Cell cycle regulation has shaped replication origins in budding yeast.

ABSTRACT: Eukaryotic DNA replication initiates from genomic loci known as origins. At budding yeast origins like ARS1, a double hexamer (DH) of the MCM replicative helicase is assembled by origin recognition complex (ORC), Cdc6 and Cdt1 by sequential hexamer loading from two opposed ORC binding sites. Cyclin-dependent kinase (CDK) inhibits DH assembly, which prevents re-replication by restricting helicase loading to the G1 phase. Here, we show that an intrinsically disordered region (IDR) in the Orc2 subunit promotes interaction between ORC and the first loaded, closed-ring MCM hexamer (the MCM-ORC (MO) intermediate). CDK-dependent phosphorylation of this IDR blocks MO formation and DH assembly. We show that MO stabilizes ORC at lower-affinity binding sites required for second hexamer loading. Origi

SUBMITTER: Lim CT 

PROVIDER: S-EPMC12440816 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature