Yeast Rpb9 plays an important role in ubiquitylation and degradation of Rpb1 in response to UV-induced DNA damage
Yeast Rpb9 plays an important role in ubiquitylation and degradation of Rpb1 in response to UV-induced DNA damage
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DOI：
10.1128/mcb.00404-07
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发表时间：
2007-07-01
影响因子：
5.3
通讯作者：
Li, Shisheng
中科院分区：
文献类型：
--
作者：
Chen, Xuefeng;Ruggiero, Christine;Li, Shisheng
Rpb 9是RNA聚合酶II（Pol II）的非必需亚基，在酿酒酵母中具有多种转录相关功能，包括转录延伸和转录偶联修复（TCR）。在这里，我们表明，在响应紫外线辐射，Rpb 9也在促进泛素化和降解的Rpbl，Pol II的最大亚基的功能。Rpb 9的这种功能不受任何核苷酸切除修复途径的影响，包括Rpb 9本身和Rad 26介导的TCR。Rpb 9由三个不同的结构域组成：N-末端Zn 1，C-末端Zn 2和中心连接体。Zn 2结构域是Rpb 9促进Rpbl降解所必需的，其对于转录延伸和TCR功能是必需的，而Zn 1和接头结构域对于转录延伸和TCR功能是必需的，其在Rpbl降解中起辅助作用。免疫共沉淀分析表明，几乎全长的Rpb 9是需要一个强大的相互作用与核心Pol II：删除的Zn 2结构域导致显着减弱的相互作用，而删除的Zn 1和接头导致无法检测到的相互作用。此外，我们表明，Rpbl，而不是整个Pol II复合物，降解响应UV辐射，降解主要是由26 S蛋白酶体介导的。
Rpb9, a nonessential subunit of RNA polymerase II (Pol II), has multiple transcription-related functions in Saccharomyces cerevisiae, including transcription elongation and transcription-coupled repair (TCR). Here we show that, in response to UV radiation, Rpb9 also functions in promoting ubiquitylation and degradation of Rpbl, the largest subunit of Pol II. This function of Rpb9 is not affected by any pathways of nucleotide excision repair, including TCR mediated by Rpb9 itself and by Rad26. Rpb9 is composed of three distinct domains: the N-terminal Zn1, the C-terminal Zn2, and the central linker. The Zn2 domain, which is dispensable for transcription elongation and TCR functions, is essential for Rpb9 to promote Rpbl degradation, whereas the Zn1 and linker domains, which are essential for transcription elongation and TCR functions, play a subsidiary role in Rpbl degradation. Coimmunoprecipitation analysis suggests that almost the full length of Rpb9 is required for a strong interaction with the core Pol II: deletion of the Zn2 domain causes dramatically weakened interaction, whereas deletion of Zn1 and the linker resulted in undetectable interaction. Furthermore, we show that Rpbl, rather than the whole Pol II complex, is degraded in response to UV radiation and that the degradation is primarily mediated by the 26S proteasome.