Nath S T, Lee M S, Romano L J
Nucleic Acids Res. 1987 May 26;15(10):4257-71. doi: 10.1093/nar/15.10.4257.
The effect of modifying the T7 promoter-containing plasmid pDR100 with aminofluorene (AF), acetylaminofluorene (AAF), and benzo[a]pyrene (B[a]P) adducts on RNA synthesis by the T7 RNA polymerase was determined. We found that increasing levels of each of the three adducts caused a progressive decline in RNA synthesis, but that the inhibition produced by benzo[a]pyrene adducts was substantially greater than that caused by either AF or AAF adducts. Polyacrylamide gel electrophoresis analysis confirmed that the B[a]P adducts more strongly inhibited chain elongation since their presence resulted in the production of RNA fragments having average chain lengths very close to that predicted if each adduct permanently blocked the polymerase during transcription. We have also determined the effect of each type of adduct on the initiation of transcription and show that the T7 RNA polymerase initiates as efficiently on both AF or AAF-containing templates as it does on unmodified DNA, while B[a]P adducts were found to increase in the number of chain starts.
测定了用氨基芴（AF）、乙酰氨基芴（AAF）和苯并[a]芘（B[a]P）加合物修饰含T7启动子的质粒pDR100对T7 RNA聚合酶RNA合成的影响。我们发现，三种加合物中每一种加合物水平的增加都会导致RNA合成逐渐下降，但苯并[a]芘加合物产生的抑制作用明显大于AF或AAF加合物所引起的抑制作用。聚丙烯酰胺凝胶电泳分析证实，B[a]P加合物对链延伸的抑制作用更强，因为它们的存在导致产生的RNA片段的平均链长非常接近如果每个加合物在转录过程中永久阻断聚合酶时所预测的链长。我们还确定了每种加合物对转录起始的影响，并表明T7 RNA聚合酶在含AF或AAF的模板上起始转录的效率与在未修饰的DNA上一样高，而发现B[a]P加合物会增加链起始的数量。
