Structural basis of DNA polymerase θ mediated DNA end joining. Issue 1 (30th December 2022)

• Record Type: Journal Article
• Authors: Li, Chuxuan; Zhu, Hanwen; Jin, Shikai; Maksoud, Leora M; Jain, Nikhil; Sun, Ji; Gao, Yang
• Is Part Of: Nucleic acids research. Volume 51:Issue 1(2023)
• Page Start: 463
• Page End: 474
• Publication Date: 2022-12-30
• Subjects: Nucleic acids -- Periodicals; Molecular biology -- Periodicals; 572.805
• DOI: 10.1093/nar/gkac1201
• Languages: English
• ISSNs: 0305-1048

Abstract

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.