Dynamics of Cdk1 Substrate Specificity during the Cell Cycle

• Published in: Molecular cell Vol. 42; no. 5; pp. 610 - 623
• Main Authors: Kõivomägi, Mardo, Valk, Ervin, Venta, Rainis, Iofik, Anna, Lepiku, Martin, Morgan, David O., Loog, Mart
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10.06.2011; Cell Press
• Subjects: active sites; Amino Acid Motifs; Binding Sites; CDC2 Protein Kinase - chemistry; CDC2 Protein Kinase - metabolism; Cell Cycle; Consensus Sequence; cyclins; Hydrophobic and Hydrophilic Interactions; Models, Biological; phosphorylation; Saccharomyces cerevisiae; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - metabolism; Substrate Specificity; yeasts
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/j.molcel.2011.05.016

Cdk specificity is determined by the intrinsic selectivity of the active site and by substrate docking sites on the cyclin subunit. There is a long-standing debate about the relative importance of these factors in the timing of Cdk1 substrate phosphorylation. We analyzed major budding yeast cyclins (the G1/S-cyclin Cln2, S-cyclin Clb5, G2/M-cyclin Clb3, and M-cyclin Clb2) and found that the activity of Cdk1 toward the consensus motif increased gradually in the sequence Cln2-Clb5-Clb3-Clb2, in parallel with cell cycle progression. Further, we identified a docking element that compensates for the weak intrinsic specificity of Cln2 toward G1-specific targets. In addition, Cln2-Cdk1 showed distinct consensus site specificity, suggesting that cyclins do not merely activate Cdk1 but also modulate its active-site specificity. Finally, we identified several Cln2-, Clb3-, and Clb2-specific Cdk1 targets. We propose that robust timing and ordering of cell cycle events depend on gradual changes in the substrate specificity of Cdk1. ► Cyclins gradually raise the active-site specificity of Cdk1 during the cell cycle ► A novel substrate docking motif is specific for G1-cyclin-Cdk1 complexes ► G1 cyclin-Cdk1 shows distinct features of substrate site consensus specificity ► Several G1, G2, and M phase-specific Cdk1 targets exist in the cell