Related Experiment Video
Updated: Jul 18, 2026

Determination of S-Phase Duration Using 5-Ethynyl-2'-deoxyuridine Incorporation in Saccharomyces cerevisiae
Published on: October 21, 2022
Phosphorylation of Sld2 and Sld3 by cyclin-dependent kinases promotes DNA replication in budding yeast
Philip Zegerman1, John F X Diffley
1Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK.
Abstract:
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.
Related Concept Videos
S-Cdk Initiates DNA Replication
Two states at the origin of replication
In eukaryotes, the initiation of replication occurs at many sites on the chromosomes, called the origins of replication.
S-Cdk Initiates DNA Replication
Two states at the origin of replication
In eukaryotes, the initiation of replication occurs at many sites on the chromosomes, called the origins of replication.
Inhibition of Cdk Activity
Positive Regulator Molecules
Positive Regulator Molecules
DNA Damage can Stall the Cell Cycle

