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The structural mechanism of dimeric DONSON in replicative helicase activation
Milos A Cvetkovic1, Paolo Passaretti2, Agata Butryn1
1Macromolecular Machines Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
Molecular Cell
|October 11, 2023
Summary
Downstream neighbor of Son (DONSON) bridges double CMG complexes, reconfiguring MCM motors for DNA replication. DONSON mutations impair GINS/MCM interaction and DNA synthesis, impacting human cells and Xenopus egg extracts.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Replicative helicase CMG assembly is crucial for DNA replication initiation.
- While yeast CMG formation is understood, its mechanism in higher eukaryotes remains unclear.
- Metazoan DONSON delivers GINS to MCM, but its role in CMG assembly is unknown.
Purpose of the Study:
- To investigate the impact of DONSON on MCM double hexamer during CMG assembly in higher eukaryotes.
- To elucidate the structural mechanism of CMG formation mediated by DONSON.
Main Methods:
- Cryo-electron microscopy (cryo-EM) of proteins from Xenopus egg extracts.
- Analysis of DONSON dimerization and its effect on GINS and MCM interaction.
Main Results:
- Identified a double CMG complex bridged by a DONSON dimer in Xenopus extracts.
- DONSON tethering elements are essential for replication.
- DONSON reconfigures MCM motors within the double CMG complex.
- DONSON dimerization mutations disrupt GINS/MCM engagement and DNA synthesis.
Conclusions:
- DONSON plays a critical role in higher eukaryotic CMG helicase formation by bridging MCM double hexamers.
- DONSON's structural role is vital for DNA replication, and its dysfunction underlies certain human genetic disorders.
Keywords:
DNA replication initiationDONSONXenopus egg extractcryo-EMprimordial dwarfismreplicative helicaseMore Related Videos
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