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首页> 外文期刊>Molecular and Cellular Biology >c-Fos-induced activation of a TATA-box-containing promoter involves direct contact with TATA-box-binding protein.
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c-Fos-induced activation of a TATA-box-containing promoter involves direct contact with TATA-box-binding protein.

机译：c-Fos诱导的包含TATA-box的启动子的激活涉及与TATA-box-结合蛋白的直接接触。

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Transcriptional activation in eukaryotes involves protein-protein interactions between regulatory transcription factors and components of the basal transcription machinery. Here we show that c-Fos, but not a related protein, Fra-1, can bind the TATA-box-binding protein (TBP) both in vitro and in vivo and that c-Fos can also interact with the transcription factor IID complex. High-affinity binding to TBP requires c-Fos activation modules which cooperate to activate transcription. One of these activation modules contains a TBP-binding motif (TBM) which was identified through its homology to TBP-binding viral activators. This motif is required for transcriptional activation, as well as TBP binding. Domain swap experiments indicate that a domain containing the TBM can confer TBP binding on Fra-1 both in vitro and in vivo. In vivo activation experiments indicate that a GAL4-Fos fusion can activate a promoter bearing a GAL4 site linked to a TATA box but that this activity does not occur at high concentrations of GAL4-Fos. This inhibition (squelching) of c-Fos activity is relieved by the presence of excess TBP, indicating that TBP is a direct functional target of c-Fos. Removing the TBM from c-Fos severely abrogates activation of a promoter containing a TATA box but does not affect activation of a promoter driven only by an initiator element. Collectively, these results suggest that c-Fos is able to activate via two distinct mechanisms, only one of which requires contact with TBP. Since TBP binding is not exhibited by Fra-1, TBP-mediated activation may be one characteristic that discriminates the function of Fos-related proteins.
机译：真核生物中的转录激活涉及调节转录因子和基础转录机制的组成部分之间的蛋白质-蛋白质相互作用。在这里，我们显示c-Fos，但不是相关蛋白Fra-1，可以在体内和体外结合TATA-box-binding protein（TBP），并且c-Fos也可以与转录因子IID复合体相互作用。与TBP的高亲和力结合需要c-Fos激活模块来协同激活转录。这些激活模块之一包含TBP结合基序（TBM），该基序是通过与TBP结合病毒激活剂的同源性鉴定的。该基序是转录激活以及TBP结合所必需的。结构域交换实验表明，含有TBM的结构域可在体外和体内赋予TBP与Fra-1的结合。体内激活实验表明，GAL4-Fos融合体可以激活带有连接到TATA盒的GAL4位点的启动子，但这种活性在高浓度的GAL4-Fos中不会发生。过量的TBP的存在减轻了对c-Fos活性的抑制（挤压），这表明TBP是c-Fos的直接功能靶标。从c-Fos中除去TBM会严重废除含有TATA盒的启动子的激活，但不会影响仅由引发剂元件驱动的启动子的激活。总的来说，这些结果表明c-Fos能够通过两种不同的机制激活，其中只有一种需要与TBP接触。由于Fra-1没有表现出TBP结合，因此TBP介导的激活可能是区分Fos相关蛋白功能的特征之一。

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