Translation initiation of bacteriophage lambda gene cII requires integration host factor

Area of Science:

• Molecular Biology
• Bacteriology
• Genetics

Background:

• Escherichia coli integration host factor (IHF) is a DNA-binding protein.
• IHF positively regulates the expression of the lambda cII gene.

Purpose of the Study:

• To investigate the direct role of IHF in lambda cII gene expression.
• To identify the specific sequences and mechanisms by which IHF controls cII translation.

Main Methods:

• In vitro protein synthesis assays using purified IHF.
• Construction and analysis of operon and gene fusions (cII-lacZ, cII-galE) in vivo.
• Analysis of IHF-dependent translation initiation and transcription termination.

Main Results:

• IHF is essential for the initiation of cII translation in vivo.
• Sequences critical for IHF-dependent translation lie between the ribosome binding site and the cII initiating codon.
• Failure to translate cII activates a downstream transcription terminator, causing polar effects suppressed by lambda N.
• IHF binding may prevent RNA duplex formation that sequesters the ribosome binding site.

Conclusions:

• IHF plays a direct and essential role in initiating lambda cII translation.
• IHF influences cII expression by modulating RNA structure and ribosome accessibility.
• Understanding IHF's role provides insight into bacterial gene regulation and phage-lambda lifecycle.