RNA polymerase I transcription obstructs condensin association with 35S rRNA coding regions and can cause contraction of long repeat in Saccharomyces cerevisiae
RNA polymerase I transcription obstructs condensin association with 35S rRNA coding regions and can cause contraction of long repeat in Saccharomyces cerevisiae
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DOI：
10.1111/j.1365-2443.2007.01085.x
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发表时间：
2007-06-01
期刊：
影响因子：
2.1
通讯作者：
Horiuchi, Takashi
中科院分区：
文献类型：
--
作者：
Johzuka, Katsuki;Horiuchi, Takashi
在许多真核细胞中，核糖体RNA基因（rDNA）由高度重复的结构组成。在此之前，我们报道了分离的酿酒酵母的凝聚素突变体是有缺陷的，在携带长rDNA重复由于复制叉屏障（RFB）蛋白Fob1p的损失，从而在突变体中的重复显着收缩。FOB1基因的重新引入抑制了重复序列的收缩。结果发现，凝聚素主要定位在RFB网站在FOB1依赖的方式。在这里，我们表明，RNA聚合酶I转录干扰凝聚素协会与35S rRNA编码区在fob1细胞，并导致显着收缩的rDNA重复在fob1凝聚素双突变体。RNA聚合酶I的失活抑制了fob1凝聚素双突变体中rDNA重复序列的急剧收缩。这些结果表明，凝聚素与RFB位点以外的活性转录区域的协会避免了rDNA重复序列的显着收缩。我们还发现，刺激核糖体DNA重复序列内的RNA聚合酶II转录减少了与活跃转录区域的缩合素关联。因此，凝聚素的一个特征是它与染色质的结合受到转录的干扰。
In many eukaryotic cells, the ribosomal RNA gene (rDNA) is composed of a highly repetitive structure. Previously, we reported the isolation of condensin mutants of Saccharomyces cerevisiae that were defective in carrying long rDNA repeat due to the loss of the replication fork barrier (RFB) protein Fob1p; thus the repeat in the mutants were dramatically contracted. The reintroduction of the FOB1 gene suppressed the contraction of the repeat. It was found that condensin mainly localized at the RFB site in a FOB1-dependent fashion. Here, we show that RNA polymerase I transcription interferes with condensin association with 35S rRNA coding regions in fob1 cells and causes dramatic contraction of rDNA repeat in the fob1 condensin double mutant. Inactivation of RNA polymerase I suppresses the dramatic contraction of the rDNA repeat in the fob1 condensin double mutant. These results suggest that association of condensin with the RFB site outside the active transcription region avoids the dramatic contraction of the rDNA repeat. We also found that the stimulation of RNA polymerase II transcription within the rDNA repeat decreased condensin association with actively transcribed regions. Thus, a characteristic of condensin is that its association with the chromatin is interfered by transcription.