Probing the Importance of the G-Quadruplex Grooves for the Activity of the Anti-HIV-Integrase Aptamer T30923.

Veronica Esposito,Francesca Esposito,Enzo Tramontano,Antonella Virgilio,Isabel Gomez Monterrey,Luciano Mayol,Antonietta Pepe,Aldo Galeone

doi:10.3390/ijms21165637

Abstract

In this paper, we report studies concerning four variants of the G-quadruplex forming anti-HIV-integrase aptamer T30923, in which specific 2′-deoxyguanosines have been singly replaced by 8-methyl-2′-deoxyguanosine residues, with the aim to exploit the methyl group positioned in the G-quadruplex grooves as a steric probe to investigate the interaction aptamer/target. Although, the various modified aptamers differ in the localization of the methyl group, NMR, circular dichroism (CD), electrophoretic and molecular modeling data suggest that all of them preserve the ability to fold in a stable dimeric parallel G-quadruplex complex resembling that of their natural counterpart T30923. However, the biological data have shown that the T30923 variants are characterized by different efficiencies in inhibiting the HIV-integrase, thus suggesting the involvement of the G-quadruplex grooves in the aptamer/target interaction.

Highlights

Acquired immune deficiency syndrome (AIDS) is a disease of the human immune system, whose etiological agent is the human immunodeficiency virus (HIV), belonging to the Retroviridae family
We exploited the methyl group of an 8-methyl-2 -deoxyguanosine residue as a steric probe to investigate the importance of the grooves for the inhibiting activity of a G4 anti-HIV-integrase aptamer, namely T30923, adopting a parallel-stranded G4 dimer structure, in which only anti-2 -deoxyguanosines occur
A series of four T30923 analogues were prepared in which the canonical 2 -deoxyguanosine residues involved in the formation of the central G-tetrad were replaced, one at a time, with an 8-methyl-2 -deoxyguanosine one

Summary

Introduction

Acquired immune deficiency syndrome (AIDS) is a disease of the human immune system, whose etiological agent is the human immunodeficiency virus (HIV), belonging to the Retroviridae family. About 35 million people are infected with HIV worldwide and considering 2 million new infections and about 1.6 million deaths from this disease per year, AIDS is still a global emergency. Aptamers are DNA or RNA ligands able to compete with antibodies in therapeutic, analytic and diagnostic applications, thanks to their capacity to interact with high affinity and specificity with a given target molecule [2]. These ligands can be discovered fortuitously, through several combinatorial approaches collectively called Systematic Evolution of Ligands by Exponential Enrichment (SELEX) or by other techniques [3]. Thanks to their stacked G-tetrads (each stabilized by eight H-bonds) and a monovalent metal ion between them, this DNA or RNA conformation is considered among the most stable ones

Methods

Discussion

Conclusion