Infection by choleraphage phi 138: bacteriophage DNA and replicative intermediates

Area of Science:

• Molecular Biology
• Virology
• Bacteriophage Research

Background:

• Choleraphage phi 138 possesses a unique linear, double-stranded, circularly permuted DNA genome.
• Bacteriophages are viruses that infect bacteria, playing crucial roles in microbial ecosystems and genetics.

Purpose of the Study:

• To elucidate the replication and packaging mechanisms of Choleraphage phi 138 DNA.
• To construct a physical map of the phi 138 genome using restriction enzymes.

Main Methods:

• DNA extraction and characterization of Choleraphage phi 138.
• Infection experiments with V. cholerae and analysis of host DNA degradation.
• Restriction endonuclease digestion (Bg/II, HindIII, PstI) for physical mapping.
• Identification and analysis of replicative DNA intermediates.

Main Results:

• Phi 138 DNA is a 45 kilobase pair molecule.
• Host DNA degradation occurs post-infection, with degradation products utilized for phage DNA synthesis.
• A physical map of the phi 138 genome was established.
• A concatemeric DNA intermediate, eight genome lengths long, was identified as a precursor to mature phage DNA.
• Mature phage DNA is packaged via a headful mechanism.

Conclusions:

• Choleraphage phi 138 employs host DNA for its replication, highlighting metabolic cooperation.
• The identification of a concatemeric intermediate and headful packaging mechanism provides insight into phage DNA maturation and assembly.