Sgf73, a subunit of SAGA complex, is required for the assembly of RITS complex in fission yeast.
Sgf73, a subunit of SAGA complex, is required for the assembly of RITS complex in fission yeast.
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Sgf73 是 SAGA 复合体的一个亚基，是裂殖酵母中 RITS 复合体组装所必需的
DOI：
10.1038/srep14707
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发表时间：
2015-10-07
影响因子：
4.6
通讯作者：
Lu H
中科院分区：
文献类型：
--
作者：
Deng X;Zhou H;Zhang G;Wang W;Mao L;Zhou X;Yu Y;Lu H
RNA干扰（RNAi）是一种广泛存在的基因沉默机制，是多种生物中异染色质组装所必需的。由Ago1、Tas3和Chp1组成的RNA诱导转录沉默复合体（RITS）是分裂酵母中连接短干扰RNA （siRNA）和异染色质形成的RNAi机制的关键组成部分。然而，RITS的组装过程还没有得到很好的理解。在这里，我们发现Sgf73， SAGA共转录复合体的一个亚基，是中心周围异染色质沉默和siRNA产生所必需的。Sgf73的这种新作用不依赖于SAGA的酶活性或结构完整性。相反，Sgf73在物理上与Ago1和Chp1相关。RITS亚基之间的相互作用，包括Tas3与Chp1之间、Chp1与Ago1之间、Ago1与Tas3之间的相互作用，都因sgf73+的缺失而受损。与此一致的是，在sgf73Δ细胞中，Ago1和Chp1向中心周围区域的募集被取消。我们的研究揭示了SAGA亚基的兼职功能。这表明Sgf73是一个促进RITS组装和rnai介导的异染色质形成的新因子。
RNA interference (RNAi) is a widespread gene-silencing mechanism and is required for heterochromatin assembly in a variety of organisms. The RNA-induced transcriptional silencing complex (RITS), composed of Ago1, Tas3 and Chp1, is a key component of RNAi machinery in fission yeast that connects short interference RNA (siRNA) and heterochromatin formation. However, the process by which RITS is assembled is not well understood. Here, we identified Sgf73, a subunit of the SAGA co-transcriptional complex, is required for pericentromeric heterochromatin silencing and the generation of siRNA. This novel role of Sgf73 is independent of enzymatic activities or structural integrity of SAGA. Instead, Sgf73 is physically associated with Ago1 and Chp1. The interactions among the subunits of the RITS, including those between Tas3 and Chp1, between Chp1 and Ago1, between Ago1 and Tas3, were all impaired by the deletion of sgf73+. Consistently, the recruitment of Ago1 and Chp1 to the pericentromeric region was abolished in sgf73Δ cells. Our study unveils a moonlighting function of a SAGA subunit. It suggests Sgf73 is a novel factor that promotes assembly of RITS and RNAi-mediated heterochromatin formation.