Abundance of Ribosomal RNA Gene Copies Maintains Genome Integrity
Abundance of Ribosomal RNA Gene Copies Maintains Genome Integrity
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DOI：
10.1126/science.1179044
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发表时间：
2010-02-05
期刊：
影响因子：
56.9
通讯作者：
Kobayashi, Takehiko
中科院分区：
文献类型：
--
作者：
Ide, Satoru;Miyazaki, Takaaki;Kobayashi, Takehiko
核糖体RNA （rDNA）基因重复序列是所有生物体中发现的必不可少的管家基因。基因扩增系统在染色体上保持大量的串联重复拷贝，每个物种都有特定数量的拷贝。酵母有许多未转录的rDNA拷贝（额外的拷贝），我们发现当它们丢失时，细胞对诱变剂引起的DNA损伤变得敏感。我们发现这种敏感性依赖于rDNA转录活性，而rDNA转录活性会干扰姐妹染色单体rDNA位点之间的内聚。额外的rDNA拷贝促进凝聚蛋白结合和姐妹染色单体内聚，从而促进重组修复。这些结果表明，高浓度的大量转录基因对细胞是有毒的，因此扩增的基因，如rDNA，已经进化。
The ribosomal RNA (rDNA) gene repeats are essential housekeeping genes found in all organisms. A gene amplification system maintains large cluster(s) of tandemly repeated copies in the chromosome, with each species having a specific number of copies. Yeast has many untranscribed rDNA copies (extra copies), and we found that when they are lost, the cells become sensitive to DNA damage induced by mutagens. We show that this sensitivity is dependent on rDNA transcriptional activity, which interferes with cohesion between rDNA loci of sister chromatids. The extra rDNA copies facilitate condensin association and sister-chromatid cohesion, thereby facilitating recombinational repair. These results suggest that high concentrations of heavily transcribed genes are toxic to the cells, and therefore amplified genes, such as rDNA, have evolved.