Tintut Y, Wong C, Jiang Y, Hsieh M, Gralla J D
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024-1569.
Proc Natl Acad Sci U S A. 1994 Mar 15;91(6):2120-4. doi: 10.1073/pnas.91.6.2120.
sigma 54 is a rare bacterial protein that substitutes for sigma 70 in the case of Escherichia coli genes transcribed by certain activators with enhancer protein-like properties. It contains a strongly acidic region of previously unknown function. Gel mobility-shift assays using sigma 54 deletion mutants show that this region is essential for sigma 54 to bind the core RNA polymerase and recruit it to the promoter. Multiple-point mutational analysis shows that the acidic amino acids and overlapping periodic hydrophobic amino acids are necessary for this binding. Related sequences are not found within the core binding determinant of sigma 70, which binds the same core RNA polymerase. This comparison suggests that the core RNA polymerase interacts differently with the two sigma factors, likely contributing to the critical differences in transcription mechanism in the two cases.
σ54是一种罕见的细菌蛋白，在某些具有增强子蛋白样特性的激活因子转录大肠杆菌基因的情况下，它可替代σ70。它包含一个功能未知的强酸性区域。使用σ54缺失突变体进行的凝胶迁移率变动分析表明，该区域对于σ54结合核心RNA聚合酶并将其招募到启动子至关重要。多点突变分析表明，酸性氨基酸和重叠的周期性疏水氨基酸对于这种结合是必需的。在结合相同核心RNA聚合酶的σ70的核心结合决定簇内未发现相关序列。这种比较表明，核心RNA聚合酶与这两种σ因子的相互作用不同，这可能导致了两种情况下转录机制的关键差异。
