Evidence for Multiple Mediator Complexes in Yeast Independently Recruited by Activated Heat Shock Factor
Evidence for Multiple Mediator Complexes in Yeast Independently Recruited by Activated Heat Shock Factor
复制标题
DOI：
10.1128/mcb.00005-16
复制
发表时间：
2016-07-01
影响因子：
5.3
通讯作者：
Gross, David S.
中科院分区：
文献类型：
--
作者：
Anandhakumar, Jayamani;Moustafa, Yara W.;Gross, David S.
中介体是一种进化上保守的RNA聚合酶II转录必需的共激活因子复合体。虽然一般认为在酿酒酵母中，Mediator是一种稳定的三模复合物，但其在体内的结构状态尚不清楚。利用“锚移”（AA）技术有条件地耗尽Mediator及其可逆相关Cdk8激酶模块（CKM）中的选择亚基，我们提供了证据，证明Mediator的尾部模块是高度动态的，并且由Med2、Med3和Med15组成的亚复合物可以独立地招募到热休克因子1 （Hsf1）激活基因的调控区域。一个支架亚基（Med14）锚定菌株的荧光显微镜证实了位于尾部三联体外的核心亚基的平行细胞质隔离。此外，与目前的模型相反，我们提供的证据表明Hsf1可以独立于核心中介招募CKM，核心中介在调节起始后事件中发挥作用。总的来说，我们的结果表明酵母介质不是单一的，但潜在的动态复杂性，迄今未被认识到。在AA菌株中，包括CKM- mediator、21亚基核心复合物、Med2-Med3-Med15尾三联体和4亚基CKM在内的多个物种可以被激活的Hsf1独立募集到其靶基因上。
Mediator is an evolutionarily conserved coactivator complex essential for RNA polymerase II transcription. Although it has been generally assumed that in Saccharomyces cerevisiae, Mediator is a stable trimodular complex, its structural state in vivo remains unclear. Using the "anchor away" (AA) technique to conditionally deplete select subunits within Mediator and its reversibly associated Cdk8 kinase module (CKM), we provide evidence that Mediator's tail module is highly dynamic and that a subcomplex consisting of Med2, Med3, and Med15 can be independently recruited to the regulatory regions of heat shock factor 1 (Hsf1)-activated genes. Fluorescence microscopy of a scaffold subunit (Med14)-anchored strain confirmed parallel cytoplasmic sequestration of core subunits located outside the tail triad. In addition, and contrary to current models, we provide evidence that Hsf1 can recruit the CKM independently of core Mediator and that core Mediator has a role in regulating postinitiation events. Collectively, our results suggest that yeast Mediator is not monolithic but potentially has a dynamic complexity heretofore unappreciated. Multiple species, including CKM-Mediator, the 21-subunit core complex, the Med2-Med3-Med15 tail triad, and the four-subunit CKM, can be independently recruited by activated Hsf1 to its target genes in AA strains.