The Bacteriophage Lambda CII Phenotypes for Complementation, Cellular Toxicity and Replication Inhibition Are...

Area of Science:

• Molecular Biology
• Bacteriophage Genetics

Background:

• The temperate bacteriophage lambda (λ) CII protein regulates transcription from promoter pE, crucial for the lysogenic response.
• Understanding CII's regulation is key to deciphering lambda's developmental pathways.

Purpose of the Study:

• To investigate the regulatory role of the small RNA OOP on bacteriophage lambda (λ) CII protein activities.
• To determine if OOP RNA can suppress CII-mediated functions, including lysogenic complementation, cell toxicity, and plasmid loss.

Main Methods:

• Examined CII expression in vectors lacking phage transcription-modulating elements.
• Assessed the impact of OOP RNA expression on CII complementation, toxicity, and ColE1 plasmid stability.
• Investigated the role of specific promoter sequences (pO45, pO94) and CII protein domains (COOH-terminal deletion).
• Analyzed the influence of host mutations (hflA, pcnB, rpoB) on CII activities.

Main Results:

• OOP RNA expression from the pO-oop-to genetic element suppressed CII's ability to complement for a lysogenic response.
• A longer pO promoter sequence (pO94) prevented CII complementation, CII-dependent plasmid loss, and suppressed CII toxicity.
• Deletion of the COOH-terminal 20 amino acids of CII eliminated all tested CII activities.
• Host mutations in hflA, pcnB, and rpoB significantly influenced CII activities.

Conclusions:

• OOP RNA acts as a potent regulatory pivot in lambda (λ) development by suppressing CII activities.
• The COOH-terminal end of CII likely interacts with the β-subunit of RNA polymerase, mediating its functions.
• The pO promoter's DNA sequence length is critical for its regulatory function in controlling CII activity.