Efficient initiation of DNA replication in eukaryotes requires Dpb11/TopBP1-GINS interaction

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• Dpb11/Cut5/TopBP1 is a conserved protein essential for eukaryotic DNA replication initiation.
• It possesses four BRCT domains involved in binding to replication factors Sld3 and Sld2.
• The function of the region separating the N-terminal and C-terminal BRCT domains was previously unknown.

Purpose of the Study:

• To investigate the role of the inter-BRCT region of Dpb11 in DNA replication.
• To determine if this region interacts with other proteins involved in replication.
• To assess the evolutionary conservation and functional significance of this region.

Main Methods:

• Site-directed mutagenesis to create mutations in the inter-BRCT region of Dpb11.
• Yeast growth assays to assess the impact of mutations on cell viability.
• Co-immunoprecipitation assays to detect protein-protein interactions between Dpb11 and GINS.
• Analysis of homologous regions in the vertebrate ortholog TopBP1.

Main Results:

• The inter-BRCT region of Dpb11 was identified as a GINS interaction domain.
• Mutations in this domain led to essential cell growth defects and replication defects in budding yeast.
• The corresponding region in vertebrate TopBP1 also interacts with GINS and is required for efficient DNA replication.

Conclusions:

• The inter-BRCT region of Dpb11 is a functionally conserved GINS interaction domain.
• This domain plays a critical role in the initiation of DNA replication in eukaryotes.
• The findings highlight a conserved mechanism for regulating DNA replication initiation across species.