Guieysse A L, Praseuth D, Francois J C, Helene C
Laboratoire de Biophysique, INSERM U 201-CNRS UA 481, Muséum National d'Histoire Naturelle, Paris, France.
Biochem Biophys Res Commun. 1995 Dec 5;217(1):186-94. doi: 10.1006/bbrc.1995.2762.
Oligonucleotide-directed triple helix formation constitutes a new approach to block gene expression via transcription inhibition. In addition triple helices might inhibit replication. We have examined the capacity of triple helix-forming oligonucleotides to inhibit the initiation of replication on a single-stranded DNA template using T7 DNA polymerase (Sequenase). We show that triple helix formation at the primer initiation site efficiently inhibits DNA polymerization, by preventing binding of the polymerase. The effect is dependent on the distance between the 3'-end of the primer and the triple helix boundary. Inhibition becomes ineffective when this distance is greater than 3 nucleotides. The presence of three base-pairs outside the triple-helical region on the 3'-side of the primer is therefore sufficient to allow for initiation of DNA replication.
寡核苷酸定向三链螺旋形成是一种通过转录抑制来阻断基因表达的新方法。此外，三链螺旋可能会抑制复制。我们使用T7 DNA聚合酶（测序酶）研究了三链螺旋形成寡核苷酸抑制单链DNA模板上复制起始的能力。我们表明，在引物起始位点形成三链螺旋可通过阻止聚合酶结合而有效抑制DNA聚合。这种效应取决于引物3'末端与三链螺旋边界之间的距离。当该距离大于3个核苷酸时，抑制作用失效。因此，引物3'侧三链螺旋区域外存在三个碱基对就足以启动DNA复制。
