The RecBC complex protects single-stranded DNA gaps during lesion bypass.

Area of Science:

• Molecular Biology
• Genetics
• DNA Repair

Background:

• DNA replication halts at unrepaired lesions, creating single-stranded DNA (ssDNA) gaps.
• These gaps are repaired via Translesion Synthesis (TLS) or Homology Directed Gap Repair (HDGR).

Purpose of the Study:

• To investigate a novel role for the RecBC complex in DNA lesion tolerance.
• To understand how RecBC protects nascent DNA during replication restart.

Main Methods:

• Genetic analysis of RecBC function in DNA lesion bypass.
• Investigating the interaction between RecBC, ExoI, and nascent DNA.

Main Results:

• RecBC protects nascent DNA from degradation by ExoI, independent of its catalytic activity and the RecD subunit.
• RecBC is crucial for efficient TLS and HDGR, particularly at strong blocking lesions.
• Loss of RecBC allows ExoI to degrade nascent DNA, impairing lesion tolerance.

Conclusions:

• RecBC has a non-canonical role in safeguarding nascent DNA during replication restart.
• This protective function is conserved across species, similar to BRCA2 in humans.
• RecBC is essential for maintaining genome integrity following DNA damage.