Association of the Winged Helix Motif of the TFIIEα Subunit of TFIIE with Either the TFIIEβ Subunit or TFIIB Distinguishes Its Functions in Transcription.
Association of the Winged Helix Motif of the TFIIEα Subunit of TFIIE with Either the TFIIEβ Subunit or TFIIB Distinguishes Its Functions in Transcription.
复制标题
TFIIE 的 TFIIEα 亚基的翼状螺旋基序与 TFIIEβ 亚基或 TFIIB 的关联可区分其转录功能。
作者：
Tanaka;A.;Akimoto;Y.;Kobayashi;S.;Hisatake;K.;Hanaoka;F.;and Ohkuma;Y.
在真核生物中，通用转录因子TFIIE由α和β两个亚基组成，在转录中起着至关重要的作用。结构-功能研究表明，TFIIE具有三个翼螺旋（WH）基序，其中一个在TFIIEα中，两个在TFIIEβ中。最近的研究表明，通过结合RNA聚合酶II的箝位区，TFIIEα - WH促进了将启动子结合的无活性起始前复合物转化为活性复合物的构象变化。为了阐明其在转录中的作用，我们对点突变的人TFIIEα - WH蛋白进行了功能分析。在体外转录分析中鉴定出两类突变体。一类是转录起始缺陷，另一类是起始到延伸过渡缺陷。对该基序与其他一般转录因子的结合分析表明，前者在与TFIIB β的基本螺旋-环-螺旋基序结合时存在缺陷，后者在与TFIIB的N端周期蛋白同源区结合时存在缺陷。此外，TFIIEα - WH在第三个不同的区域与tfiie XPB亚基结合。因此，这些结果为RNA聚合酶II在转录初始阶段激活的机制提供了进一步的见解。
In eukaryotes, the general transcription factor TFIIE consists of two subunits, α and β, and plays essential roles in transcription. Structure–function studies indicate that TFIIE has three‐winged helix (WH) motifs, with one in TFIIEα and two in TFIIEβ. Recent studies suggested that, by binding to the clamp region of RNA polymerase II, TFIIEα‐WH promotes the conformational change that transforms the promoter‐bound inactive preinitiation complex to the active complex. Here, to elucidate its roles in transcription, functional analyses of point‐mutated human TFIIEα‐WH proteins were carried out.In vitrotranscription analyses identified two classes of mutants. One class was defective in transcription initiation, and the other was defective in the transition from initiation to elongation. Analyses of the binding of this motif to other general transcription factors showed that the former class was defective in binding to the basic helix‐loop‐helix motif of TFIIEβ and the latter class was defective in binding to the N‐terminal cyclin homology region of TFIIB. Furthermore, TFIIEα‐WH bound to the TFIIH XPB subunit at a third distinct region. Therefore, these results provide further insights into the mechanisms underlying RNA polymerase II activation at the initial stages of transcription.