Related Experiment Videos
mRNA capping enzymes are masked in reovirus progeny subviral particles
Abstract:
We examined the enzyme activities associated with progeny subviral particles isolated from L-cells infected with reovirus at 12 h postinfection. Activities normally present in reovirus cores were also found to be present in the progeny subviral particles, with the exception of the capping enzymes. The methylase and guanyl transferase activities, which constitute the capping system, were present in a masked form that could be activated by chymotrypsin digestion. The appearance of these progeny subviral particles in infected cells coincided with the time when mRNA synthesis was maximal, suggesting that viral mRNA synthesized at later times is uncapped.
Insights
Reovirus progeny subviral particles contain masked capping enzymes, activated by chymotrypsin. This suggests later viral mRNA synthesis in infected cells produces uncapped messenger RNA.
Area of Science:
- Virology
- Molecular Biology
- Enzymology
Background:
- Reovirus is a non-enveloped dsRNA virus that replicates in the cytoplasm of infected cells.
- Subviral particles (SVPs) are intermediates in the reovirus replication cycle, formed after the removal of the outer capsid.
- Capping is a crucial post-transcriptional modification of eukaryotic mRNA, essential for translation and stability.
Purpose of the Study:
- To investigate the enzyme activities present in reovirus progeny subviral particles.
- To determine the status of capping enzyme activity in these particles.
- To correlate the presence and activity of capping enzymes with viral mRNA synthesis.
Main Methods:
- Isolation of progeny subviral particles from L-cells infected with reovirus.
- Assay of enzyme activities, including methylase and guanyl transferase, in isolated particles.
- Activation of masked enzyme activities using chymotrypsin digestion.
Main Results:
- Progeny subviral particles exhibited enzyme activities similar to reovirus cores.
- Capping enzymes (methylase and guanyl transferase) were present but masked in progeny SVPs.
- Chymotrypsin digestion unmasked and activated the capping enzyme activities.
- The appearance of these SVPs coincided with maximal viral mRNA synthesis.
Conclusions:
- Reovirus progeny SVPs contain latent capping enzymes.
- Viral mRNA synthesized during peak replication may be uncapped due to the masked state of these enzymes.
- This finding has implications for understanding reovirus gene expression and replication strategies.