BACKGROUND Human immunodeficiency virus type-1 (HIV-1) infection is the reason for the epidemic of acquired immunodeficiency syndrome (AIDS). Developing HIV-1 fusion inhibitors gained increasing attention as they took effect in the early stage of HIV-1 infecting cells. DNA G-quadruplex-based inhibitors had been found to interact with HIV-1 envelope glycoprotein, showing anti-HIV-1 fusion activity. C-peptide derived molecules with Met-Thr terminal also showed potent anti-fusion activity, the Met-Thr dipeptide adopted a hook-like structure (termed MT hook) in the hydrophobic pocket to "anchor" inhibitors to the N-terminal heptad repeat (NHR) of HIV-1 envelope glycoprotein gp41. OBJECTIVE Our work was to conjugate MT hooks to the 5'-terminal ends of DNA quadruplex-based inhibitor and demonstrate its biophysical characterization and anti-HIV-1 fusion activity. METHODS A 6-aminohexanol phosphonamidite was utilized in solid synthesis for the conjunction of oligodeoxynucleotide and MT dipeptide. Hydrophobic groups were introduced by a nucleoside analogue from the base site. Circular dichroism spectrum and native polyacrylamide gel electrophoresis were used to confirm the helix formation. A cell-cell fusion assay was carried out to test the anti-fusion activity. RESULTS The conjugate G1 showed improved anti-cell-cell fusion activity than quadruplex without MT hook. The MT hook did not affect the oligodeoxynucleotide (ODN) G-quadruplex assembly. It was also proved that G1 could effectively interfere with endogenous 6-helical bundle (6HB) formation between the N-terminal heptad repeat N36 (NHR) and the C-terminal heptad repeat C34 (CHR) during virus fusion course. CONCLUSION In this work, conjugate of DNA-oligopeptide were successfully synthesized. The conjugation of MT hook did improve the anti-fusion activity of DNA G-quadruplex-based inhibitors. Our results can add information regarding on structure-activity relationships of DNA helix-based inhibitors and provide a reference for the follow-up experimental studies.

中文翻译：

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二肽MT钩偶联的DNA四链体基抑制剂的合成，生物物理表征和抗HIV-1融合活性。

背景技术人类免疫缺陷病毒1型（HIV-1）感染是获得性免疫缺陷综合症（AIDS）流行的原因。开发中的HIV-1融合抑制剂在HIV-1感染细胞的早期阶段就发挥了作用，因此受到越来越多的关注。已发现基于DNA G-四链体的抑制剂与HIV-1包膜糖蛋白相互作用，显示出抗HIV-1融合活性。具有Met-Thr末端的C肽衍生分子也显示出强大的抗融合活性，Met-Thr二肽在疏水性口袋中采用了钩状结构（称为MT钩），可将抑制剂“锚定”至N端七肽重复序列HIV-1包膜糖蛋白gp41（NHR）。目的我们的工作是将MT钩子缀合到5' -基于DNA四链体的抑制剂的末端-并显示其生物物理特征和抗HIV-1融合活性。方法采用6-氨基己醇磷酸亚胺用于固相合成寡脱氧核苷酸和MT二肽。通过碱基部位的核苷类似物引入疏水基团。圆二色性光谱和天然聚丙烯酰胺凝胶电泳用于确认螺旋的形成。进行细胞-细胞融合测定以测试抗融合活性。结果与没有MT钩的四链体相比，缀合物G1显示出改善的抗细胞-细胞融合活性。MT钩不影响寡脱氧核苷酸（ODN）G四联体组装。还证明了在病毒融合过程中，G1可以有效干扰N末端七肽重复序列N36（NHR）和C末端七肽重复序列C34（CHR）之间的内源性6螺旋束（6HB）形成。结论在这项工作中，成功地合成了DNA-寡肽的缀合物。MT钩的缀合确实改善了基于DNA G-四链体的抑制剂的抗融合活性。我们的结果可以添加有关基于DNA螺旋的抑制剂的构效关系的信息，并为后续的实验研究提供参考。