Dandolo L, Blangy D
J Virol. 1980 Mar;33(3):927-35. doi: 10.1128/JVI.33.3.927-935.1980.
The influence of ionic strength on transcription of polyoma DNA by Escherichia coli RNA polymerase was investigated. At 0.15 M KCl, transcription was highly symmetrical and, due to the lack of reinitiation, a limited extent of RNA synthesis was observed. When the concentration of KCl was raised to 0.45 M, the affinity of the enzyme for its template, as well as its apparent affinity for ribonucleoside triphosphates, was reduced. Under optimal conditions, the rate and extent of RNA synthesis at 0.45 M KCl were greater than at 0.15 M KCl, and transcription was mostly asymmetric. Binding and initiation sites at both ionic strengths were identified; at 0.15 M KCl, transcription was initiated from two major sites, located at 0.99 and 0.06 map unit, whereas at 0.45 M KCl, a unique initiation site, at 0.99 map unit, was selected by RNA polymerase.
研究了离子强度对大肠杆菌RNA聚合酶转录多瘤病毒DNA的影响。在0.15M KCl条件下，转录高度对称，由于缺乏重新起始，观察到RNA合成的程度有限。当KCl浓度提高到0.45M时，酶对其模板的亲和力以及对核糖核苷三磷酸的表观亲和力均降低。在最佳条件下，0.45M KCl时RNA合成的速率和程度大于0.15M KCl时，且转录大多是不对称的。确定了两种离子强度下的结合位点和起始位点；在0.15M KCl时，转录从位于0.99和0.06图谱单位的两个主要位点起始，而在0.45M KCl时，RNA聚合酶选择了位于0.99图谱单位的一个独特起始位点。
