Interdependent nuclear accumulation of budding yeast Cdt1 and Mcm2–7 during G1 phase

Abstract

Cdt1 is essential for loading Mcm2–7 proteins into prereplicative complexes (pre-RCs) during replication licensing and has been found in organisms as diverse as fission yeast and humans. We have identified a homologue of Cdt1 in Saccharomyces cerevisiae, which is required for pre-RC assembly. We show that, like Mcm2–7p, Cdt1p accumulates in the nucleus during G1 phase and is excluded from the nucleus later in the cell cycle by cyclin dependent kinases (cdks). Cdt1p interacts with the Mcm2–7p complex, and the nuclear accumulation of these proteins during G1 is interdependent. This coregulation of Cdt1p and Mcm2–7p represents a novel level of pre-RC control.