CNRS UMR 7196, Muséum National d'Histoire Naturelle, INSERM U 565, Case Postale 26, 43 rue Cuvier, Cedex 05, 75005 Paris, France.
Nucleic Acids Res. 2010 Mar;38(5):e31. doi: 10.1093/nar/gkp1139. Epub 2009 Dec 8.
A SELEX approach has been developed in order to select oligonucleotides that bind double-stranded DNA in the presence of a triplex-stabilizing agent, and was applied to a target sequence containing an oligopurine-oligopyrimidine stretch. After only seven rounds of selection, the process led to the identification of oligonucleotides that were able to form triple helices within the antiparallel motif. Inspection of the selected sequences revealed that, contrary to GC base pair which were always recognized by guanines, recognition of AT base pair could be achieved by either adenine or thymine, depending on the sequence context. While thymines are strongly preferred for several positions, some others can accommodate the presence of adenines. These results contribute to set the rules for designing oligonucleotides that form stable triple helices in the presence of triplex-stabilizing agents at physiological pH. They set the basis for further experiments regarding extension of potential target sequences for triple-helix formation or recognition of ligand-DNA complexes.
为了在三链体稳定试剂存在的情况下选择与双链 DNA 结合的寡核苷酸，已经开发了一种 SELEX 方法，并将其应用于含有寡聚嘌呤-寡聚嘧啶延伸的靶序列。经过仅七轮的选择，该过程导致鉴定出能够在反平行基序内形成三螺旋的寡核苷酸。对所选序列的检查表明，与 GC 碱基对始终被鸟嘌呤识别相反，AT 碱基对的识别可以通过腺嘌呤或胸腺嘧啶来实现，这取决于序列上下文。虽然胸腺嘧啶在几个位置上被强烈偏好，但其他一些位置可以容纳腺嘌呤的存在。这些结果有助于制定在生理 pH 值下使用三链体稳定试剂形成稳定三螺旋的寡核苷酸设计规则。它们为进一步的实验奠定了基础，这些实验涉及扩展三螺旋形成的潜在靶序列或识别配体-DNA 复合物。
