8V6G

DNA initiation complex (configuration 1) of Xenopus laevis DNA polymerase alpha-primase

Summary for 8V6G

• Entry DOI: 10.2210/pdb8v6g/pdb
• EMDB information: 42990
• Descriptor: DNA polymerase alpha catalytic subunit, IRON/SULFUR CLUSTER, DNA polymerase alpha subunit B, ... (10 entities in total)
• Functional Keywords: primase, dna polymerase, chimeric rna-dna primer, rna/dna hybrid, dna replication, dna synthesis, replication, transferase-dna-rna complex, transferase
• Biological source: Xenopus laevis (African clawed frog); More
• Total number of polymer chains: 6
• Total formula weight: 324796.16

Authors

Mullins, E.A.,Durie, C.L.,Ohi, M.D.,Chazin, W.J.,Eichman, B.F. (deposition date: 2023-12-01, release date: 2023-12-20, Last modification date: 2024-05-29)

Primary citation

Mullins, E.A.,Salay, L.E.,Durie, C.L.,Bradley, N.P.,Jackman, J.E.,Ohi, M.D.,Chazin, W.J.,Eichman, B.F.
A mechanistic model of primer synthesis from catalytic structures of DNA polymerase alpha-primase.
Nat.Struct.Mol.Biol., 31:777-790, 2024

PubMed Abstract: The mechanism by which polymerase α-primase (polα-primase) synthesizes chimeric RNA-DNA primers of defined length and composition, necessary for replication fidelity and genome stability, is unknown. Here, we report cryo-EM structures of Xenopus laevis polα-primase in complex with primed templates representing various stages of DNA synthesis. Our data show how interaction of the primase regulatory subunit with the primer 5' end facilitates handoff of the primer to polα and increases polα processivity, thereby regulating both RNA and DNA composition. The structures detail how flexibility within the heterotetramer enables synthesis across two active sites and provide evidence that termination of DNA synthesis is facilitated by reduction of polα and primase affinities for the varied conformations along the chimeric primer-template duplex. Together, these findings elucidate a critical catalytic step in replication initiation and provide a comprehensive model for primer synthesis by polα-primase.

PubMed: 38491139
DOI: 10.1038/s41594-024-01227-4

Experimental method

ELECTRON MICROSCOPY (11.16 Å)