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Properties of a human cytomegalovirus-induced protein kinase
Abstract:
A human cytomegalovirus (HCMV)-induced polypeptide of 68,000 Da (p68) with protein kinase activity was identified using a monoclonal antibody (F6b) produced against HCMV-infected cell proteins. p68 was detected by immunoprecipitation from 3 to 120 hr after infection and was induced by several strains of human and not simian CMV. Protein kinase activity was associated almost exclusively with nuclear HCMV-induced p68. Enzyme activity with ATP and casein as phosphate donor and acceptor, respectively, exhibited an optimum pH between 6 and 6.5. It was Mg2+ dependent and cAMP independent. The KATPm of 45 microM at pH 6.5 indicated a relatively high affinity of p68 for the nucleotide. p68 also transferred phosphate to phosvitin and light chains of F6b, as well as autophosphorylating at threonine and serine residues.
Insights
Researchers identified a human cytomegalovirus (HCMV)-induced protein (p68) with kinase activity. This nuclear protein, essential for HCMV infection, phosphorylates various substrates, offering potential therapeutic targets.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Human cytomegalovirus (HCMV) is a significant human pathogen.
- Viral proteins play crucial roles in HCMV replication and pathogenesis.
- Understanding viral enzyme functions is key to developing antiviral strategies.
Purpose of the Study:
- To identify and characterize a novel HCMV-induced protein with enzymatic activity.
- To investigate the biochemical properties and substrate specificity of the identified protein kinase.
Main Methods:
- Production of a monoclonal antibody (F6b) against HCMV-infected cell proteins.
- Immunoprecipitation to detect the HCMV-induced polypeptide (p68).
- In vitro kinase assays to determine enzyme activity, optimal conditions, and substrate preference.
Main Results:
- Identification of a 68,000 Da (p68) polypeptide induced by HCMV, specifically human strains.
- p68 exhibits protein kinase activity, predominantly in the nucleus of infected cells.
- The enzyme is Mg2+ dependent, cAMP independent, with optimal activity at pH 6-6.5, and phosphorylates casein, phosvitin, and F6b light chains.
Conclusions:
- A novel HCMV-encoded protein kinase (p68) has been identified and characterized.
- p68 possesses significant kinase activity and autophosphorylation capability.
- This viral kinase represents a potential target for antiviral therapies against HCMV.