Deegan, Tom D Yeeles, Joseph TP Diffley, John FX Phosphopeptide binding by Sld3 links Dbf4-dependent kinase to MCM replicative helicase activation The initiation of eukaryotic DNA replication requires the assembly of active CMG (Cdc45-MCM-GINS) helicases at replication origins by a set of conserved and essential firing factors. This process is controlled during the cell cycle by cyclin-dependent kinase (CDK) and Dbf4-dependent kinase (DDK), and in response to DNA damage by the checkpoint kinase Rad53/Chk1. Here we show that Sld3, previously shown to be an essential CDK and Rad53 substrate, is recruited to the inactive MCM double hexamer in a DDK-dependent manner. Sld3 binds specifically to DDK-phosphorylated peptides from two MCM subunits (Mcm4, 6) and then recruits Cdc45. MCM mutants that cannot bind Sld3 or Sld3 mutants that cannot bind phospho-MCM or Cdc45 do not support replication. Moreover, phosphomimicking mutants in Mcm4 and Mcm6 bind Sld3 without DDK and facilitate DDK-independent replication. Thus, Sld3 is an essential "reader" of DDK phosphorylation, integrating signals from three distinct protein kinase pathways to coordinate DNA replication during S phase. DDK;DNA replication initiation;Sld3;Cell Cycle Proteins;DNA Replication;DNA-Binding Proteins;Minichromosome Maintenance Complex Component 4;Minichromosome Maintenance Complex Component 6;Nuclear Proteins;Phosphopeptides;Protein Binding;Protein-Serine-Threonine Kinases;Replication Origin;Saccharomyces cerevisiae;Saccharomyces cerevisiae Proteins;Diffley FC001066;PC-ack;FERM-ack;Developmental Biology;06 Biological Sciences;08 Information and Computing Sciences;11 Medical and Health Sciences 2020-07-17
    https://crick.figshare.com/articles/journal_contribution/Phosphopeptide_binding_by_Sld3_links_Dbf4-dependent_kinase_to_MCM_replicative_helicase_activation/12662138