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Protease of adenovirus type 2. Subcellular localization
The Journal of Biological Chemistry
|December 25, 1979
Summary
Adenovirus type 2 protease activity is found within infected cell nuclei and virions, essential for viral maturation. This internal protease processes precursor molecules, indicating its critical role in forming infectious adenovirions.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Adenovirus type 2 protease is crucial for viral maturation.
- Its subcellular localization and role in processing viral proteins were previously unclear.
Purpose of the Study:
- To investigate the subcellular localization of adenovirus type 2 protease activity.
- To determine the role of this protease in viral particle formation and maturation.
Main Methods:
- In vitro protease assay system using infected cell extracts and purified virions.
- Enzyme inhibition assays with L-1-tosylamide-2-phenylethylchloromethyl ketone and phenylmethylsulfonyl fluoride.
- Analysis of protease activity in precursor virus particles (top components) and temperature-sensitive mutants (H2ts1).
Main Results:
- Protease activity was exclusively localized to infected cell nuclei and insoluble fractions.
- Activity was detected in young virions containing precursor polypeptide VII (PVII).
- Protease was internally located within virions, becoming sensitive to inhibitors only after sonication.
- Protease processed exogenous PVII to polypeptide VII.
- Noninfectious H2ts1 virions lacked protease activity.
Conclusions:
- Adenovirus type 2 protease enters precursor particles with the viral chromosome.
- The protease is essential for processing PVII and subsequent maturation of infectious adenovirions.