Assembling bacteriophage T7 leading-strand replisome for structural investigation

Area of Science:

• Molecular Biology
• Structural Biology
• Genetics

Background:

• The leading-strand replisome, comprising replicative helicase and polymerase, is crucial for DNA unwinding and synthesis during replication.
• Uncoupling of these enzymes leads to replication stress, errors, and genomic instability.
• Structural studies of large, dynamic replisome complexes are challenging.

Purpose of the Study:

• To determine the structure of a coupled helicase-polymerase replisome complex.
• To establish protocols for preparing and characterizing such complexes.
• To provide a model system for investigating complex replisomes.

Main Methods:

• Reconstitution of the bacteriophage T7 replisome complex.
• Structural determination of the replisome on a DNA fork substrate.
• Characterization of the coupled helicase-polymerase activity.

Main Results:

• The first structure of a coupled leading-strand replisome complex was determined using the bacteriophage T7 system.
• Protocols for preparing and characterizing the T7 replisome were established.
• The study provides a foundational model for understanding replisome dynamics and structure.

Conclusions:

• The determined structure offers insights into the coordinated function of helicase and polymerase in DNA replication.
• The established methods can be adapted for structural studies of more complex eukaryotic replisomes.
• This work advances our understanding of genome stability mechanisms and potential therapeutic targets for replication stress.