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Structure and expression of the vaccinia virus gene which prevents virus-induced breakdown of RNA
R F Pacha1, R J Meis, R C Condit
1Department of Biochemistry, State University of New York, Buffalo 14214.
Abstract:
Three noncomplementing vaccinia virus temperature-sensitive mutants, ts4, ts22, and ts23, exhibit an abortive late phenotype characterized by the simultaneous cessation of protein synthesis, the breakdown of rRNA and viral mRNA, and an increase in intracellular concentrations of 2'-5'-linked oligoadenylates late during infection at the nonpermissive temperature (R.F. Pacha and R.C. Condit, J. Virol. 56:395-403, 1985; R.J. Cohrs, R.C. Condit, R.F. Pacha, C.L. Thompson, and O.K. Sharma, J. Virol. 63:948-951, 1989). We have identified the virus gene affected by the abortive late mutants, determined its DNA sequence, and analyzed its transcription. The gene resides in the HindIII A DNA fragment, it has a predicted coding capacity of 57 kilodaltons, and it is transcribed both early and late during infection. The early transcript of the abortive late gene is unusual; it contains a 426-nucleotide 5' untranslated region, and it must be synthesized by transcription through an early transcription termination signal which is located in the middle of the gene in a hairpin loop structure. DNA sequence and transcription analysis of two flanking genes is also presented.
Insights
Researchers identified a vaccinia virus gene responsible for an abortive late phenotype. This gene
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Vaccinia virus temperature-sensitive mutants (ts4, ts22, ts23) display an abortive late phenotype.
- This phenotype includes halted protein synthesis, rRNA/mRNA degradation, and increased 2'-5'-linked oligoadenylates at nonpermissive temperatures.
- Previous studies established the characteristics of these mutants.
Purpose of the Study:
- To identify the specific vaccinia virus gene affected by the abortive late mutants.
- To determine the DNA sequence and analyze the transcription of this identified gene.
- To investigate the characteristics of the early transcript and flanking genes.
Main Methods:
- Identification of the affected gene within the HindIII A DNA fragment.
- DNA sequencing to determine the gene's sequence.
- Transcription analysis to study gene expression patterns.
Main Results:
- The identified gene has a predicted coding capacity of 57 kilodaltons.
- The gene is transcribed during both early and late stages of infection.
- The early transcript features a long 5' untranslated region and unusual transcription through a hairpin loop termination signal.
Conclusions:
- A novel vaccinia virus gene critical for late-stage replication has been identified.
- The unusual transcription of the early transcript suggests complex regulatory mechanisms.
- Further analysis of this gene and flanking regions is warranted to understand vaccinia virus replication.