SIR2 and SIR4 interactions differ in core and extended telomeric heterochromatin in yeast
SIR2 and SIR4 interactions differ in core and extended telomeric heterochromatin in yeast
复制标题
DOI：
10.1101/gad.11.1.83
复制
发表时间：
1997-01-01
影响因子：
10.5
通讯作者：
Grunstein, M
中科院分区：
文献类型：
--
作者：
StrahlBolsinger, S;Hecht, A;Grunstein, M
酵母核心端粒异染色质可以沉默相邻的基因，并需要RAP 1，SIR2，SIR3和SIR4以及组蛋白H3和H4来实现这种端粒位置效应。SIR3的过量产生可以延长沉默结构域。我们在这里研究这些多蛋白复合物的性质。从全细胞提取物中免疫沉淀SIR2和SIR4。此外，使用甲醛交联，我们绘制了SIR2，SIR4和RAP 1沿着端粒染色质在SIR3过表达前后。我们的数据表明，SIR2和SIR4在蛋白质复合物中相互作用，并且SIR2、SIR3、SIR4和RAP 1在野生型细胞中沿着沿着端粒异染色质映射到相同的位点。然而，当过表达时，SIR3沿着染色体扩散，并且其相互作用对SIR4，特别是SIR2的相互作用是显性的，SIR2的检测在延伸的异染色质中降低。RAP 1在核心区域的结合不受SIR3过度产生的影响，并且RAP 1没有显示出扩散的证据。因此，我们建议，核心端粒异染色质的结构不同于由SIR3扩展。
Yeast core telomeric heterochromatin can silence adjacent genes and requires RAP1, SIR2, SIR3, and SIR4 and histones H3 and H4 for this telomere position effect. SIR3 overproduction can extend the silenced domain. We examine here the nature of these multiprotein complexes. SIR2 and SIR4 were immunoprecipitated from whole-cell extracts. In addition, using formaldehyde cross-linking we have mapped SIR2, SIR4, and RAP1 along telomeric chromatin before and after SIR3 overexpression. Our data demonstrate that SIR2 and SIR4 interact in a protein complex and that SIR2, SIR3, SIR4 and RAP1 map to the same sites along telomeric heterochromatin in wild-type cells. However, when overexpressed, SIR3 spreads along the chromosome and its interactions are dominant to those of SIR4 and especially SIR2, whose detection is decreased in extended heterochromatin. RAP1 binding at the core region is unaffected by SIR3 overproduction and RAP1 shows no evidence of spreading. Thus, we propose that the structure of core telomeric heterochromatin differs from that extended by SIR3.