Tjian R, Losick R, Pero J, Hinnebush A
Eur J Biochem. 1977 Mar 15;74(1):149-54. doi: 10.1111/j.1432-1033.1977.tb11376.x.
Bacillus subtilis delta protein is a 21 500-Mr polypeptide that can be isolated in association with RNA polymerase holoenzyme from uninfected bacteria and with modified forms of RNA polymerase from cells infected with phage SP01 [Pero, J., Nelson, J. and Fox, T. (1975) Proc. Natl Acad. Sci. U.S.A. 72,1589]. Although no function has been assigned to delta protein in uninfected cells, this host polypeptide enhances the specificity of transcription by phage-modified forms of RNA polymerase that contain SP01-coded regulatory subunits. This report describes the purification of delta and sigma proteins from uninfected B. subtilis and examines the comparative effects of these polypeptides on transcription by core RNA polymerase. Purified sigma polypeptide was found to stimulate the transcription of phage DNA while having little effect on RNA synthesis with the synthetic DNA poly(dA-dT) as template. In contrast, purified delta protein markedly depressed the transcription of poly(dA-dT) while having little effect on enzyme activity with phage DNA as template. The inhibitory effect of delta protein on poly (dA-dT) transcription was strongly dependent on the presence of KC1 in the RNA synthesis reaction mixture.
枯草芽孢杆菌δ蛋白是一种分子量为21500的多肽，它可以与未感染细菌的RNA聚合酶全酶以及感染噬菌体SP01的细胞中修饰形式的RNA聚合酶一起分离出来[佩罗，J.，纳尔逊，J.和福克斯，T.（1975年）《美国国家科学院院刊》72，1589]。虽然在未感染的细胞中尚未赋予δ蛋白任何功能，但这种宿主多肽可增强含有SP01编码调节亚基的噬菌体修饰形式的RNA聚合酶的转录特异性。本报告描述了从未感染的枯草芽孢杆菌中纯化δ蛋白和σ蛋白，并研究了这些多肽对核心RNA聚合酶转录的比较影响。发现纯化的σ多肽可刺激噬菌体DNA的转录，而以合成DNA聚（ dA - dT）为模板时对RNA合成几乎没有影响。相反，纯化的δ蛋白显著抑制聚（ dA - dT）的转录，而以噬菌体DNA为模板时对酶活性几乎没有影响。δ蛋白对聚（ dA - dT）转录的抑制作用强烈依赖于RNA合成反应混合物中KCl的存在。
