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Protein cleavage in virus-infected cells.
Acta Biologica Et Medica Germanica
|January 1, 1977
Summary
Picornavirus infection inactivates a host cell protease. A new viral protease then emerges, crucial for poliovirus replication and protein processing, as shown by a temperature-sensitive mutant study.
Area of Science:
- Virology
- Molecular Biology
- Enzymology
Background:
- HeLa cells possess a trypsin-like endoprotease on ribosomes.
- Picornavirus infection leads to the loss of this host protease activity.
- Viral protein synthesis and processing correlate with the decline in host protease function.
Purpose of the Study:
- To investigate the role of proteolytic enzymes in HeLa cells during picornavirus infection.
- To characterize the changes in protease activity following infection.
- To elucidate the mechanism of poliovirus replication involving specific proteolysis.
Main Methods:
- Solid-phase assay for proteolytic enzymes using viral precursor polypeptides.
- Analysis of protease activity in infected and uninfected HeLa cells.
- Isolation and characterization of a temperature-sensitive viral protease mutant.
Main Results:
- Host cell trypsin-like endoprotease activity decreases post-picornavirus infection.
- Inhibition of host protease activity observed with trypsin inhibitors and double-stranded RNA.
- A new protease with enhanced specificity for viral substrates is synthesized after infection.
- The viral protease exhibits distinct pH optimum and heat stability compared to host enzymes.
- A temperature-sensitive poliovirus mutant confirmed the role of a viral gene product in proteolysis.
Conclusions:
- Poliovirus replication is regulated by specific proteolysis.
- A poliovirus gene product is enzymatically involved in cleaving viral proteins.
- A model for poliovirus replication involving specific proteolysis is proposed.