RNA polymerase unwinds an 11-base pair segment of a phage T7 promoter
RNA polymerase unwinds an 11-base pair segment of a phage T7 promoter
复制标题
RNA 聚合酶解开噬菌体 T7 启动子的 11 个碱基对片段
作者：
U. Siebenlist
当RNA聚合酶与启动子位点结合时，它必须解开DNA双螺旋的一部分，以便暴露模板碱基。Wang等人1、Melanova等人2以及Hsieh和Wang3使用不同的实验技术来测量解旋的程度。他们的估计范围从7（参考文献1）到15（参考文献2）碱基对解绕每个结合的大肠杆菌RNA聚合酶（EC 2.7.7.6）。然而，这些研究并没有确定启动子的哪一部分被熔化。这里描述的一种新技术直接证明解旋，并进一步确定了RNA聚合酶在噬菌体T7的A3启动子中打开的确切区域。该启动子是三个强E.在噬菌体T7的生命周期早期使用的大肠杆菌RNA聚合酶启动子（参考文献4）。
WHEN RNA polymerase binds to a promoter site, it must unwind part of the DNA double helix so as to expose the template bases. Wang et al.1, Melnikova et al.2 and Hsieh and Wang3 have used different experimental techniques to measure the degree of unwinding. Their estimates range from 7 (ref. 1) to 15 (ref. 2) base pairs unwound per bound Escherichia coli RNA polymerase (EC 2.7.7.6). These studies, however, do not establish which part of a promoter is melted out. A new technique described here directly proves unwinding and furthermore identifies the exact region that RNA polymerase opens in the A3 promoter of phage T7. This promoter is one of three strong E. coli RNA polymerase promoters used early in the life cycle of phage T7 (ref. 4).