Comparative genetics of the T-even bacteriophages

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• T-even bacteriophages (T2, T4, T6) are widely studied models in molecular biology.
• Amber mutants are crucial tools for genetic analysis of bacteriophages.
• Existing amber mutant systems in T4 bacteriophage provide a basis for comparison.

Purpose of the Study:

• To develop and characterize amber mutant systems for T2 and T6 bacteriophages.
• To compare the genetic makeup and organization of T2 and T6 with T4.
• To investigate the potential for genetic exchange and evolutionary relationships among these phages.

Main Methods:

• Development of amber mutant libraries for T2 and T6 bacteriophages.
• Genetic mapping using recombination analysis and a modified mapping function.
• Comparative analysis of gene homology and functional complementation of gene products.

Main Results:

• Identified 52 genes in T2 and 45 genes in T6, with high homology to T4 genes.
• Recombination in T2 and T6 exhibited negative interference, correctable by a T4-specific mapping function.
• Recombinational maps showed similar gene order and spacing to T4, except for the tail fiber region.
• Homologous gene products were largely interchangeable, with exceptions in co-adapted tail fiber genes (37 and 38).

Conclusions:

• T2, T4, and T6 bacteriophages share significant genetic similarity, suggesting an analogous relationship to biological races.
• Despite genetic differences and incipient isolating mechanisms, these phages retain the capacity for genetic exchange.
• The study provides insights into bacteriophage evolution and the mechanisms of genetic interaction.