Related Experiment Video
Updated: Sep 4, 2025
Engineering Antiviral Agents via Surface Plasmon Resonance
Published on: June 14, 2022
Binding Adaptation of GS-441524 Diversifies Macro Domains and Downregulates SARS-CoV-2 de-MARylation Capacity
Aikaterini C Tsika1, Angelo Gallo1, Nikolaos K Fourkiotis1
1Department of Pharmacy, University of Patras, GR-26504 Patras, Greece.
Abstract:
Viral infection in cells triggers a cascade of molecular defense mechanisms to maintain host-cell homoeostasis. One of these mechanisms is ADP-ribosylation, a fundamental post-translational modification (PTM) characterized by the addition of ADP-ribose (ADPr) on substrates. Poly(ADP-ribose) polymerases (PARPs) are implicated in this process and they perform ADP-ribosylation on host and pathogen proteins. Some viral families contain structural motifs that can reverse this PTM. These motifs known as macro domains (MDs) are evolutionarily conserved protein domains found in all kingdoms of life. They are divided in different classes with the viral belonging to Macro-D-type class because of their properties to recognize and revert the ADP-ribosylation. Viral MDs are potential pharmaceutical targets, capable to counteract host immune response. Sequence and structural homology between viral and human MDs are an impediment for the development of new active compounds against their function. Remdesivir, is a drug administrated in viral infections inhibiting viral replication through RNA-dependent RNA polymerase (RdRp). Herein, GS-441524, the active metabolite of the remdesivir, is tested as a hydrolase inhibitor for several viral MDs and for its binding to human homologs found in PARPs. This study presents biochemical and biophysical studies, which indicate that GS-441524 selectively modifies SARS-CoV-2 MD de-MARylation activity, while it does not interact with hPARP14 MD2 and hPARP15 MD2. The structural investigation of MD•GS-441524 complexes, using solution NMR and X-ray crystallography, discloses the impact of certain amino acids in ADPr binding cavity suggesting that F360 and its adjacent residues tune the selective binding of the inhibitor to SARS-CoV-2 MD.
Insights
GS-441524, remdesivir
Area of Science:
- Molecular biology and virology
- Biochemistry and structural biology
Background:
- Viral infections trigger host defense mechanisms, including ADP-ribosylation, a post-translational modification (PTM) regulated by Poly(ADP-ribose) polymerases (PARPs).
- Viruses possess Macro Domains (MDs) that reverse ADP-ribosylation, acting as potential pharmaceutical targets to counteract host immune responses.
- Structural homology between viral and human MDs hinders the development of selective inhibitors.
Purpose of the Study:
- To investigate GS-441524, the active metabolite of remdesivir, as a hydrolase inhibitor for viral MDs.
- To assess the binding of GS-441524 to human MD homologs in PARPs.
- To elucidate the structural basis for selective inhibition of viral MDs by GS-441524.
Main Methods:
- Biochemical and biophysical assays were employed to study hydrolase inhibition and binding interactions.
- Solution Nuclear Magnetic Resonance (NMR) and X-ray crystallography were used for structural investigations.
- Comparative analysis of viral and human MDs in complex with GS-441524.
Main Results:
- GS-441524 selectively inhibits the de-ADP-ribosylation activity of the SARS-CoV-2 Macro Domain (MD).
- GS-441524 does not interact with human PARP14 MD2 and PARP15 MD2.
- Structural studies reveal that specific amino acids, such as F360, within the ADPr binding cavity dictate selective inhibitor binding to SARS-CoV-2 MD.
Conclusions:
- GS-441524 demonstrates selective inhibitory activity against viral MDs, offering a potential therapeutic strategy.
- The findings highlight the potential of targeting viral MDs for antiviral drug development.
- Understanding the structural determinants of selective binding can guide the design of novel antiviral compounds.
