Guanine repeat-containing sequences confer transcription-dependent instability in an orientation-specific manner in yeast.
Guanine repeat-containing sequences confer transcription-dependent instability in an orientation-specific manner in yeast.
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DOI：
10.1016/j.dnarep.2011.07.002
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发表时间：
2011-09-05
期刊：
影响因子：
3.8
通讯作者：
Jinks-Robertson S
中科院分区：
文献类型：
--
作者：
Kim N;Jinks-Robertson S
非B DNA结构是与重复序列相关的基因组不稳定性的主要贡献者。免疫球蛋白开关Mu（Sμ）区序列由富含鸟嘌呤的重复序列组成，具有形成G4 DNA的高潜力，其中一条DNA链折叠成鸟嘌呤四联体阵列。利用酿酒酵母的遗传可塑性，我们开发了一种重组试验，以研究参与维持富含G重复序列的稳定性的机制。通过将Sμ序列嵌入四环素调控的启动子调控的重组底物中，我们证明了转录的速率和方向都影响Sμ序列的稳定性。特别是，在高转录条件下，当Sμ序列以富含C的链作为转录模板时，观察到最大的不稳定性。在缺乏IB型拓扑异构酶Top1的情况下，转录方向的作用增强，这可能是由于增强的R环形成。Sgs1解旋酶和RNase H活性的丧失也增加了不稳定性，这表明它们可能协同作用以减少高度转录区域中非B DNA结构的形成。最后，Sμ序列是不稳定的，当转录延伸受到干扰，由于一个缺陷的THO复合物。在TH缺陷的背景下，与异位表达的单链胞嘧啶脱氨酶AID相关的方向依赖性不稳定性进一步恶化。我们的研究结果的影响，了解潜在的G4 DNA形成序列的不稳定性进行了讨论。
Non-B DNA structures are a major contributor to the genomic instability associated with repetitive sequences. Immunoglobulin switch Mu (Sμ) region sequence is comprised of guanine-rich repeats and has high potential for forming G4 DNA, in which one strand of DNA folds into an array of guanine quartets. Taking advantage of the genetic tractability of Saccharomyces cerevisiae, we developed a recombination assay to investigate mechanisms involved in maintaining stability of G-rich repetitive sequence. By embedding Sμ sequence within recombination substrates under the control of a tetracycline-regulatable promoter, we demonstrate that the rate and orientation of transcription both affect the stability of Sμ sequence. In particular, the greatest instability was observed under high-transcription conditions when the Sμ sequence was oriented with the C-rich strand as the transcription template. The effect of transcription orientation was enhanced in the absence of the Type IB topoiosmerase Top1, possibly due to enhanced R-loop formation. Loss of Sgs1 helicase and RNase H activity also increased instability, suggesting they may cooperatively function to reduce the formation of non-B DNA structures in highly transcribed regions. Finally, the Sμ sequence was unstable when transcription elongation was perturbed due to a defective THO complex. In a THO-deficient background, there was further exacerbation of orientation-dependent instability associated with the ectopically expressed, single-strand cytosine deaminase AID. The implications of our findings to understanding instability associated with potential G4 DNA forming sequences are discussed.
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影响因子：
10.5
作者：
Duquette, ML;Handa, P;Maizels, N
通讯作者：
Maizels, N
影响因子：
3.8
作者：
Kim, Nayun;Abdulovic, Amy L.;Jinks-Robertson, Sue
通讯作者：
Jinks-Robertson, Sue
影响因子：
5.3
作者：
French, Sarah L.;Sikes, Martha L.;Beyer, Ann L.
通讯作者：
Beyer, Ann L.
DOI：
10.1073/pnas.92.8.3526
发表时间：
1995-04-11
影响因子：
11.1
作者：
DROLET, M;PHOENIX, P;CROUCH, RJ
通讯作者：
CROUCH, RJ
影响因子：
16
作者：
Huertas, P;Aguilera, A
通讯作者：
Aguilera, A