Molecular basis for PrimPol recruitment to replication forks by RPA.

Area of Science:

• Molecular Biology
• Cellular Biology
• Biochemistry

Background:

• DNA replication machinery can stall due to DNA damage or secondary structures.
• Cells employ tolerance mechanisms, including translesion synthesis (TLS) polymerases and primase-polymerase (PrimPol), to ensure genome duplication.
• PrimPol is a key enzyme that bypasses DNA damage via TLS and repriming replication.

Purpose of the Study:

• To elucidate the molecular mechanism of PrimPol recruitment to stalled replication forks.
• To identify the interaction partners and motifs involved in PrimPol's function.
• To understand how PrimPol facilitates replication restart.

Main Methods:

• Biophysical techniques
• Crystallographic approaches
• In vivo recruitment assays
• Biochemical analyses

Main Results:

• PrimPol interacts with Replication Protein A (RPA) for recruitment to stalled forks.
• Two RPA-binding motifs were identified in PrimPol, with specific residues crucial for interaction.
• One motif is essential for in vivo recruitment of PrimPol to stalled replication forks.
• RPA binding stimulates PrimPol's primase activity.

Conclusions:

• RPA is a critical factor for recruiting PrimPol to stalled replication forks.
• The identified RPA-binding motifs mediate PrimPol's function in replication restart.
• These findings offer molecular insights into PrimPol's role in maintaining genome stability.