EMD-29351
Cryo-EM structure of S. cerevisiae DNA polymerase alpha-primase complex in the post RNA handoff state
EMD-29351
Single-particle4.8 Å
Deposition: 30/12/2022Map released: 31/05/2023
Last modified: 13/03/2024
Sample Organism:
Saccharomyces cerevisiae,
synthetic construct
Sample: DNA polymerase alpha/primase complex
Fitted models: 8foj (Avg. Q-score: 0.336)
Deposition Authors: Yuan Z
,
Georgescu R,
Li H ,
O'Donnell M
Sample: DNA polymerase alpha/primase complex
Fitted models: 8foj (Avg. Q-score: 0.336)
Deposition Authors: Yuan Z
,
Georgescu R,
Li H ,
O'Donnell M
Molecular choreography of primer synthesis by the eukaryotic Pol alpha-primase.
Abstract:
The eukaryotic polymerase α (Pol α) synthesizes an RNA-DNA hybrid primer of 20-30 nucleotides. Pol α is composed of Pol1, Pol12, Primase 1 (Pri1), and Pri2. Pol1 and Pri1 contain the DNA polymerase and RNA primase activities, respectively. It has been unclear how Pol α hands over an RNA primer from Pri1 to Pol1 for DNA primer extension, and how the primer length is defined. Here we report the cryo-EM analysis of yeast Pol α in the apo, primer initiation, primer elongation, RNA primer hand-off from Pri1 to Pol1, and DNA extension states, revealing a series of very large movements. We reveal a critical point at which Pol1-core moves to take over the 3'-end of the RNA from Pri1. DNA extension is limited by a spiral motion of Pol1-core. Since both Pri1 and Pol1-core are flexibly attached to a stable platform, primer growth produces stress that limits the primer length.
The eukaryotic polymerase α (Pol α) synthesizes an RNA-DNA hybrid primer of 20-30 nucleotides. Pol α is composed of Pol1, Pol12, Primase 1 (Pri1), and Pri2. Pol1 and Pri1 contain the DNA polymerase and RNA primase activities, respectively. It has been unclear how Pol α hands over an RNA primer from Pri1 to Pol1 for DNA primer extension, and how the primer length is defined. Here we report the cryo-EM analysis of yeast Pol α in the apo, primer initiation, primer elongation, RNA primer hand-off from Pri1 to Pol1, and DNA extension states, revealing a series of very large movements. We reveal a critical point at which Pol1-core moves to take over the 3'-end of the RNA from Pri1. DNA extension is limited by a spiral motion of Pol1-core. Since both Pri1 and Pol1-core are flexibly attached to a stable platform, primer growth produces stress that limits the primer length.