Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, 1245 Lincoln Drive, Carbondale, IL-62901, USA.
Nucleic Acids Res. 2010 Mar;38(5):1461-77. doi: 10.1093/nar/gkp1147. Epub 2009 Dec 9.
Rad26p, a yeast homologue of human Cockayne syndrome B with an ATPase activity, plays a pivotal role in stimulating DNA repair at the coding sequences of active genes. On the other hand, DNA repair at inactive genes or silent areas of the genome is not regulated by Rad26p. However, how Rad26p recognizes DNA lesions at the actively transcribing genes to facilitate DNA repair is not clearly understood in vivo. Here, we show that Rad26p associates with the coding sequences of genes in a transcription-dependent manner, but independently of DNA lesions induced by 4-nitroquinoline-1-oxide in Saccharomyces cerevisiae. Further, histone H3 lysine 36 methylation that occurs at the active coding sequence stimulates the recruitment of Rad26p. Intriguingly, we find that Rad26p is recruited to the site of DNA lesion in an elongating RNA polymerase II-dependent manner. However, Rad26p does not recognize DNA lesions in the absence of active transcription. Together, these results provide an important insight as to how Rad26p is delivered to the damage sites at the active, but not inactive, genes to stimulate repair in vivo, shedding much light on the early steps of transcription-coupled repair in living eukaryotic cells.
Rad26p 是一种酵母同源物，与人类 Cockayne 综合征 B 具有 ATP 酶活性，在刺激活跃基因的编码序列的 DNA 修复中发挥关键作用。另一方面，Rad26p 不调节非活跃基因或基因组的沉默区域的 DNA 修复。然而，Rad26p 如何识别活跃转录基因中的 DNA 损伤以促进 DNA 修复，在体内还不清楚。在这里，我们表明 Rad26p 以转录依赖性的方式与基因的编码序列相关联，但不依赖于 Saccharomyces cerevisiae 中 4-硝基喹啉-1-氧化物诱导的 DNA 损伤。此外，发生在活跃编码序列上的组蛋白 H3 赖氨酸 36 甲基化刺激 Rad26p 的募集。有趣的是，我们发现 Rad26p 以依赖延伸 RNA 聚合酶 II 的方式被募集到 DNA 损伤部位。然而，在没有活跃转录的情况下，Rad26p 不会识别 DNA 损伤。总之，这些结果提供了一个重要的见解，即 Rad26p 如何被递送到活跃但非非活跃基因的损伤部位，以刺激体内修复，为活真核细胞中转录偶联修复的早期步骤提供了重要线索。
