TRANSCRIPTION-INDUCED CONFORMATIONAL CHANGE IN A TOPOLOGICALLY CLOSED DNA DOMAIN
TRANSCRIPTION-INDUCED CONFORMATIONAL CHANGE IN A TOPOLOGICALLY CLOSED DNA DOMAIN
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DOI：
10.1093/nar/19.11.2941
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发表时间：
1991-06-11
影响因子：
14.9
通讯作者：
NORDHEIM, A
中科院分区：
文献类型：
--
作者：
DROGE, P;NORDHEIM, A
我们已经在体外测试了在一个区域的交替嘌呤和嘧啶作为转录诱导的负超螺旋的结果的B-到-Z转换的发生。 通过使用单克隆抗体作为一个特定的Z-DNA稳定剂，我们证明了左手DNA的形成可以瞬时发生时，一个拓扑不受约束的模板被转录。 在模板亚群中观察到的B到Z转变似乎是由在延长T7 RNA聚合酶之后产生的负超螺旋诱导的。 与此相一致的是，在转录期间拓扑异构酶的存在阻止了DNA构象的变化。 这些数据与Liu和Wang（1）的“双超螺旋结构域”转录模型一致。 有趣的是，我们的研究结果表明，转录诱导的超螺旋扭曲的扩散速率必须相对较慢，与它们的产生相比，在体外条件下，局部的瞬时超螺旋可以达到意想不到的高水平。
We have tested in vitro the occurrence of a B-to-Z transition in a region of alternating purines and pyrimidines as a consequence of transcription-induced negative supercoiling. By using a monoclonal antibody as a specific Z-DNA stabilizing agent, we demonstrate that the formation of left-handed DNA can transiently occur when a topologically unconstrained template is transcribed. The B-to-Z transition, observed in a subpopulation of templates, appears to be induced by negative supercoiling generated in the wake of an elongating T7 RNA polymerase. Consistent with this, the presence of topoisomerases durig the transcription period prevents the change in DNA conformation. These data agree with the 'twin-supercoiled-domain' model for transcription of Liu and Wang (1). Interestingly, our results suggest that the diffusion rate of transcription-induced superhelical twists must be relatively slow compared to their generation, and that under in vitro conditions localized transient supercoiling can reach unexpectedly high levels.