Homologous Recombination: To Fork and Beyond

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Genome duplication is essential for cell division but is frequently threatened by DNA damage and lesions that stall replication forks.
• Cells employ DNA damage tolerance (DDT) mechanisms to bypass lesions, which can lead to the accumulation of single-stranded DNA (ssDNA) behind the replication fork.
• Homologous recombination (HR) is a critical pathway involved in both replication fork protection and the repair of ssDNA gaps.

Purpose of the Study:

• To review the current understanding of homologous recombination mechanisms operating at and behind replication forks in eukaryotes.
• To discuss the regulatory control of these HR mechanisms to prevent toxic recombination intermediates.
• To propose a unifying model for replication fork-associated recombination processes based on yeast studies.

Main Methods:

• Literature review of homologous recombination and DNA replication/damage tolerance mechanisms in eukaryotic cells.
• Analysis and synthesis of existing research findings, particularly from yeast models.
• Development of a conceptual model integrating recombination processes at the replication fork.

Main Results:

• Homologous recombination plays dual roles: protecting stalled replication forks from collapse and facilitating the repair of post-replicative ssDNA gaps.
• Regulation of HR is crucial to prevent aberrant recombination events that could compromise genome stability.
• Yeast studies provide a foundation for a unified model of dynamic, replication fork-associated recombination.

Conclusions:

• Homologous recombination is indispensable for maintaining genome integrity during DNA replication, especially under genotoxic stress.
• Understanding the precise control of HR at replication forks is key to preventing genomic instability.
• A unified model integrating HR functions at the replication fork offers a framework for future research in eukaryotes.