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Nucleoside triphosphate phosphohydrolase associated with cytoplasmic polyhedrosis virus
Journal of Biochemistry
|February 1, 1977
Summary
Silkworm cytoplasmic polyhedrosis virus contains a nucleoside triphosphate phosphohydrolase. This enzyme is crucial for mRNA 5'-terminal modification, initiating synthesis by hydrolyzing ATP.
Area of Science:
- Virology
- Enzymology
- Molecular Biology
Background:
- Silkworm cytoplasmic polyhedrosis virus (CPV) synthesizes mRNA with a 5'-terminal modification.
- The mechanism and enzymatic basis for this modification were not fully understood.
Purpose of the Study:
- To identify and characterize the enzyme responsible for the initial step in 5'-terminal mRNA modification in CPV.
- To investigate the properties and substrate specificity of this enzyme.
Main Methods:
- Enzyme assays using various nucleoside triphosphates and polynucleotides.
- Proteolytic treatment of CP virions to assess enzyme association.
Main Results:
- CP virus contains nucleoside triphosphate phosphohydrolase activity (EC 3.6.1.15).
- The enzyme preferentially hydrolyzes ATP and deoxy ATP, releasing orthophosphate.
- The phosphohydrolase activity is retained in partially degraded CP virions, indicating firm association.
- The enzyme functions independently of nucleic acid presence.
Conclusions:
- The identified phosphohydrolase is integral to the CP virion and essential for mRNA 5'-terminal modification.
- ATP hydrolysis by this enzyme is the first step in CP virus mRNA capping.