Dipartimento di Biologia e Biotecnologie, "Sapienza" Università di Roma, Italy.
Biophys Chem. 2010 Dec;153(1):43-53. doi: 10.1016/j.bpc.2010.10.003. Epub 2010 Oct 13.
hTERT core promoter regulates telomerase transcription in human cells, thus its structural features are of large interest. We have found that the G-rich hTERT core promoter region, corresponding to the major DNase I hypersensitive site in chromatin organization, contains nine putative G-quadruplex forming sequences (PQS) and is unfavorable for nucleosome formation. Here we show that four PQS are effectively able to form stable parallel intramolecular G-quadruplexes, using PAGE and CD spectroscopy analysis. The PQS-region, as a whole, appears to be organized in three self-interacting G-quadruplexes, probably giving rise to a helicoidal superstructure, as shown by CD and polymerase stop assay. POL-HPDI drugs, that we previously found useful in selectively stabilizing telomeric G-quadruplex, are able to stabilize both the single intramolecular G-quadruplex and the PQS-region superstructure. The features of their induced CD spectra suggest that POL-HPDIs bind to single G-quadruplexes and to whole PQS-region superstructure, mainly by end-stacking interactions.
端粒酶逆转录酶（hTERT）核心启动子调节人细胞中的端粒酶转录，因此其结构特征具有重要意义。我们发现富含鸟嘌呤的 hTERT 核心启动子区域与染色质组织中的主要 DNA 酶 I 超敏位点相对应，包含九个可能的 G-四链体形成序列（PQS），不利于核小体形成。在这里，我们使用 PAGE 和 CD 光谱分析表明，四个 PQS 能够有效地形成稳定的平行分子内 G-四链体。整个 PQS 区域似乎组织成三个自我相互作用的 G-四链体，可能产生螺旋超结构，如 CD 和聚合酶停止测定所示。我们之前发现对选择性稳定端粒 G-四链体有用的 POL-HPDI 药物能够稳定单个分子内 G-四链体和 PQS 区域超结构。它们诱导的 CD 光谱特征表明，POL-HPDIs 主要通过末端堆积相互作用结合到单个 G-四链体和整个 PQS 区域超结构上。
