Molecular Cancer Research, Netherlands Proteomics Centre, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands.
Nucleic Acids Res. 2012 Feb;40(3):996-1008. doi: 10.1093/nar/gkr784. Epub 2011 Oct 5.
TATA-binding protein (TBP) is central to the regulation of eukaryotic transcription initiation. Recruitment of TBP to target genes can be positively regulated by one of two basal transcription factor complexes: SAGA or TFIID. Negative regulation of TBP promoter association can be performed by Mot1p or the NC2 complex. Recent evidence suggests that Mot1p, NC2 and TBP form a DNA-dependent protein complex. Here, we compare the functions of Mot1p and NC2βduring basal and activated transcription using the anchor-away technique for conditional nuclear depletion. Genome-wide expression analysis indicates that both proteins regulate a highly similar set of genes. Upregulated genes were enriched for SAGA occupancy, while downregulated genes preferred TFIID binding. Mot1p and NC2β depletion during heat shock resulted in failure to downregulate gene expression after initial activation, which was accompanied by increased TBP and RNA pol II promoter occupancies. Depletion of Mot1p or NC2β displayed preferential synthetic lethality with the TBP-interaction module of SAGA. Our results support the model that Mot1p and NC2β directly cooperate in vivo to regulate TBP function, and that they are involved in maintaining basal expression levels as well as in resetting gene expression after induction by stress.
TATA 结合蛋白（TBP）是真核转录起始调控的核心。TBP 与靶基因的募集可以通过两种基本转录因子复合物之一进行正向调节：SAGA 或 TFIID。TBP 启动子结合的负调控可以由 Mot1p 或 NC2 复合物完成。最近的证据表明，Mot1p、NC2 和 TBP 形成一个依赖于 DNA 的蛋白质复合物。在这里，我们使用条件核耗竭的锚定法比较了 Mot1p 和 NC2β 在基础转录和激活转录中的功能。全基因组表达分析表明，这两种蛋白质调节高度相似的一组基因。上调基因富集了 SAGA 占据，而下调基因则偏好 TFIID 结合。热休克期间 Mot1p 和 NC2β 的耗竭导致初始激活后基因表达下调失败，这伴随着 TBP 和 RNA pol II 启动子占据的增加。Mot1p 或 NC2β 的耗竭与 SAGA 的 TBP 相互作用模块表现出优先的合成致死性。我们的结果支持这样一种模型，即 Mot1p 和 NC2β 直接在体内合作调节 TBP 功能，并且它们参与维持基础表达水平以及在应激诱导后重新设置基因表达。
