PCNA Deubiquitylases Control DNA Damage Bypass at Replication Forks

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• DNA damage tolerance is crucial for cell survival, employing translesion synthesis and template switching to bypass lesions.
• Both pathways depend on the ubiquitylation of proliferating-cell nuclear antigen (PCNA) at lysine 164.
• These tolerance mechanisms were thought to operate independently of DNA replication.

Purpose of the Study:

• To investigate the roles of Ubp10 and Ubp12 ubiquitin proteases in PCNA deubiquitylation.
• To determine how these proteases modulate DNA damage tolerance pathways at replication forks.
• To elucidate the mechanism by which PCNA deubiquitylation influences lesion bypass and replication fidelity.

Main Methods:

• Investigated the cooperative deubiquitylation of PCNA by Ubp10 and Ubp12.
• Analyzed the association of Ubp10 and Ubp12 with replication forks.
• Assessed the impact of these proteases on translesion polymerase recruitment and template switching events.

Main Results:

• Ubp10 and Ubp12 exhibit distinct activities on PCNA-linked ubiquitin chains, cooperating in deubiquitylation.
• These proteases associate with replication forks, with Ubp10's localization dependent on lagging-strand PCNA.
• Ubp10 and Ubp12 were found to downregulate translesion polymerase recruitment and template switching at nascent strands.

Conclusions:

• PCNA^K164 deubiquitylation is a key regulator of lesion bypass during DNA replication.
• This process allows for strand-differential pathway choices in DNA damage tolerance.
• Damage tolerance is regulated at replication forks to limit bypass extension and maintain chromosome replication rates.