Multisite SUMOylation restrains DNA polymerase η interactions with DNA damage sites

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Translesion DNA synthesis (TLS) is crucial for bypassing DNA lesions during replication.
• Low-fidelity TLS polymerases, like DNA polymerase η (Pol η), must be tightly regulated to prevent mutagenesis.
• Pol η recruitment to DNA damage sites involves monoubiquitylated PCNA.

Purpose of the Study:

• To investigate the role of SUMO modification in regulating Pol η activity at DNA damage sites.
• To identify factors involved in limiting Pol η interaction with damaged DNA.

Main Methods:

• Microscopy-based RNAi screen in human cells.
• Proteomic profiling to identify SUMOylation sites on Pol η.
• Analysis of protein interactions and cellular localization.

Main Results:

• Identified the SUMO modification pathway as a key regulator of Pol η localization.
• Demonstrated that PIAS1-dependent polySUMOylation of Pol η is triggered by association with monoubiquitylated PCNA.
• Showed that SUMOylation targets Pol η for displacement from DNA damage sites by STUbL.

Conclusions:

• A SUMO-driven feedback mechanism curtails Pol η interaction with PCNA at damaged DNA.
• This regulation is essential for preventing harmful mutagenesis during TLS.
• SUMOylation acts as an intrinsic control of TLS fidelity.