PXD080178

PXD080178 is an original dataset announced via ProteomeXchange.

Title	Mechanisms of MCM2-7 helicase activation and initial DNA melting at near base-pair resolution
Description	During eukaryotic DNA replication initiation, inactive MCM2-7 double-hexamers assembled at replication origins must be converted into two active CMG helicases, yet how this transition is coupled to origin DNA unwinding in vivo remains unclear. Here, we identify a DNA-bound intermediate with an extended genomic footprint that forms during helicase activation. Genome-wide mapping of initial strand separation reveals that DNA unwinding initiates near the N-terminal interface of opposing MCM2-7 hexamers. At these sites, the origin DNA exhibits a conserved AT-rich/GC-rich/AT-rich sequence architecture centred under the helicase complex, which is associated with an elevated DNA melting probability. We further show that restricting hexamer splitting delays release of the Cdc45-loading factor Sld3, demonstrating that mechanical transitions during helicase activation are tightly coupled to complex disassembly. Finally, we provide in vivo evidence that single-stranded DNA is ejected through a specialised DNA exit gate at the Mcm2/5 interface during helicase activation, which is dispensable for ongoing DNA synthesis. Together, these findings establish a mechanistic framework for how replication origins are remodelled to initiate DNA replication and reveal key intermediates and DNA transactions during helicase activation.
HostingRepository	PRIDE
AnnounceDate	2026-06-26
AnnouncementXML	Submission_2026-06-26_04:44:31.279.xml
DigitalObjectIdentifier
ReviewLevel	Peer-reviewed dataset
DatasetOrigin	Original dataset
RepositorySupport	Unsupported dataset by repository
PrimarySubmitter	Alex Montoya
SpeciesList	scientific name: Saccharomyces cerevisiae (Baker's yeast); NCBI TaxID: NEWT:4932;
ModificationList	acetylated residue; monohydroxylated residue
Instrument	Q Exactive

Revision	Datetime	Status	ChangeLog Entry
0	2026-06-25 08:37:42	ID requested
⏵ 1	2026-06-26 04:44:31	announced

Dataset with its publication pending

submitter keyword: ssDNA, helicase, unwinding, origins, DNA Replication, yeast, ChIP-Exo,MCM2-7, RPA, S-phase

Professor Christian Speck
contact affiliation	Head of the DNA Replication Research Group
contact email	chris.speck@imperial.ac.uk
lab head
Alex Montoya
contact affiliation	London Institute of Medical Sciences
contact email	proteomics@lms.mrc.ac.uk
dataset submitter

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PRIDE project URI

• PRIDE
  1. PXD080178
     1. Label: PRIDE project
     2. Name: Mechanisms of MCM2-7 helicase activation and initial DNA melting at near base-pair resolution