Nucleolin stabilizes G-quadruplex structures folded by the LTR promoter and silences HIV-1 viral transcription

Abstract

Folding of the LTR promoter into dynamic G-quadruplex conformations has been shown to suppress its transcriptional activity in HIV-1. Here we sought to identify the proteins that control the folding of this region of proviral genome by inducing/stabilizing G-quadruplex structures. The implementation of electrophorethic mobility shift assay and pull-down experiments coupled with mass spectrometric analysis revealed that the cellular protein nucleolin is able to specifically recognize G-quadruplex structures present in the LTR promoter. Nucleolin recognized with high affinity and specificity the majority, but not all the possible G-quadruplexes folded by this sequence. In addition, it displayed greater binding preference towards DNA than RNA G-quadruplexes, thus indicating two levels of selectivity based on the sequence and nature of the target. The interaction translated into stabilization of the LTR G-quadruplexes and increased promoter silencing activity; in contrast, disruption of nucleolin binding in cells by both siRNAs and a nucleolin binding aptamer greatly increased LTR promoter activity. These data indicate that nucleolin possesses a specific and regulated activity toward the HIV-1 LTR promoter, which is mediated by G-quadruplexes. These observations provide new essential insights into viral transcription and a possible low mutagenic target for antiretroviral therapy.

Cited by papers we hold 3

• Promoter G-quadruplexes and transcription factors cooperate to shape the cell type-specific transcriptome · 2021
  No notice
• A Fragment-Based Approach for the Development of G-Quadruplex Ligands: Role of the Amidoxime Moiety · 2018
  Not checked
• Nucleolin directly mediates Epstein-Barr virus immune evasion through binding to G-quadruplexes of EBNA1 mRNA · 2017
  No notice

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