Efficient Initiation of DNA Replication in Eukaryotes Requires Dpb11/TopBP1-GINS Interaction

Abstract

Dpb11/Cut5/TopBP1 is evolutionarily conserved and is essential for the initiation of DNA replication in eukaryotes. The Dpb11 of the budding yeast Saccharomyces cerevisiae has four BRCT domains (BRCT1 to -4). The N-terminal pair (BRCT1 and -2) and the C-terminal pair (BRCT3 and -4) bind to cyclin-dependent kinase (CDK)-phosphorylated Sld3 and Sld2, respectively. These phosphorylation-dependent interactions trigger the initiation of DNA replication. BRCT1 and -2 and BRCT3 and -4 of Dpb11 are separated by a short stretch of ∼100 amino acids. It is unknown whether this inter-BRCT region functions in DNA replication. Here, we showed that the inter-BRCT region is a GINS interaction domain that is essential for cell growth and that mutations in this domain cause replication defects in budding yeast. We found the corresponding region in the vertebrate ortholog, TopBP1, and showed that the corresponding region also interacts with GINS and is required for efficient DNA replication. We propose that the inter-BRCT region of Dpb11 is a functionally conserved GINS interaction domain that is important for the initiation of DNA replication in eukaryotes.

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at http://dx.doi.org/10.1128/MCB.00431-13.

ACKNOWLEDGMENTS

We thank M. Yagura, S. Endo, H. Oizumi, and Y. Tanaka for technical help and discussions.

This study was partly supported by grants to Y. Kubota and S. Tanaka from the Ministry of Education, Culture, Sports, Science and Technology, Japan.