Gottesfeld J M
Nucleic Acids Res. 1986 Mar 11;14(5):2075-88. doi: 10.1093/nar/14.5.2075.
The role of DNA topoisomerases in eucaryotic class III gene transcription in vitro has been studied through the use of inhibitory drugs and antisera to DNA topoisomerases I and II. The DNA topoisomerase II inhibitors, novobiocin and coumermycin AI, were found to inhibit transcription of cloned 5S and tRNA genes. Novobiocin acts by interfering with an ATP-requiring step in the pathway to stable preinitiation complex formation. However, it is unlikely that this step reflects the enzymatic action of DNA topoisomerase II since a specific inhibitor of this enzyme (VM-26) and anti-DNA topoisomerase II antibodies fail to inhibit transcription under conditions where topoisomerase II enzymatic activity is inhibited. Similarly, a specific inhibitor of DNA topoisomerase I (camptothecin) and anti-DNA topoisomerase I antibodies fail to inhibit class III gene transcription. These results argue against a role for either DNA topoisomerase in 5S or tRNA gene transcription in vitro.
通过使用DNA拓扑异构酶I和II的抑制药物及抗血清，研究了DNA拓扑异构酶在真核生物III类基因体外转录中的作用。发现DNA拓扑异构酶II抑制剂新生霉素和香豆霉素AI可抑制克隆的5S和tRNA基因的转录。新生霉素通过干扰稳定的起始前复合物形成途径中一个需要ATP的步骤来发挥作用。然而，这一步骤不太可能反映DNA拓扑异构酶II的酶促作用，因为在该酶的酶活性受到抑制的条件下，该酶的特异性抑制剂（VM - 26）和抗DNA拓扑异构酶II抗体未能抑制转录。同样，DNA拓扑异构酶I的特异性抑制剂（喜树碱）和抗DNA拓扑异构酶I抗体也未能抑制III类基因转录。这些结果表明，在体外5S或tRNA基因转录中，两种DNA拓扑异构酶均不起作用。
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