Watching a double strand break repair polymerase insert a pro-mutagenic oxidized nucleotide.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33824325.
- Also identified by DOI 10.1038/s41467-021-21354-6 and PMC identifier 8024293.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Oxidized dGTP (8-oxo-7,8-dihydro-2´-deoxyguanosine triphosphate, 8-oxodGTP) insertion by DNA polymerases strongly promotes cancer and human disease. How DNA polymerases discriminate against oxidized and undamaged nucleotides, especially in error-prone double strand break (DSB) repair, is poorly understood. High-resolution time-lapse X-ray crystallography snapshots of DSB repair polymerase μ undergoing DNA synthesis reveal that a third active site metal promotes insertion of oxidized and undamaged dGTP in the canonical anti-conformation opposite template cytosine. The product metal bridged O8 with product oxygens, and was not observed in the syn-conformation opposite template adenine (A<sub>t</sub>). Rotation of A<sub>t</sub> into the syn-conformation enabled undamaged dGTP misinsertion. Exploiting metal and substrate dynamics in a rigid active site allows 8-oxodGTP to circumvent polymerase fidelity safeguards to promote pro-mutagenic double strand break repair.
Medical subject headings
- DNA Breaks, Double-Stranded
- DNA Repair
- DNA-Directed DNA Polymerase
- Mutagenesis
- Nucleotides