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首页> 外文期刊>Journal of Molecular Biology >ACTIVATION OF RPOS-DEPENDENT PROP P2 TRANSCRIPTION BY THE FIS PROTEIN IN VITRO
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ACTIVATION OF RPOS-DEPENDENT PROP P2 TRANSCRIPTION BY THE FIS PROTEIN IN VITRO

机译：FIS蛋白质体外激活与RPOS有关的Prop P2转录

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The proP gene, encoding a transporter of the osmoprotecting compounds proline and glycine betaine, is expressed from two promoters. Transcription of the P2 promoter occurs at a transient period in late exponential phase and is dependent upon Fis and the RpoS (sigma(38)) sigma factor. Here we characterize Fis-mediated activation of the P2 promoter in vitro. We find that this promoter displays unusually high specificity for sigma(38). Fis strongly activates P2 when bound to site I centered at -41 within the promoter region. There is a complex relationship involving DNA supercoiling and potassium glutamate concentration on Fis activation, but most efficient transcription occurs under high salt conditions when the superhelical density is above -0.03. The major stimulatory effect of DNA supercoiling occurs between superhelical densities of 0 to -0.02 suggesting that, while supercoiling is mechanistically important, it may not be a physiologically relevant controlling factor. However, the stimulation of transcription by high potassium glutamate concentrations may contribute to the osmotic inducibility of the P2 promoter. We show that Fis and E sigma(38) bind cooperatively on supercoiled DNA to form a stable complex at P2 that involves promoter melting. Fis also binds to a second site within the proP regulatory region. While binding to this site appears to play no role in Fis activation of the P2 promoter, it functions as repressor of transcription initiating from the P1 promoter by either sigma(70) or sigma(38). (C) 1997 Academic Press Limited. [References: 61]
机译：从两个启动子表达编码渗透保护化合物脯氨酸和甘氨酸甜菜碱的转运蛋白的proP基因。 P2启动子的转录发生在指数后期的过渡时期，并且取决于Fis和RpoS（sigma（38））sigma因子。在这里，我们表征了Fis介导的P2启动子的体外激活。我们发现该启动子对sigma（38）具有异常高的特异性。当与启动子区域内以-41为中心的位点I结合时，Fis强烈激活P2。涉及DNA超螺旋和谷氨酸钾浓度对Fis激活存在复杂的关系，但是当超螺旋密度高于-0.03时，最有效的转录发生在高盐条件下。 DNA超螺旋的主要刺激作用发生在0到-0.02的超螺旋密度之间，这表明，尽管超螺旋在机械上很重要，但它可能不是生理相关的控制因素。但是，高谷氨酸钾浓度对转录的刺激可能有助于P2启动子的渗透诱导性。我们显示，Fis和E sigma（38）在超螺旋DNA上合作结合，在P2处形成涉及启动子融化的稳定复合物。 Fis还与proP调节区内的第二个位点结合。虽然与该位点的结合似乎在P2启动子的Fis激活中不起作用，但它起着σ（70）或σ（38）从P1启动子开始的转录阻遏物的作用。 （C）1997 Academic Press Limited。 [参考：61]

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