title: S-Cdk-dependent phosphorylation of Sld2 essential for chromosomal DNA replication in budding yeast.
abstract: Cyclin-dependent protein kinases (Cdks) in eukaryotic cells work as a key enzyme at various points in the cell cycle. At the onset of S phase, active S-phase Cdks (S-Cdks) are essential for chromosomal DNA replication. Although several replication proteins are phosphorylated in a Cdk-dependent manner, the biological effects of phosphorylation of these proteins on the activation of DNA replication have not been elucidated. Here we show that Sld2 (ref. 4) (also known as Drc1; ref. 5), one of the replication proteins of budding yeast (Saccharomyces cerevisiae), is phosphorylated in S phase in an S-Cdk-dependent manner, and mutant Sld2 lacking all the preferred Cdk phosphorylation sites (All-A) is defective in chromosomal DNA replication. Moreover, the complex that contains, at least, Sld2 and Dpb11 (ref. 6) (the Sld2-Dpb11 complex) is formed predominantly in S phase; the All-A protein is defective in this complex formation. Because this complex is suggested to be essential for chromosomal DNA replication, it seems likely that S-Cdk positively regulates formation of the Sld2-Dpb11 complex and, consequently, chromosomal DNA replication.
authors.affiliation: Division of Microbial Genetics, National Institute of Genetics, The Graduate University for Advanced Studies, Yata 1111, Mishima, Shizuoka 411-8540, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Masumoto
authors.forename: Sachiko
authors.initials: S
authors.lastname: Muramatsu
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Kamimura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Araki
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D015825:Chromosomes, Fungal; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D004261:DNA Replication; D004271:DNA, Fungal / Q000096:biosynthesis*; D005656:Fungal Proteins / Q000378:metabolism; D010766:Phosphorylation; D017354:Point Mutation; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D004718:Saccharomycetales / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D005656:Fungal Proteins; C115043:SLD2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C051655:Suc1 protein, S pombe; D018844:Cyclin-Dependent Kinases