Year: 2022
Type: article
Abstract: DNA polymerase θ (Pol θ) plays an essential role in the microhomology-mediated end joining (MMEJ) pathway for repairing DNA double-strand breaks. However, the mechanisms by which Pol θ recognizes microhomologous DNA ends and performs low-fidelity DNA synthesis remain unclear. Here, we present cryo-electron microscope structures of the polymerase domain of Lates calcarifer Pol θ with long and short duplex DNA at up to 2.4 Å resolution. Interestingly, Pol θ binds to long and short DNA substrates similarly, with extensive interactions around the active site. Moreover, Pol θ shares a similar active site as high-fidelity A-family polymerases with its finger domain well-closed but differs in having hydrophilic residues surrounding the nascent base pair. Computational simulations and mutagenesis studies suggest that the unique insertion loops of Pol θ help to stabilize short DNA binding and assemble the active site for MMEJ repair. Taken together, our results illustrate the structural basis of Pol θ-mediated MMEJ.
Source: Nucleic Acids Research
DOI: 10.1093/nar/gkac1201
Authors: Chuxuan Li, Hanwen Zhu, Shikai Jin, Leora M Maksoud, Nikhil Jain, Ji Sun, Yang Gao
Language: English
Topic: DNA Repair Mechanisms
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,876
Awards: G119055551, Structural and Pharmacological Study of the KCNQ1/KCNE1 Potassium Channel Complex, G4879814465, Structure and mechanism of DNA polymerase theta in microhomology-mediated end joining and UV-lesion bypass, Recruitment of First-Time, Tenure-Track Faculty Members, Center for Theoretical Biological Physics, Structural and Pharmacological Study of the KCNQ1/KCNE1 Potassium Channel Complex, G9000306333
OpenAlex ID: W4313312330