Coliphage P1 morphogenesis: analysis of mutants by electron microscopy

Area of Science:

• Microbiology
• Molecular Biology
• Structural Biology

Background:

• Bacteriophage P1 is a model organism for studying viral structure and assembly.
• Understanding phage morphogenesis is crucial for developing phage-based therapies and genetic tools.

Purpose of the Study:

• To genetically and phenotypically characterize bacteriophage P1 mutants with defects in particle morphogenesis.
• To identify and map novel genes involved in P1 head and tail assembly.

Main Methods:

• Electron microscopy was employed to visualize phage particle defects.
• Serum blocking power tests were used to assess mutant phenotypes.
• Complementation tests, genetic mapping, and physical mapping were utilized to assign mutations to genes.

Main Results:

• 47 amber mutants with morphogenesis defects were analyzed, revealing 11 head, 30 tail, and 6 maturation defects.
• A minimum of 12 tail genes, 4 head genes, and 1 maturation gene were identified.
• Specific tail genes were assigned functions including tail fiber, baseplate, sheath, length, and stability.
• Head genes were implicated in DNA packaging and structural protein components.

Conclusions:

• The study significantly expands the known gene set for P1 morphogenesis.
• Identified P1 morphogenetic gene clusters are interrupted by other genes, suggesting complex genome organization.
• This work provides a foundation for further investigation into P1 assembly mechanisms.