Interference with phage lambda development by the small subunit of the phage 21 terminase, gp1.

Area of Science:

• Molecular Biology
• Virology
• Genetics

Background:

• Bacteriophage lambda development can be inhibited by factors from other phages, such as phage 21's terminase subunit gp1.
• Understanding these interactions is crucial for phage biology and genetic engineering.
• The Nul and A genes in bacteriophage lambda are known to overlap.

Purpose of the Study:

• To investigate the mechanism by which bacteriophage 21 terminase subunit gp1 inhibits bacteriophage lambda development.
• To identify and characterize mutations in bacteriophage lambda that confer resistance to gp1-mediated inhibition.
• To elucidate the role of gene expression regulation in bacteriophage interactions.

Main Methods:

• Genetic analysis of bacteriophage lambda mutants resistant to phage 21 gp1 inhibition.
• Site-directed mutagenesis to introduce specific mutations, such as sti30.
• Construction and analysis of reporter gene fusions (Nul-lacZ) to quantify gene expression.
• Assessment of phage plaque formation assays in the presence of gp1.

Main Results:

• The small subunit of phage 21 terminase, gp1, inhibits bacteriophage lambda development.
• A specific mutation, sti30, in bacteriophage lambda confers resistance to gp1 inhibition.
• The sti30 mutation enhances the ribosome-binding site of the Nul gene, increasing Nul gene expression approximately 50-fold.
• This increased Nul gene expression is responsible for overcoming gp1 inhibition.
• The sti30 mutation does not significantly affect the expression of the overlapping A gene, suggesting a lack of translational coupling.

Conclusions:

• The bacteriophage 21 terminase subunit gp1 inhibits lambda development by interfering with Nul gene expression.
• The sti30 mutation in lambda enhances Nul gene translation initiation, thereby overcoming gp1-mediated inhibition.
• Translational coupling between the Nul and A genes in lambda is minimal or absent, as indicated by the specific effect of the sti30 mutation.