title: The replication initiation protein Sld2 regulates helicase assembly.
abstract: Assembly of the Cdc45-Mcm2-7-GINS (CMG) replicative helicase complex must be regulated to ensure that DNA unwinding is coupled with DNA synthesis. Sld2 is required for the initiation of DNA replication in budding yeast. We identified a mutant of Sld2, Sld2-m1,4, that is specifically defective in Mcm2-7 binding. When this sld2-m1,4 mutant is expressed, cells exhibit severe inhibition of DNA replication. Furthermore, the CMG complex assembles prematurely in G1 in mutant cells, but not wild-type cells. These data suggest that Sld2 binding to Mcm2-7 is essential to block the inappropriate formation of a CMG helicase complex in G1. We also study a mutant of Sld2 that is defective in binding DNA, sld2-DNA, and find that sld2-DNA cells exhibit no GINS-Mcm2-7 interaction. These data suggest that Sld2 association with DNA is required for CMG assembly in S phase.
authors.affiliation: From the Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32312.
authors.forename: Irina
authors.initials: I
authors.lastname: Bruck
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Kaplan
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication / Q000502:physiology*; D004271:DNA, Fungal / Q000096:biosynthesis* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D064168:Minichromosome Maintenance Complex Component 7 / Q000235:genetics / Q000378:metabolism; D064110:Minichromosome Maintenance Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D016196:S Phase / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C102209:CDC45 protein, S cerevisiae; D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C115043:SLD2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C069199:MCM2 protein, S cerevisiae; C491088:MCM7 protein, S cerevisiae; D064168:Minichromosome Maintenance Complex Component 7; D064110:Minichromosome Maintenance Proteins
keywords: CDK (Cyclin-dependent Kinase); Cell Cycle; DNA Helicase; DNA Replication; DNA-binding Protein