Meinhart Anton, Blobel Jascha, Cramer Patrick
Institute of Biochemistry, Gene Center, University of Munich, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
J Biol Chem. 2003 Nov 28;278(48):48267-74. doi: 10.1074/jbc.M307874200. Epub 2003 Sep 17.
Initiation of eukaryotic mRNA transcription requires melting of promoter DNA with the help of the general transcription factors TFIIE and TFIIH. Here we define a conserved and functionally essential N-terminal domain in TFE, the archaeal homolog of the large TFIIE subunit alpha. X-ray crystallography shows that this TFE domain adopts a winged helix-turn-helix (winged helix) fold, extended by specific alpha-helices at the N and C termini. Although the winged helix fold is often found in DNA-binding proteins, we show that TFE is not a typical DNA-binding winged helix protein, because its putative DNA-binding face shows a negatively charged groove and an unusually long wing, and because the domain lacks DNA-binding activity in vitro. The groove and a conserved hydrophobic surface patch on the additional N-terminal alpha-helix may, however, allow for interactions with other general transcription factors and RNA polymerase. Homology modeling shows that the TFE domain is conserved in TFIIE alpha, including the potential functional surfaces.
真核生物mRNA转录的起始需要在通用转录因子TFIIE和TFIIH的帮助下使启动子DNA解链。在此，我们确定了TFE中一个保守且功能必需的N端结构域，TFE是大型TFIIE亚基α的古菌同源物。X射线晶体学表明，该TFE结构域采用了翼状螺旋-转角-螺旋（翼状螺旋）折叠结构，并在N端和C端由特定的α螺旋延伸。尽管翼状螺旋折叠结构常见于DNA结合蛋白中，但我们发现TFE并非典型的DNA结合翼状螺旋蛋白，这是因为其假定的DNA结合面呈现出一个带负电荷的凹槽和一个异常长的侧翼，并且该结构域在体外缺乏DNA结合活性。然而，该凹槽以及额外N端α螺旋上一个保守的疏水表面区域可能允许与其他通用转录因子和RNA聚合酶相互作用。同源建模表明，TFE结构域在TFIIEα中是保守的，包括潜在的功能表面。
