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Polypeptide synthesis directed by bacteriophage phi W-14 and by mutants defective in DNA synthesis
Abstract:
The latent period of bacteriophage phi W-14 is approximately 65 min when the doubling time of its host, Pseudomonas acidovorans, is 85 min. Host protein synthesis is shut off relatively slowly, stopping approximately 25 min after infection. There are several phases of phage-specific polypeptide synthesis during the latent period: early polypeptides appear within 10 min after infection; middle polypeptides start to appear between 10 nd 30 min; late polypeptides appear after 30 min. The lengths of time for which individual polypeptides are synthesized vary widely. Several late polypeptides do not appear in the virion. DNA replication is not required for late gene expression. The hypermodified pyrimidine, alpha-putrescinylthymine, appears not to be required in both strands of the DNA duplex for transcription.
Insights
Bacteriophage phi W-14 infection of Pseudomonas acidovorans shows distinct phases of protein synthesis and gene expression. Late gene expression occurs independently of DNA replication, with a unique pyrimidine not essential for transcription.
Area of Science:
- Microbiology
- Molecular Biology
- Virology
Background:
- Bacteriophage phi W-14 infects the bacterium Pseudomonas acidovorans.
- Understanding phage-host interactions and gene expression is crucial in virology.
Purpose of the Study:
- To characterize the latent period of bacteriophage phi W-14 infection.
- To investigate the temporal patterns of phage-specific polypeptide synthesis.
- To determine the role of DNA replication and a specific pyrimidine in late gene expression.
Main Methods:
- Monitoring host protein synthesis shut-off post-infection.
- Analyzing the temporal appearance of early, middle, and late phage polypeptides.
- Assessing the impact of DNA replication inhibition on late gene expression.
- Evaluating the necessity of alpha-putrescinylthymine for transcription.
Main Results:
- The latent period was approximately 65 min with a host doubling time of 85 min.
- Host protein synthesis ceased around 25 min post-infection.
- Phage polypeptides were synthesized in distinct early, middle, and late phases.
- Late gene expression proceeded even without DNA replication.
- The hypermodified pyrimidine alpha-putrescinylthymine was not required in both DNA strands for transcription.
Conclusions:
- Bacteriophage phi W-14 exhibits complex temporal regulation of gene expression during its latent period.
- Late gene expression in this system is independent of viral DNA replication.
- The unusual pyrimidine alpha-putrescinylthymine plays a non-essential role in transcription initiation.