Altuvia S, Almirón M, Huisman G, Kolter R, Storz G
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892.
Mol Microbiol. 1994 Jul;13(2):265-72. doi: 10.1111/j.1365-2958.1994.tb00421.x.
Dps is a non-specific DNA-binding protein abundant in starved Escherichia coli cells and is important for the defence against hydrogen peroxide. We found that dps mRNA levels are controlled by rpoS-encoded sigma S, the transcriptional activator OxyR and the histone-like IHF protein. In exponentially growing cells, dps is induced by treatment with hydrogen peroxide in an OxyR-dependent manner. This OxyR-dependent induction occurs only during log phase, although the OxyR protein is present in stationary phase. In the stationary phase cells, dps is expressed in a sigma S- and IHF-dependent manner. The purified OxyR and IHF proteins are also shown to bind upstream of the dps promoter. Our results suggest that the dps promoter is recognized by both sigma 70-holoenzyme and sigma S-holoenzyme, since OxyR acts through sigma 70 and the starts of the OxyR- and sigma S-dependent transcripts are identical.
Dps是一种在饥饿的大肠杆菌细胞中大量存在的非特异性DNA结合蛋白，对抵御过氧化氢至关重要。我们发现dps mRNA水平受rpoS编码的σS、转录激活因子OxyR和类组蛋白IHF蛋白调控。在指数生长期的细胞中，过氧化氢处理以OxyR依赖的方式诱导dps表达。这种OxyR依赖的诱导仅在对数期发生，尽管OxyR蛋白在稳定期也存在。在稳定期细胞中，dps以σS和IHF依赖的方式表达。纯化的OxyR和IHF蛋白也被证明能结合在dps启动子上游。我们的结果表明dps启动子可被σ70全酶和σS全酶识别，因为OxyR通过σ70起作用，且OxyR依赖和σS依赖转录本的起始位点相同。
