DONSON is required for CMG helicase assembly in the mammalian cell cycle

TY - JOUR

T1 - DONSON is required for CMG helicase assembly in the mammalian cell cycle

AU - Evrin, Cecile

AU - Alvarez, Vanesa

AU - Ainsworth, Johanna

AU - Fujisawa, Ryo

AU - Alabert, Constance

AU - Labib, Karim P. M.

N1 - Copyright:© 2023 The Authors. Published under the terms of the CC BY 4.0 license.

PY - 2023/11/6

Y1 - 2023/11/6

N2 - DONSON is one of 13 genes mutated in a form of primordial microcephalic dwarfism known as Meier-Gorlin Syndrome. The other 12 encode components of the CDC45-MCM-GINS helicase, around which the eukaryotic replisome forms, or are factors required for helicase assembly during DNA replication initiation. A role for DONSON in CDC45-MCM-GINS assembly was unanticipated, since DNA replication initiation can be reconstituted in vitro with purified proteins from budding yeast, which lacks DONSON. Using mouse embryonic stem cells as a model for the mammalian helicase, we show that DONSON binds directly but transiently to CDC45-MCM-GINS during S-phase and is essential for chromosome duplication. Rapid depletion of DONSON leads to the disappearance of the CDC45-MCM-GINS helicase from S-phase cells and our data indicate that DONSON is dispensable for loading of the MCM2-7 helicase core onto chromatin during G1-phase, but instead is essential for CDC45-MCM-GINS assembly during S-phase. These data identify DONSON as a missing link in our understanding of mammalian chromosome duplication and provide a molecular explanation for why mutations in human DONSON are associated with Meier-Gorlin syndrome.

AB - DONSON is one of 13 genes mutated in a form of primordial microcephalic dwarfism known as Meier-Gorlin Syndrome. The other 12 encode components of the CDC45-MCM-GINS helicase, around which the eukaryotic replisome forms, or are factors required for helicase assembly during DNA replication initiation. A role for DONSON in CDC45-MCM-GINS assembly was unanticipated, since DNA replication initiation can be reconstituted in vitro with purified proteins from budding yeast, which lacks DONSON. Using mouse embryonic stem cells as a model for the mammalian helicase, we show that DONSON binds directly but transiently to CDC45-MCM-GINS during S-phase and is essential for chromosome duplication. Rapid depletion of DONSON leads to the disappearance of the CDC45-MCM-GINS helicase from S-phase cells and our data indicate that DONSON is dispensable for loading of the MCM2-7 helicase core onto chromatin during G1-phase, but instead is essential for CDC45-MCM-GINS assembly during S-phase. These data identify DONSON as a missing link in our understanding of mammalian chromosome duplication and provide a molecular explanation for why mutations in human DONSON are associated with Meier-Gorlin syndrome.

KW - CMG helicase

KW - DNA replication

KW - DONSON

KW - Meier-Gorlin syndrome

KW - initiation

UR - https://www.scopus.com/pages/publications/85173486895

U2 - 10.15252/embr.202357677

DO - 10.15252/embr.202357677

M3 - Article

C2 - 37781960

SN - 1469-221X

VL - 24

SP - 1

EP - 11

JO - EMBO Reports

JF - EMBO Reports

IS - 11

M1 - e57677

ER -