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Coliphage BA14: a new relative of phage T7
Abstract:
Coliphage BA14 was isolated from sewage and shown to be related to phages T7 and T3. It is similar to T3 in that it directs the synthesis of an S-adenosyl-methionine-cleaving enzyme (SAMase) early upon infection. However, it differs from all other known T7-related coliphages by the inability of its RNA polymerase (gene 1 product) to transcribe T7 DNA or T3 DNA. BA14, T7 and T3 also show marked differences in autoradiographic patterns of their gel-electrophoretically separated 35S-labelled intracellular phage proteins, restriction endonuclease HpaI cleavage patterns of their DNAs, and serological specificities of their infectious particles. Other distinctive features became apparent upon simultaneous mixed infection with BA14 and T7 or T3: inability of BA14 to produce genetic recombinants with either T7 or T3; lack of functional complementation between amber mutants of BA14 and T7 or T3; mutual exclusion and depression of the burst size of the mixedly infected cells.
Insights
Coliphage BA14, isolated from sewage, shows unique characteristics compared to T7 and T3 phages. Its RNA polymerase cannot transcribe related phage DNA, and it fails to recombine or complement with T7 or T3.
Area of Science:
- Microbiology
- Virology
- Molecular Biology
Background:
- Bacteriophages are viruses that infect bacteria, playing crucial roles in microbial ecosystems and molecular biology research.
- Coliphages, such as T7 and T3, are well-studied models for understanding viral replication and gene expression.
- The genetic and functional diversity among related bacteriophages is essential for evolutionary studies.
Purpose of the Study:
- To isolate and characterize a novel coliphage, BA14, from sewage.
- To compare the biological and genetic properties of coliphage BA14 with the related coliphages T7 and T3.
- To investigate the functional interactions between coliphage BA14 and coliphages T7/T3 during mixed infections.
Main Methods:
- Isolation and characterization of coliphage BA14 from environmental samples.
- Analysis of phage-encoded enzymes, specifically S-adenosyl-methionine-cleaving enzyme (SAMase) synthesis.
- Assessment of RNA polymerase activity using transcription assays with heterologous phage DNA.
- Comparative analysis of intracellular phage protein profiles using SDS-PAGE and autoradiography.
- DNA restriction fragment analysis using HpaI endonuclease.
- Serological characterization of infectious phage particles.
- Mixed infection experiments to evaluate genetic recombination, functional complementation, and interference phenomena.
Main Results:
- Coliphage BA14 directs the early synthesis of SAMase, similar to T3 phage.
- BA14's RNA polymerase is incapable of transcribing T7 or T3 DNA, distinguishing it from other T7-related coliphages.
- Significant differences were observed in protein profiles, DNA restriction patterns, and serological specificities between BA14, T7, and T3.
- Mixed infections with BA14 and T7/T3 resulted in the inability to produce genetic recombinants and a lack of functional complementation.
- Mutual exclusion and a reduced burst size were observed in cells coinfected with BA14 and T7/T3.
Conclusions:
- Coliphage BA14 represents a distinct lineage within the T7-related coliphage group, exhibiting unique transcriptional and genetic properties.
- The inability of BA14's RNA polymerase to transcribe T7/T3 DNA suggests significant evolutionary divergence or unique regulatory mechanisms.
- BA14 interferes with the replication of T7 and T3, indicating potential mechanisms of viral antagonism or competition within a single host cell.