EMD-28075
Structure of Lates calcarifer DNA polymerase theta polymerase domain with long duplex DNA, complex Ia
EMD-28075
Single-particle2.4 Å
Deposition: 08/09/2022Map released: 14/12/2022
Last modified: 19/06/2024
Sample Organism:
Lates calcarifer
Sample: Ternary complex of Lates calcarifer DNA polymerase Theta with duplex DNA and incoming nucleotide
Fitted models: 8ef9 (Avg. Q-score: 0.605)
Deposition Authors: Li C
,
Zhu H,
Sun J,
Gao Y
Sample: Ternary complex of Lates calcarifer DNA polymerase Theta with duplex DNA and incoming nucleotide
Fitted models: 8ef9 (Avg. Q-score: 0.605)
Deposition Authors: Li C
,
Zhu H,
Sun J,
Gao Y
Structural basis of DNA polymerase theta mediated DNA end joining.
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.
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.