8B8T

Open conformation of the complex of DNA ligase I on PCNA and DNA in the presence of ATP

Summary for 8B8T

• Entry DOI: 10.2210/pdb8b8t/pdb
• EMDB information: 14080 15921
• Descriptor: DNA ligase 1, Proliferating cell nuclear antigen (2 entities in total)
• Functional Keywords: dna, replication, complex, ligase, pcna, ligation, okazaki fragment maturation
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 4
• Total formula weight: 115044.85

Authors

Blair, K.,Tehseen, M.,Raducanu, V.S.,Shahid, T.,Lancey, C.,Cruehet, R.,Hamdan, S.,De Biasio, A. (deposition date: 2022-10-05, release date: 2023-01-11, Last modification date: 2025-07-09)

Primary citation

Blair, K.,Tehseen, M.,Raducanu, V.S.,Shahid, T.,Lancey, C.,Rashid, F.,Creuhet, R.,Hamdan, S.M.,De Biasio, A.
Mechanism of human Lig1 regulation by PCNA in Okazaki fragment sealing.
Nat Commun, 13:7833-7833, 2022

PubMed Abstract: During lagging strand synthesis, DNA Ligase 1 (Lig1) cooperates with the sliding clamp PCNA to seal the nicks between Okazaki fragments generated by Pol δ and Flap endonuclease 1 (FEN1). We present several cryo-EM structures combined with functional assays, showing that human Lig1 recruits PCNA to nicked DNA using two PCNA-interacting motifs (PIPs) located at its disordered N-terminus (PIP) and DNA binding domain (PIP). Once Lig1 and PCNA assemble as two-stack rings encircling DNA, PIP is released from PCNA and only PIP is required for ligation to facilitate the substrate handoff from FEN1. Consistently, we observed that PCNA forms a defined complex with FEN1 and nicked DNA, and it recruits Lig1 to an unoccupied monomer creating a toolbelt that drives the transfer of DNA to Lig1. Collectively, our results provide a structural model on how PCNA regulates FEN1 and Lig1 during Okazaki fragments maturation.

PubMed: 36539424
DOI: 10.1038/s41467-022-35475-z

Experimental method

ELECTRON MICROSCOPY (4.2 Å)