A third defective lambdoid prophage of Escherichia coli K12 defined by the lambda derivative, lambdaqin111

Area of Science:

• Microbiology
• Bacteriology
• Molecular Biology

Background:

• Bacteriophage lambda is a well-studied model organism in molecular biology.
• Lambda phages integrate into the bacterial chromosome as prophages.
• Characterization of phage mutants aids in understanding gene function and regulation.

Purpose of the Study:

• To isolate and characterize a novel Q-independent mutant of bacteriophage lambda.
• To investigate the genetic basis and chromosomal location of this new mutant.
• To determine the functional elements present in the newly identified prophage.

Main Methods:

• Isolation and characterization of lambdaqin111 mutant.
• Homologous recombination assays to study integration.
• DNA/DNA hybridization for genetic relatedness.
• Genetic analysis and electron microscopy.
• Bacterial chromosome mapping.

Main Results:

• A new Q-independent lambda mutant, lambdaqin111, was successfully isolated and characterized.
• Evidence indicates lambdaqin111 defines a novel lambda-like prophage integrated into the bacterial chromosome.
• Homologous recombination and DNA hybridization confirmed the prophage's presence and relationship to lambda.
• Genetic and microscopy data revealed the prophage contains genes analogous to lambda's Q-S-R and a functional lambda cos site.
• The new prophage is mapped to the Escherichia coli K12 chromosome near 34 min, distinct from the Rac prophage.

Conclusions:

• The discovery of lambdaqin111 reveals a new lambda-like prophage in Escherichia coli K12.
• This prophage possesses key genetic elements (Q-S-R, cos site) functional for phage replication and integration.
• The prophage's location near the Rac prophage site provides insights into bacterial genome organization and phage-host dynamics.