Changes in the DNA structure of the lac UV5 promoter during formation of an open complex with Escherichia coli RNA polymerase.
Changes in the DNA structure of the lac UV5 promoter during formation of an open complex with Escherichia coli RNA polymerase.
复制标题
与大肠杆菌 RNA 聚合酶形成开放复合物期间 lac UV5 启动子 DNA 结构的变化。
作者：
A. Spassky;K. Kirkegaard;H. Buc
通过化学和酶促方法，鉴定了大肠杆菌RNA聚合酶与携带lac UV 5启动子的线性DNA片段之间的两种稳定复合物。在这些二元复合物中，DNA可以采用两种交替构象作为温度的函数。用胰腺DNA酶I探测发现，RNA聚合酶和DNA磷酸骨架之间的接触在这两种形式中是不可区分的。然而，保护碱对（CH3）2SO4的反应性的增强仅以在22 ℃以上RPo占优势的形式发生。在低温下稳定的形式，RPi，是一个“封闭”的复合物，因为没有单链区域在DNA中是可检测的。平衡常数的强温度依赖性、转变的中点值和这两种形式之间的转化率与通过使用转录测定进行的一系列测量结果密切一致，并在先前的论文[布克，H.，&麦克卢尔，W. R.（1985）生物化学（在此问题上的前一篇论文）]。这些数据进一步支持开放复合物形成的假设机制，包括三个连续的步骤：R + P在平衡RPc在平衡RPi在平衡RPo。二元复合物RPc在异构化导致开放复合物形成之前在37 ° C下瞬时积累，没有显著地保护其免受酶促裂解或化学修饰，因此与RPi和RPo不同。（250字处删节）
By chemical and enzymatic methods, two stable complexes between Escherichia coli RNA polymerase and a linear DNA fragment carrying the lac UV5 promoter have been identified. In these binary complexes, DNA can adopt two alternate conformations as a function of temperature. Contacts between RNA polymerase and the DNA phosphate backbone are indistinguishable in these two forms, as revealed by probing with pancreatic DNase I. Protection of enhancement of the reactivity of the bases toward (CH3)2SO4 occurs, however, only in the form that predominates above 22 degrees C, RPo. The form stable at low temperature, RPi, is a "closed" complex since no single-stranded region is detectable in the DNA. The strong temperature dependence of the equilibrium constant, the midpoint value of the transition, and the rate of conversion between these two forms are in close agreement with a series of measurements performed by using a transcriptional assay and reported in the preceding paper [Buc, H., & McClure, W. R. (1985) Biochemistry (preceding paper in this issue)]. These data further support the postulated mechanism of open complex formation involving three sequential steps: R + P in equilibrium RPc in equilibrium RPi in equilibrium RPo. The binary complex RPc, which accumulates transiently at 37 degrees C before the isomerization leading to open complex formation, is not significantly protected against enzymatic cleavage or chemical modification and is therefore distinct from RPi and RPo.(ABSTRACT TRUNCATED AT 250 WORDS)
lac ps 启动子中的间隔突变。
DOI：
10.1073/pnas.79.4.1069
发表时间：
1982
影响因子：
11.1
作者：
Stefano,JE;Gralla,JD
通讯作者：
Gralla,JD
影响因子：
5.6
作者：
MALAN, TP;KOLB, A;MCCLURE, WR
通讯作者：
MCCLURE, WR