Phosphorylation of Sld2 and Sld3 by cyclin-dependent kinases promotes DNA replication in budding yeast.
Cyclin-dependent kinases (CDKs) drive major cell cycle events including the initiation of chromosomal DNA replication. We identified two S phase CDK (S-CDK) phosphorylation sites in the budding yeast Sld3 protein that, together, are essential for DNA replication. Here we show that, when phosphorylated, these sites bind to the amino-terminal BRCT repeats of Dpb11. An Sld3-Dpb11 fusion construct bypasses the requirement for both Sld3 phosphorylation and the N-terminal BRCT repeats of Dpb11. Co-expression of this fusion with a phospho-mimicking mutant in a second essential CDK substrate, Sld2, promotes DNA replication in the absence of S-CDK. Therefore, Sld2 and Sld3 are the minimal set of S-CDK targets required for DNA replication. DNA replication in cells lacking G1 phase CDK (G1-CDK) required expression of the Cdc7 kinase regulatory subunit, Dbf4, as well as Sld2 and Sld3 bypass. Our results help to explain how G1- and S-CDKs promote DNA replication in yeast.
Zegerman
Philip
P
Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK.
Diffley
John F X
JF
D018797:Cell Cycle Proteins / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D004261:DNA Replication; D004271:DNA, Fungal / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000378:metabolism*; D016193:G1 Phase; D010766:Phosphorylation; D011485:Protein Binding; D016196:S Phase; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D004718:Saccharomycetales / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D020349:Surface Plasmon Resonance
D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; C097185:DPB11 protein, S cerevisiae; C115043:SLD2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C426020:Sld3 protein, S cerevisiae; D018844:Cyclin-Dependent Kinases