A bacterial protein requirement for the bacteriophage lambda terminase reaction.

Area of Science:

• Molecular Biology
• Virology
• Biochemistry

Background:

• Bacteriophage lambda DNA replication involves the terminase enzyme.
• Terminase enzyme cleaves cohesive-end sites of lambda DNA.
• This cleavage requires a protein factor from E. coli.

Purpose of the Study:

• To isolate and characterize the protein factor required for lambda DNA cleavage.
• To investigate the role of this factor in the terminase reaction.
• To compare the factor's function with the known integration host factor (IHF).

Main Methods:

• Purification of a protein factor from E. coli extracts.
• Biochemical assays to test the factor's activity in lambda DNA cleavage.
• Comparison of the factor's activity with purified E. coli integration host factor (IHF).

Main Results:

• A heat-stable, basic protein factor, termed terminase host factor (THF), was isolated.
• THF has an approximate molecular weight of 22,000.
• E. coli integration host factor (IHF) efficiently substitutes for THF.
• THF is present and active in E. coli cells lacking or deficient in IHF.

Conclusions:

• Terminase host factor (THF) is essential for bacteriophage lambda DNA processing.
• While IHF can substitute for THF, THF is an independent factor.
• The presence of THF in IHF-deficient cells suggests distinct roles or regulatory mechanisms.