Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, Japan.
PLoS One. 2013 Jul 10;8(7):e66710. doi: 10.1371/journal.pone.0066710. Print 2013.
TdIF1 was originally identified as a protein that directly binds to DNA polymerase TdT. TdIF1 is also thought to function in transcription regulation, because it binds directly to the transcriptional factor TReP-132, and to histone deacetylases HDAC1 and HDAC2. Here we show that TdIF1 recognizes a specific DNA sequence and regulates gene transcription. By constructing TdIF1 mutants, we identify amino acid residues essential for its interaction with DNA. An in vitro DNA selection assay, SELEX, reveals that TdIF1 preferentially binds to the sequence 5'-GNTGCATG-3' following an AT-tract, through its Helix-Turn-Helix and AT-hook motifs. We show that four repeats of this recognition sequence allow TdIF1 to regulate gene transcription in a plasmid-based luciferase reporter assay. We demonstrate that TdIF1 associates with the RAB20 promoter, and RAB20 gene transcription is reduced in TdIF1-knocked-down cells, suggesting that TdIF1 stimulates RAB20 gene transcription.
TdIF1 最初被鉴定为一种可直接与端粒酶 TdT 结合的蛋白质。TdIF1 还被认为在转录调控中发挥作用，因为它可直接与转录因子 TReP-132 以及组蛋白去乙酰化酶 HDAC1 和 HDAC2 结合。在这里，我们表明 TdIF1 可识别特定的 DNA 序列并调节基因转录。通过构建 TdIF1 突变体，我们确定了其与 DNA 相互作用所必需的氨基酸残基。体外 DNA 选择试验 SELEX 表明，通过其螺旋-转角-螺旋和 AT 钩结构域，TdIF1 优先结合富含 AT 序列的 5'-GNTGCATG-3'。我们表明，该识别序列的四个重复允许 TdIF1 在基于质粒的荧光素酶报告基因检测中调节基因转录。我们证明 TdIF1 与 RAB20 启动子相关联，并且在 TdIF1 敲低的细胞中 RAB20 基因转录减少，表明 TdIF1 可刺激 RAB20 基因转录。
