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.
Anti-HIV-1 activity of the G-quadruplex ligand BRACO-19
