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Enzymatic switching for efficient and accurate translesion DNA replication.
Scott D McCulloch1, Robert J Kokoska, Olga Chilkova
1Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.
Nucleic Acids Research
|August 31, 2004
Summary
DNA polymerases switch to bypass thymine-thymine dimers, enabling accurate replication. This process involves DNA polymerase eta and replicative polymerases, suppressing mutagenesis and skin cancer.
Area of Science:
- Molecular Biology
- DNA Replication
- Biochemistry
Background:
- Cyclobutane pyrimidine dimers stall DNA replication by major replicative polymerases.
- Translesion synthesis (TLS) is crucial for bypassing DNA lesions.
- DNA polymerase eta (Pol eta) is known for its TLS capabilities.
Purpose of the Study:
- To investigate the enzymatic switching mechanism during DNA replication bypass of thymine-thymine (TT) dimers.
- To elucidate the roles of Saccharomyces cerevisiae Pol delta, Pol epsilon, and Pol eta in dimer bypass.
- To understand how accurate replication is restored after lesion bypass.
Main Methods:
- Utilized Saccharomyces cerevisiae DNA polymerases (Pol delta, Pol epsilon, Pol eta).
- Employed a series of matched and mismatched primer-templates mimicking TT dimer bypass.
- Analyzed substrate utilization patterns during enzymatic switching.
Main Results:
- Observed a complementary pattern of substrate use by different DNA polymerases.
- Demonstrated that localized TLS by Pol eta is followed by mismatch excision and polymerization.
- Indicated that this switching mechanism facilitates efficient and accurate TT dimer bypass.
Conclusions:
- Enzymatic switching involving Pol eta and replicative polymerases accounts for efficient TT dimer bypass.
- This mechanism suppresses sunlight-induced mutagenesis and skin cancer.
- The findings provide insights into maintaining genome stability during replication stress.