Monitoring SARS-CoV-2 Nsp13 helicase binding activity using expanded genetic code techniques
Eryn Lundrigan1, Christine Hum1, Nadine Ahmed1
1Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada john.pezacki@uottawa.ca.
RSC Chemical Biology
|May 1, 2025
Summary
Researchers developed a new method to study the SARS-CoV-2 Nsp13 helicase using fluorescent labeling. This technique helps understand enzyme activity and could lead to new pan-coronavirus therapies.
Area of Science:
- Biochemistry
- Molecular Biology
- Virology
Background:
- The SARS-CoV-2 Nsp13 helicase is crucial for viral replication and a potential target for broad-spectrum coronavirus treatments.
- Understanding its binding and unwinding mechanisms is key to developing effective therapeutics.
Purpose of the Study:
- To develop a method for site-specific fluorescent labeling of the Nsp13 helicase using non-canonical amino acids.
- To investigate the enzyme's substrate binding and translocation dynamics using Förster resonance energy transfer (FRET).
Main Methods:
- Genetic code expansion was used to incorporate *p*-azido-l-phenylalanine (AzF) into Nsp13 at five specific sites.
- The resulting Nsp13-AzF was labeled with a Cy5 fluorophore.
- FRET assays were employed to monitor enzyme-substrate interactions and translocation.
Main Results:
- Site-specific incorporation of AzF and Cy5 labeling did not impede Nsp13 helicase activity.
- FRET-based assays successfully monitored the binding dynamics of labeled Nsp13 constructs to nucleic acid substrates.
- The study demonstrated distance-dependent binding interactions.
Conclusions:
- This approach enables direct monitoring of Nsp13 helicase binding activity.
- The method offers a novel platform for screening inhibitors of this essential viral enzyme.
- This research contributes to the development of potential pan-coronavirus therapeutics.
Related Concept Videos
01:05Single Nucleotide Polymorphisms-SNPs
A single nucleotide polymorphism or SNP is a single nucleotide variation at a specific genomic position in a large population. It is the most prevalent type of sequence variation found in the human genome. Point mutations that occur in more than 1% of the population qualify as SNPs. These are present once every 1000 nucleotides on an average in the human genome. Replacement of a purine with another purine (A/G) or a pyrimidine with another pyrimidine (C/T) is known as a transition. In contrast,...
01:29Coronavirus
Coronaviruses, including the severe acute respiratory syndrome coronavirus (SARS-CoV), are enveloped viruses characterized by their single-stranded, positive-sense RNA genome and helical nucleocapsid structure. The hallmark of these viruses is their club-shaped spike (S) glycoproteins that protrude from the viral envelope, facilitating attachment to host cells. Typically, coronaviruses infect the upper respiratory tract, often causing mild or asymptomatic disease. However, certain strains like...