Stepwise assembly of initiation proteins at budding yeast replication origins in vitro.
The initiation of DNA replication in the budding yeast Saccharomyces cerevisiae occurs in two sequential and mutually exclusive steps. Prereplicative complexes (pre-RCs) containing origin recognition complex (ORC), Cdc6p, and the MCM2-7 proteins assemble only under conditions of low cyclin-dependent kinase (Cdk) activity during G(1), whereas origin activation is driven by the increase in Cdk activity at the end of G(1). As a first step toward the reconstitution of this two-step process in vitro, we describe a system in which extracts prepared from G(1)-arrested cells promote sequential assembly of ORC, Cdc6p, and MCM2-7 proteins onto exogenously added origin-containing DNA. This reaction requires an intact ARS consensus sequence and requires ATP for two distinct steps. Extracts from cells arrested in mitosis also can support the binding of ORC but are unable to load either Cdc6p or MCM2-7 proteins. This system should be useful for studying the mechanism and regulation of pre-RC assembly.
Seki
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Clare Hall Laboratories, Imperial Cancer Research Fund, South Mimms, EN6 3LD, United Kingdom.
Diffley
J F
JF
D000255:Adenosine Triphosphate / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002474:Cell-Free System; D002868:Chromosomal Proteins, Non-Histone; D004261:DNA Replication; D004271:DNA, Fungal; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D008938:Mitosis; D051738:Origin Recognition Complex; D018741:Replication Origin; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
C066503:CDC6 protein, S cerevisiae; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D051738:Origin Recognition Complex; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; C069199:MCM2 protein, S cerevisiae