id9b00272_si_001.pdf (406.11 kB)
HIV‑1 Nucleocapsid Protein Unfolds Stable RNA G‑Quadruplexes in the Viral Genome and Is Inhibited by G‑Quadruplex Ligands
journal contribution
posted on 2019-11-05, 21:14 authored by Elena Butovskaya, Paola Soldà, Matteo Scalabrin, Matteo Nadai, Sara N. RichterThe G-quadruplexes that form in the
HIV-1 RNA genome hinder progression
of reverse transcriptase
in vitro, but not in infected cells. We investigated the possibility
that the HIV-1 nucleocapsid protein NCp7, which remains associated
with the viral RNA during reverse transcription, modulated HIV-1 RNA
G-quadruplex stability. By electrophoresis, circular dichroism, mass
spectrometry, and reverse transcriptase stop assays, we demonstrated
that NCp7 binds and unfolds the HIV-1 RNA G-quadruplexes and promotes
DNA/RNA duplex formation, allowing reverse transcription to proceed.
The G-quadruplex ligand BRACO-19 was able to partially counteract
this effect. These results indicate NCp7 as the first known viral
protein able to unfold RNA G-quadruplexes, and they explain how the
extra-stable HIV-1 RNA G-quadruplexes are processed; they also point
out that the reverse transcription process is hindered by G-quadruplex
ligands at both reverse transcriptase and NCp7 level. This information
can lead to the development of more effective anti-HIV-1 drugs with
a new mechanism of action.