Exploring Novel SPEEDY-CDK Interactions: Expanding the Cell Cycle Regulatory Network

The intricate regulation of the cell cycle is crucial for normal cellular function, with dysregulation often leading to diseases such as cancer. While cyclin-dependent kinases (CDKs) are well-established regulators of cell cycle progression, the SPEEDY/RINGO family has emerged as an atypical activator of CDKs. To date, interactions have been identified only between a few SPEEDY proteins and CDK1/CDK2. However, the CDK family comprises more than 20 members, while the SPEEDY family includes nearly a dozen members, most of which remain unstudied. This study aims to elucidate the interactions between different SPEEDY family members and CDKs using an integrated bioinformatics and experimental approach. We employ protein-protein docking simulations and interface analysis to predict potential binding pairs. To validate our computational predictions, we perform biochemical testing including pull-down assays and co-expression studies. Furthermore, we use Isothermal Titration Calorimetry (ITC) to quantitatively measure the thermodynamic properties of these interactions, including binding affinity, stoichiometry, and enthalpy. Our findings reveal novel potential binding pairs between SPEEDY and CDK family members, highlighting the functional role of underexplored SPEEDY family members in cell cycle regulation. This comprehensive approach provides new perspectives on the complex interplay between these families in cell cycle control. Our results offer valuable insights into cell cycle regulation mechanisms and potentially uncover new drug targets for cancer therapeutics.