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Mec1 is one of multiple kinases that prime the Mcm2-7 helicase for phosphorylation by Cdc7.

Molecular cell | Nov 12, 2010

http://www.ncbi.nlm.nih.gov/pubmed/21070963

Activation of the eukaryotic replicative DNA helicase, the Mcm2-7 complex, requires phosphorylation by Cdc7/Dbf4 (Dbf4-dependent kinase or DDK), which, in turn, depends on prior phosphorylation of Mcm2-7 by an unknown kinase (or kinases). We identified DDK phosphorylation sites on Mcm4 and Mcm6 and found that phosphorylation of either subunit suffices for cell proliferation. Importantly, prior phosphorylation of either S/T-P or S/T-Q motifs on these subunits is required for DDK phosphorylation of Mcm2-7 and for normal S phase passage. Phosphomimetic mutations of DDK target sites bypass both DDK function and mutation of the priming phosphorylation sites. Mrc1 facilitates Mec1 phosphorylation of the S/T-Q motifs of chromatin-bound Mcm2-7 during S phase to activate replication. Genetic interactions between priming site mutations and MRC1 or TOF1 deletion support a role for these modifications in replication fork stability. These findings identify regulatory mechanisms that modulate origin firing and replication fork assembly during cell cycle progression.

Pubmed ID: 21070963 RIS Download

Mesh terms: Amino Acid Sequence | Amino Acids | Cell Cycle | Cell Cycle Proteins | Chromatin | Chromosomal Proteins, Non-Histone | DNA-Binding Proteins | Intracellular Signaling Peptides and Proteins | Minichromosome Maintenance Complex Component 7 | Models, Biological | Molecular Sequence Data | Mutation | Nuclear Proteins | Phenotype | Phosphorylation | Protein-Serine-Threonine Kinases | Saccharomyces cerevisiae | Saccharomyces cerevisiae Proteins

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