Werner syndrome protein interacts functionally with translesion DNA polymerases

Area of Science:

• Genetics
• Molecular Biology
• Biochemistry

Background:

• Werner syndrome (WS) is a premature aging disorder linked to mutations in the WRN gene.
• The WRN protein possesses DNA helicase and exonuclease activities crucial for genomic stability.
• Translesion synthesis (TLS) DNA polymerases are essential for bypassing DNA replication-blocking lesions.

Purpose of the Study:

• To investigate the functional interaction between the Werner syndrome protein (WRN) and TLS DNA polymerases.
• To elucidate the role of this interaction in DNA replication and genomic maintenance.

Main Methods:

• In vitro biochemical assays using purified WRN and TLS DNA polymerases (Poleta, Polkappa, Poliota).
• Analysis of WRN's effect on TLS polymerase extension activity and pausing at DNA lesions.
• In vivo studies using cell imaging to observe WRN and Poleta localization after UVC irradiation.

Main Results:

• WRN significantly stimulates the extension activity of TLS DNA polymerases on both normal and damaged DNA templates.
• WRN alleviates pausing of TLS polymerases at stalling lesions by increasing the reaction's V(max).
• WRN accelerates nucleotide incorporation by Poleta, leading to increased mutagenesis; WRN and Poleta colocalize at replication foci post-UVC exposure.

Conclusions:

• A functional interaction exists between WRN and TLS DNA polymerases, facilitating replication fork progression.
• This interaction may enhance DNA replication fidelity at the cost of increased mutagenesis, potentially preventing harmful chromosomal rearrangements.
• The findings offer insights into Werner syndrome pathogenesis and DNA repair mechanisms.