Polθ reverse transcribes RNA and promotes RNA-templated DNA repair

Science Advances
Authors
Gurushankar Chandramouly1†, Jiemin Zhao2†, Shane McDevitt1†, Timur Rusanov1, Trung Hoang1, Nikita Borisonnik1, Taylor Treddinick1, Felicia Wednesday Lopezcolorado3, Tatiana Kent1, Labiba A. Siddique1, Joseph Mallon1, Jacklyn Huhn1, Zainab Shoda1, Ekaterina Kashkina1, Alessandra Brambati4, Jeremy M. Stark3, Xiaojiang S. Chen2, Richard T. Pomerantz
10-13-2021 Zoom
12:00pm
PST
Categories
Chemical Biology of RNA
Keywords
RNA
DNA Repair
reverse transcriptase
Speaker
Christopher Smith
Abstract

Genome-embedded ribonucleotides arrest replicative DNA polymerases (Pols) and cause DNA breaks. Whether

mammalian DNA repair Pols efficiently use template ribonucleotides and promote RNA-templated DNA repair

synthesis remains unknown. We find that human Polq reverse transcribes RNA, similar to retroviral reverse tran-

scriptases (RTs). Polq exhibits a significantly higher velocity and fidelity of deoxyribonucleotide incorporation on

RNA versus DNA. The 3.2-Å crystal structure of Polq on a DNA/RNA primer-template with bound deoxyribonucle-

otide reveals that the enzyme undergoes a major structural transformation within the thumb subdomain to

accommodate A-form DNA/RNA and forms multiple hydrogen bonds with template ribose 2′-hydroxyl groups like

retroviral RTs. Last, we find that Polq promotes RNA-templated DNA repair in mammalian cells. These findings

suggest that Polq was selected to accommodate template ribonucleotides during DNA repair.