论文信息 - 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

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).

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