A new linear cyclin docking motif that mediates exclusively S‐phase CDK‐specific signaling

Abstract

Cyclin‐dependent kinases (CDKs), the master regulators of cell division, are activated by different cyclins at different cell cycle stages. In addition to being activators of CDKs, cyclins recognize various linear motifs to target CDK activity to specific proteins. We uncovered a cyclin docking motif, NLxxxL, that contributes to phosphorylation‐dependent degradation of the CDK inhibitor Far1 at the G1/S stage in the yeast Saccharomyces cerevisiae. This motif is recognized exclusively by S‐phase CDK (S‐CDK) Clb5/6‐Cdc28 and is considerably more potent than the conventional RxL docking motif. The NLxxxL and RxL motifs were found to overlap in some target proteins, suggesting that cyclin docking motifs can evolve to switch from one to another for fine‐tuning of cell cycle events. Using time‐lapse fluorescence microscopy, we show how different docking connections temporally control phosphorylation‐driven target degradation. This also revealed a differential function of the phosphoadaptor protein Cks1, as Cks1 docking potentiated degron phosphorylation of RxL‐containing but not of NLxxxL‐containing substrates. The NLxxxL motif was found to govern S‐cyclin‐specificity in multiple yeast CDK targets including Fin1, Lif1, and Slx4, suggesting its wider importance.

Proteome-wide screening for mitogen-activated protein kinase docking motifs and interactors

“…In other systems, docking is not absolutely required for phosphorylation in vivo , yet tuning the strength of such interactions can reportedly set phosphorylation rate. For example, SLiM-mediated recruitment to cyclin-dependent kinases through the cyclin subunit substrates controls the timing of phosphorylation within the cell division cycle ( 42, 43 ). In the case of the yeast LATS/NDR kinase Cbk1, an optimal docking sequence is not absolutely required for substrate phosphorylation yet confers robustness to perturbations that attenuate kinase activity ( 44 ).…”

Cdc4 phospho-degrons allow differential regulation of Ame1CENP-U protein stability across the cell cycle

“…This makes it likely that additional, yet undiscovered degron signals exist. These could involve both non-consensus sites phosphorylated by Cdk1 and also kinases in addition to Cdk1, as is the case for multiple other SCF substrates ( Faustova et al, 2021 ; Kõivomägi et al, 2011 ; Örd et al, 2019a ). An additional key substrate may be Okp1, and some Cdk1-dependent phosphorylation sites (e.g., Ser70) have been reported ( Holt et al, 2009 ), which are not direct Cdk1 sites.…”

Differentially accessible Cdc4 phospho-degrons regulate Ctf19CCANkinetochore subunit stability in mitosis

“…Here, degron sequences located on multiple subunits and phosphorylated in different combinations might be required for effective binding by Cdc4. This could involve both non-consensus sites phosphorylated by Cdk1, and also kinases in addition to Cdk1, as is the case for multiple other SCF substrates (Faustova et al, 2021; Koivomagi et al, 2011; Ord et al, 2019a). An additional key substrate may be Okp1, and some Cdk1-dependent phosphorylation sites (e.g.…”