and thus blocks the occupation of the crp promoter by RNA polymerase.
编码环磷酸腺苷受体蛋白（CRP）的大肠杆菌crp基因的转录受到CRP - cAMP复合物的负调控，该复合物与位于转录起始位点下游的特定位点结合。CRP - cAMP与该位点的结合激活了来自第二个反向重叠启动子的转录。通过体外转录、凝胶迁移、DNase I足迹分析和核酸外切酶III保护分析对crp基因这种负自调控的机制进行了研究。我们证明crp和反向启动子受到CRP - cAMP的相互协调调控。流产起始分析表明，反向RNA本身对于抑制crp转录并非必需。详细的结合研究表明，CRP - cAMP刺激RNA聚合酶与反向启动子的结合，从而阻止RNA聚合酶占据crp启动子。
