Nucleic Acids Research

Cdt1-binding protein GRWD1 is a novel histone-binding protein that facilitates MCM loading through its influence on chromatin architecture

Sugimoto, N., Maehara, K., Yoshida, K., Yasukouchi, S., Osano, S., Watanabe, S., Aizawa, M., Yugawa, T., Kiyono, T., Kurumizaka, H., Ohkawa, Y., Fujita, M..

Efficient pre-replication complex (pre-RC) formation on chromatin templates is crucial for the maintenance of genome integrity. However, the regulation of chromatin dynamics during this process has remained elusive. We found that a conserved protein, GRWD1 (glutamate-rich WD40 repeat containing 1), binds to two representative replication origins specifically during G1 phase in a CDC6- and Cdt1-dependent manner, and that depletion of GRWD1 reduces loading of MCM but not CDC6 and Cdt1. Furthermore, chromatin immunoprecipitation coupled with high-throughput sequencing (Seq) revealed significant genome-wide co-localization of GRWD1 with CDC6. We found that GRWD1 has histone-binding activity. To investigate the effect of GRWD1 on chromatin architecture, we used formaldehyde-assisted isolation of regulatory elements (FAIRE)-seq or FAIRE-quantitative PCR analyses, and the results suggest that GRWD1 regulates chromatin openness at specific chromatin locations. Taken together, these findings suggest that GRWD1 may be a novel histone-binding protein that regulates chromatin dynamics and MCM loading at replication origins.