Igarashi K, Fujita N, Ishihama A
Department of Molecular Genetics, National Institute of Genetics, Shizuoka, Japan.
Nucleic Acids Res. 1989 Nov 11;17(21):8755-65. doi: 10.1093/nar/17.21.8755.
Transcription in vitro of stringently controlled Escherichia coli genes by purified RNA polymerase holoenzyme is inhibited by guanosine tetraphosphate (ppGpp). In order to examine possible role of omega factor in this ppGpp sensitivity, RNA polymerases with or without the omega factor were reconstituted and tested for their ppGpp sensitivity using an in vitro mixed transcription system. RNA polymerase lacking the omega factor was found virtually insensitive to ppGpp but the addition of a purified omega factor restored the ppGpp sensitivity of this omega-free RNA polymerase. These results raise a possibility that the omega factor is a regulatory protein of RNA polymerase and is involved in the ppGpp-mediated alteration of the promoter selectivity.
鸟苷四磷酸（ppGpp）可抑制纯化的RNA聚合酶全酶对严格调控的大肠杆菌基因进行的体外转录。为了研究ω因子在这种对ppGpp敏感性中的可能作用，重组了含或不含ω因子的RNA聚合酶，并使用体外混合转录系统测试它们对ppGpp的敏感性。发现缺乏ω因子的RNA聚合酶对ppGpp几乎不敏感，但添加纯化的ω因子可恢复这种不含ω因子的RNA聚合酶对ppGpp的敏感性。这些结果提示，ω因子可能是RNA聚合酶的一种调节蛋白，并参与ppGpp介导的启动子选择性改变。
