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Genetic analysis of bacteriophage phi29 of Bacillus subtilis: mapping of the cistrons coding for structural proteins
Abstract:
Four phage phi29 suppressor-sensitive mutants of cistron O have been examined for production of 14C-labeled viral-specific proteins in restrictive infections of Bacillus subtilis and fail to produce the protein of the viral neck lower collar. Cistrons O and F have been placed on the genetic map, containing 12 cistrons, by three-factor crosses. The phenotypes of five cistron J mutants have been analyzed by sodium dodecyl sulfate gel electrophoresis and autoradiography, and in three instances fragments of the normal polypeptide were detected. Three factor crosses with these mutants and a virus with a clear plaque phenotype were used to initiate the mapping of cistron J and the determination of the orientation of transcription in this map region.
Insights
Phage phi29 mutants in cistrons O and J were studied. Researchers identified specific viral protein production defects and mapped these cistrons on the phage genome using genetic crosses.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Phage phi29 is a well-studied model organism for DNA replication and gene expression.
- Understanding the genetic organization and protein function of bacteriophages is crucial for molecular biology research.
Purpose of the Study:
- To analyze the function of phage phi29 cistrons O and J.
- To genetically map these cistrons within the phage phi29 genome.
- To investigate the production of viral-specific proteins in mutant strains.
Main Methods:
- Utilized suppressor-sensitive mutants of phage phi29 cistron O.
- Performed restrictive infections in Bacillus subtilis.
- Analyzed 14C-labeled viral-specific protein production.
- Employed three-factor crosses for genetic mapping.
- Used sodium dodecyl sulfate gel electrophoresis and autoradiography for protein analysis.
Main Results:
- Mutants of cistron O failed to produce the viral neck lower collar protein.
- Cistrons O and F were mapped on a 12-cistron genetic map.
- Analysis of five cistron J mutants revealed polypeptide fragments in three cases.
- Initiated mapping of cistron J and determined transcriptional orientation.
Conclusions:
- Cistron O is essential for the production of a specific viral structural protein.
- Genetic mapping provides insights into the organization of the phage phi29 genome.
- Further characterization of cistron J mutants aids in understanding phage gene expression and assembly.