Rapid assembly of the bacteriophage T4 core replication complex on a linear primer/template construct

Area of Science:

• Molecular Biology
• Biochemistry
• Virology

Background:

• Bacteriophage T4 DNA replication requires a multi-protein core complex.
• This complex includes T4 DNA polymerase, 32 protein, and accessory proteins 44/62 and 45.
• Efficient assembly of this complex on primed DNA substrates is essential for replication.

Purpose of the Study:

• To demonstrate the successful assembly of the T4 core replication complex on a short linear primer/template system.
• To investigate the role of DNA end modifications in facilitating complex assembly.
• To determine the conditions and kinetics of core complex formation.

Main Methods:

• Utilized a short linear primer/template DNA system with biotin moieties at the template strand ends.
• Incorporated streptavidin molecules to bind these biotin moieties, effectively blocking DNA ends.
• Assembled the T4 DNA polymerase, 32 protein, and accessory proteins 44/62 and 45 on the modified substrate.

Main Results:

• Achieved successful assembly of the T4 core replication complex at physiological accessory protein concentrations.
• Demonstrated that streptavidin-bound ends prevent accessory protein translocation and dissociation, stabilizing the complex.
• Confirmed that ATP and both accessory proteins 44/62 and 45 are required for assembly, with completion in approximately 2 seconds.

Conclusions:

• End-blocking with streptavidin is a key strategy for achieving stable assembly of the T4 DNA replication core complex.
• This method allows for efficient complex formation on short, linear DNA substrates.
• The findings provide insights into the regulation of bacteriophage DNA replication initiation.