Mcm10 regulates DNA replication elongation by stimulating the CMG replicative helicase

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• DNA replication initiation is a critical process in eukaryotes.
• The Mcm2-7 helicase complex requires activation by Cdc45 and GINS (CMG complex).
• Mcm10 protein's role in initial DNA unwinding is not fully understood.

Purpose of the Study:

• To elucidate the mechanism by which Mcm10 drives initial DNA unwinding.
• To investigate Mcm10's broader functions in DNA replication.
• To propose a new model for Mcm10's role in CMG complex activation.

Main Methods:

• Site-directed mutagenesis of Mcm2 to expose a conserved motif.
• Analysis of conditional-lethal MCM10 mutant cell growth.
• In vivo and in vitro assays for DNA unwinding and replication elongation.
• Characterization of a lethal MCM10 allele.

Main Results:

• Mcm10 binds a conserved motif on Mcm2, which, when exposed by mutations, restores cell growth.
• Mcm10 stimulates initial DNA unwinding and stabilizes CMG complex association.
• Mcm10 enhances replication elongation both in vivo and in vitro.
• A lethal Mcm10 allele shows defects in replication elongation and CMG binding despite promoting unwinding.

Conclusions:

• Mcm10's function extends beyond initiating DNA unwinding.
• Mcm10 acts as an activator of the CMG complex throughout DNA replication.
• Findings suggest a revised model for Mcm10's essential role in eukaryotic DNA replication.