8Q6O

X. laevis CMG dimer bound to dimeric DONSON - without ATPase

Summary for 8Q6O

• Entry DOI: 10.2210/pdb8q6o/pdb
• EMDB information: 18191
• Descriptor: DNA replication licensing factor mcm2, Cell division control protein 45 homolog, DNA replication complex GINS protein SLD5, ... (13 entities in total)
• Functional Keywords: dna replication initiation, xenopus egg extract, primordial dwarfism, replicative helicase, genome stability, replication
• Biological source: Xenopus laevis (African clawed frog); More
• Total number of polymer chains: 24
• Total formula weight: 1538548.24

Authors

Butryn, A.,Cvetkovic, M.A.,Costa, A. (deposition date: 2023-08-14, release date: 2023-10-18, Last modification date: 2023-11-29)

Primary citation

Cvetkovic, M.A.,Passaretti, P.,Butryn, A.,Reynolds-Winczura, A.,Kingsley, G.,Skagia, A.,Fernandez-Cuesta, C.,Poovathumkadavil, D.,George, R.,Chauhan, A.S.,Jhujh, S.S.,Stewart, G.S.,Gambus, A.,Costa, A.
The structural mechanism of dimeric DONSON in replicative helicase activation.
Mol.Cell, 83:4017-, 2023

PubMed Abstract: The MCM motor of the replicative helicase is loaded onto origin DNA as an inactive double hexamer before replication initiation. Recruitment of activators GINS and Cdc45 upon S-phase transition promotes the assembly of two active CMG helicases. Although work with yeast established the mechanism for origin activation, how CMG is formed in higher eukaryotes is poorly understood. Metazoan Downstream neighbor of Son (DONSON) has recently been shown to deliver GINS to MCM during CMG assembly. What impact this has on the MCM double hexamer is unknown. Here, we used cryoelectron microscopy (cryo-EM) on proteins isolated from replicating Xenopus egg extracts to identify a double CMG complex bridged by a DONSON dimer. We find that tethering elements mediating complex formation are essential for replication. DONSON reconfigures the MCM motors in the double CMG, and primordial dwarfism patients' mutations disrupting DONSON dimerization affect GINS and MCM engagement in human cells and DNA synthesis in Xenopus egg extracts.

PubMed: 37820732
DOI: 10.1016/j.molcel.2023.09.029

Experimental method

ELECTRON MICROSCOPY (3.14 Å)