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Genomic location of a human cytomegalovirus protein with protein kinase activity (PK68)
T Somogyi1, S Michelson, M J Masse
1Unité de Virologie Médicale, Institut Pasteur, Paris, France.
Abstract:
A major protein of Mr 68,000 with a previously described protein kinase activity (PK68), which is induced in HCMV-infected cells, is shown to be virus encoded by means of hybrid selection. The gene coding for the corresponding 4-kb mRNA was located within map units 0.510 and 0.525. This location is the same as that of pp65, a structural protein with no attributed function. The early nature of the protein was confirmed with its mRNA first appearing 3 hr after infection under cycloheximide reversal and phosphonoacetic acid blocking conditions. Another mRNA, 97 nucleotides smaller and 5' coterminal with PK68, which codes for a Mr 52,000 protein, was also observed.
Insights
Human cytomegalovirus (HCMV) encodes a 68,000-dalton protein kinase (PK68). Its gene is located near the pp65 gene, and its mRNA appears early after infection.
Area of Science:
- Virology
- Molecular Biology
- Protein Biochemistry
Background:
- Human cytomegalovirus (HCMV) infection involves numerous viral proteins.
- A previously identified protein kinase activity (PK68) is induced during HCMV infection.
- The origin and function of PK68 have remained unclear.
Purpose of the Study:
- To determine if the protein kinase PK68 is encoded by the HCMV genome.
- To identify the gene locus and temporal expression pattern of PK68 mRNA.
- To characterize related viral transcripts.
Main Methods:
- Hybrid selection was used to identify virus-encoded proteins.
- Gene mapping was performed using the HCMV genome map.
- Northern blot analysis and mRNA size determination were conducted.
Main Results:
- Hybrid selection confirmed that PK68 is HCMV-encoded.
- The gene for the 4-kb PK68 mRNA was mapped to HCMV map units 0.510-0.525.
- This locus overlaps with the gene for the structural protein pp65.
- PK68 mRNA was detected as early as 3 hours post-infection, indicating an early viral gene.
- A smaller, 5' coterminal mRNA encoding a 52,000-dalton protein was also identified.
Conclusions:
- The protein kinase PK68 is a virus-encoded protein of HCMV.
- The PK68 gene is located in a region overlapping with the pp65 gene.
- PK68 is an early viral protein, suggesting a role in the initial stages of HCMV infection.