title: Sequential ATP hydrolysis by Cdc6 and ORC directs loading of the Mcm2-7 helicase.
abstract: Loading of the Mcm2-7 DNA replicative helicase onto origin-proximal DNA is a critical and tightly regulated event during the initiation of eukaryotic DNA replication. The resulting protein-DNA assembly is called the prereplicative complex (pre-RC), and its formation requires the origin recognition complex (ORC), Cdc6, Cdt1, and ATP. ATP hydrolysis by ORC is required for multiple rounds of Mcm2-7 loading. Here, we investigate the role of ATP hydrolysis by Cdc6 during pre-RC assembly. We find that Cdc6 is an ORC- and origin DNA-dependent ATPase that functions at a step preceding ATP hydrolysis by ORC. Inhibiting Cdc6 ATP hydrolysis stabilizes Cdt1 on origin DNA and prevents Mcm2-7 loading. In contrast, the initial association of Mcm2-7 with the other pre-RC components does not require ATP hydrolysis by Cdc6. Importantly, these coordinated yet distinct functions of ORC and Cdc6 ensure the correct temporal and spatial regulation of pre-RC formation.
authors.affiliation: Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: John C W
authors.initials: JC
authors.lastname: Randell
authors.forename: Jayson L
authors.initials: JL
authors.lastname: Bowers
authors.forename: Heather K
authors.initials: HK
authors.lastname: Rodríguez
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Bell
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism*; D000345:Affinity Labels / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D064168:Minichromosome Maintenance Complex Component 7; D008954:Models, Biological; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D051738:Origin Recognition Complex / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000345:Affinity Labels; C066503:CDC6 protein, S cerevisiae; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009687:Nuclear Proteins; D051738:Origin Recognition Complex; D029701:Saccharomyces cerevisiae Proteins; C499592:TAH11 protein, S cerevisiae; C022571:adenosine 5'-O-(3-thiotriphosphate); D000255:Adenosine Triphosphate; C069199:MCM2 protein, S cerevisiae; C491088:MCM7 protein, S cerevisiae; D064168:Minichromosome Maintenance Complex Component 7