General transcription factors and core promoter elements play a pivotal role in RNA polymerase II (Pol II)-mediated transcription initiation. In the previous work, we have defined a TFIIA recognition element (IIARE) that modulates Pol II-directed gene transcription in a promoter context-dependent manner. However, how TFIIA interacts with the IIARE and whether the interaction between TFIIA and the IIARE is involved in the regulation of gene transcription by Pol II are not fully understood. In the present study, we confirm that both K348 and K350 residues in TFIIAαβ are required for the interaction between TFIIAαβ and the IIARE. Disruption of the interaction between them by gene mutations dampens TFIIAαβ binding to the AdML-IIARE promoter and the transcriptional activation of the promoter containing a IIARE in vitro and in vivo. Stable expression of the TFIIAαβ mutant containing both K348A and K350A in the cell line with endogenous TFIIAαβ silence represses endogenous gene expression by reducing the occupancies of TFIIAαβ, TBP, p300, and Pol II at the promoters containing a IIARE. The findings from this study provide a novel insight into the regulatory mechanism of gene transcription mediated by TFIIA and the IIARE.

通用转录因子和核心启动子元件在RNA聚合酶II（Pol II）介导的转录起始中起关键作用。在之前的工作中，我们定义了一个TFIIA识别元件（IIARE），该元件以启动子上下文相关的方式调节Pol II定向的基因转录。然而，尚未完全了解TFIIA如何与IIARE相互作用以及TFIIA与IIARE之间的相互作用是否参与了Pol II对基因转录的调控。在本研究中，我们确认TFIIAαβ中的K348和K350残基都是TFIIAαβ和IIARE之间相互作用的必需条件。基因突变破坏它们之间的相互作用会削弱TFIIAαβ与AdML-IIARE启动子的结合以及体外含IIARE的启动子的转录激活和体内。内源性TFIIAαβ沉默的细胞系中同时含有K348A和K350A的TFIIAαβ突变体的稳定表达通过减少TIFIAαβ，TBP，p300和Pol II在含有IIARE的启动子上的占有率来抑制内源基因表达。这项研究的发现为TFIIA和IIARE介导的基因转录调控机制提供了新颖的见解。