Many regulatory protein-protein interactions depend on Short Linear Motifs (SLiMs). In the cell cycle, cyclin-CDKs recognize SLiMs to control substrate recruitment and phosphorylation timing. Here, we measure the relative binding strength of ~100,000 peptides to 11 human cyclins from five families (D, E, A, B, and F). Using a quantitative intracellular binding assay and large-scale tiled peptide screening, we identify multiple non-canonical binders unveiling a broader repertoire of cyclin docking motif types. Cryo-electron microscopy and saturation mutagenesis studies reveal distinct binding modes and sequence features governing motif recognition, binding strength, and cyclin preference. Docking motifs vary from highly selective to pan-cyclin, thereby fine-tuning the timing of CDK phosphorylation during cell cycle. Overall, these findings provide insights into the rules encoding specificity and affinity of SLiM-mediated interactions and offer a framework for understanding motif-driven protein networks across the proteome. Many protein–protein interactions depend on Short Linear Motifs (SLiMs). In this study, the authors use large-scale binding assays, deep mutational scanning, and structural analysis to map SLiMs recognised by human cyclins and uncover the rules that determine their specificity and affinity.
Örd et al. (Fri,) studied this question.