Protein cleavage in virus-infected cells.
A variety of proteins, including viral precursor polypeptides, were bound to a solid support and used in a sensitive assay for proteolytic enzymes in HeLa cells. A trypsin-like endoprotease, present on ribosomes of HeLa cells, loses activity after picornavirus infection. The decline follows synthesis and processing of a viral protein. Inhibition of cellfree activity of HeLa protease occurs when protein trypsin inhibitors or double-stranded RNA are added. After the mid-point of infection, protease activity with enhanced specificity for viral substrates is detected. The new protease has a pH optimum and heat stability different from endogenous host enzymes, and is synthesized following infection. A viral mutant was isolated which produces a temperature-sensitive protease. The results indicate that a poliovirus gene product participates enzymatically in the final cleavages of some polioviral proteins. A model for the regulation of poliovirus replication based on specific proteolysis is presented.
D002472:Cell Transformation, Viral; D010450:Endopeptidases / Q000378:metabolism*; D006367:HeLa Cells / Q000201:enzymology*; D007700:Kinetics; D008954:Models, Biological; D010849:Picornaviridae; D012270:Ribosomes / Q000201:enzymology; D014361:Trypsin Inhibitors / Q000494:pharmacology; D014764:Viral Proteins; D014779:Virus Replication
D014361:Trypsin Inhibitors; D014764:Viral Proteins; D010450:Endopeptidases