Functions of protosilencers in the formation and maintenance of heterochromatin in Saccharomyces cerevisiae.
Functions of protosilencers in the formation and maintenance of heterochromatin in Saccharomyces cerevisiae.
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DOI：
10.1371/journal.pone.0037092
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Bi X
中科院分区：
文献类型：
--
作者：
Zhang X;Yu Q;Olsen L;Bi X
在酿酒酵母中，HML和HMR基因座处的转录沉默异染色质是通过募集SIR复合物并促进其沿染色质沿着增殖的沉默子建立的。沉默子由两个或三个结合位点的各种组合组成，这些结合位点用于起始识别复合物（ORC）、Abf 1和Rap 1。单个ORC、Abf 1或Rap 1位点不能促进沉默，但可以通过远距离沉默物增强沉默，并且被称为原型沉默物。原沉默子功能的机制尚不清楚。我们研究的功能ORC，Abf 1和Rap 1网站的组成部分的HMR-E沉默，并作为protosilencers。我们发现，Rap 1网站作出了更大的和独特的贡献HMR-E功能相比，ORC和Abf 1网站。另一方面，Rap 1位点不作为一个protosilator，以帮助HML-E沉默形成异染色质，而ORC和Abf 1位点。因此，Rap 1位点作为HMR-E的组成部分和作为原型沉默子的作用可能涉及不同的机制。由ORC或Abf 1位点与HML-E协同形成的异染色质不如由HMR-E和HML-E形成的异染色质稳定，但增加Abf 1位点的拷贝数增强异染色质稳定性。ORC和Abf 1网站作为protosilencers不调节染色质结构的SIR复合物的情况下，这反对的假设，protosilencers服务于创建一个染色质结构有利于SIR复合物的传播。我们还研究了含有ORC位点和Abf 1位点的ARS 1作为原沉默子的功能。我们发现，ARS 1插入在HML增强异染色质的稳定性，并促进从头形成的染色质结构，部分类似于异染色质在S期依赖的方式。两者合计，我们的研究结果表明，protosilencers援助异染色质结构的形成和维持。
In Saccharomyces cerevisiae, transcriptionally silent heterochromatin at HML and HMR loci is established by silencers that recruit SIR complex and promote its propagation along chromatin. Silencers consist of various combinations of two or three binding sites for origin recognition complex (ORC), Abf1 and Rap1. A single ORC, Abf1 or Rap1 site cannot promote silencing, but can enhance silencing by a distant silencer, and is called a protosilencer. The mechanism of protosilencer function is not known. We examine the functions of ORC, Abf1 and Rap1 sites as components of the HMR-E silencer, and as protosilencers. We find that the Rap1 site makes a larger and unique contribution to HMR-E function compared to ORC and Abf1 sites. On the other hand, Rap1 site does not act as a protosilencer to assist HML-E silencer in forming heterochromatin, whereas ORC and Abf1 sites do. Therefore, different mechanisms may be involved in the roles of Rap1 site as a component of HMR-E and as a protosilencer. Heterochromatin formed by ORC or Abf1 site in collaboration with HML-E is not as stable as that formed by HMR-E and HML-E, but increasing the copy number of Abf1 site enhances heterochromatin stability. ORC and Abf1 sites acting as protosilencers do not modulate chromatin structure in the absence of SIR complex, which argues against the hypothesis that protosilencers serve to create a chromatin structure favorable for SIR complex propagation. We also investigate the function of ARS1 containing an ORC site and an Abf1 site as a protosilencer. We find that ARS1 inserted at HML enhances heterochromatin stability, and promotes de novo formation of a chromatin structure that partially resembles heterochromatin in an S phase dependent manner. Taken together, our results indicate that protosilencers aid in the formation and maintenance of heterochromatin structure.
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影响因子：
10.5
作者：
Maillet, L;Boscheron, C;Gasser, SM
通讯作者：
Gasser, SM
影响因子：
64.5
作者：
Liou, GG;Tanny, JC;Moazed, D
通讯作者：
Moazed, D
影响因子：
11.4
作者：
Boscheron, C;Maillet, L;Gilson, E
通讯作者：
Gilson, E
DOI：
10.1073/pnas.95.10.5521
发表时间：
1998-05-12
影响因子：
11.1
作者：
Cheng, TH;Li, YC;Gartenberg, MR
通讯作者：
Gartenberg, MR
影响因子：
4.8
作者：
Carmen, AA;Milne, L;Grunstein, M
通讯作者：
Grunstein, M