Bacteriophage lambda PaPa: not the mother of all lambda phages

Area of Science:

• Microbiology
• Molecular Biology
• Virology

Background:

• The common laboratory strain of bacteriophage lambda, lambda wild type (or lambda PaPa), differs from the original isolate, Ur-lambda.
• Lambda wild type possesses a frameshift mutation compared to Ur-lambda, affecting its virion structure and function.

Purpose of the Study:

• To investigate the structural and functional differences between Ur-lambda and lambda wild type bacteriophages.
• To identify the genetic basis for the presence of tail fibers in Ur-lambda virions.

Main Methods:

• Comparative analysis of bacteriophage lambda strains (Ur-lambda and lambda wild type).
• Genetic analysis to identify genes responsible for tail fiber production and assembly.

Main Results:

• Ur-lambda virions possess thin, jointed tail fibers, which are absent in lambda wild type.
• Two novel proteins, encoded by the stf and tfa genes, constitute the Ur-lambda tail fibers.
• The stf gene is disrupted by the frameshift mutation in lambda wild type; the tfa gene is involved in tail fiber assembly.
• Ur-lambda exhibits expanded receptor specificity and faster adsorption to Escherichia coli cells compared to lambda wild type.

Conclusions:

• The frameshift mutation in lambda wild type disrupts the genes responsible for tail fiber production, leading to their absence.
• The stf and tfa gene products are essential for Ur-lambda tail fiber formation and function.
• Ur-lambda's tail fibers contribute to its enhanced receptor specificity and adsorption rate to Escherichia coli.