| Accession: | |
|---|---|
| Functional site class: | Yeast Cdc14 phosphatase docking site |
| Functional site description: | Progression through the cell cycle is characterized by a quantitative increase in Cdk phosphorylation activity, coupled with changes in the substrate specificities of the sequentially expressed cyclin activators. This Cdk activity is modulated by opposing phosphatase activities. The conserved dual-specificity phosphatase Cdc14 is required for mitotic exit in budding yeasts. Cdc14 is released from association with its stoichiometric inhibitor Net1 during mitotic exit, allowing nuclear translocation and the sequential dephosphorylation of its targets. The non-catalytic, N-terminal domain of Cdc14 harbours a hydrophobic binding pocket that recognizes the PxL docking motif on substrates. This docking event enhances target recognition and dephosphorylation, even in the case of suboptimal phosphosites. The docking site often occurs within clusters of Cdk phosphorylation sites but also at a considerable distance from the phosphorylation site itself. |
| ELM Description: | The Cdc14 substrate docking PxL motif interacts with a hydrophobic groove of Cdc14. The motif ΦxxφPxLxΦ was derived from a phage display-based peptide screen of the budding yeast proteome, together with a mutational scanning peptide array of the Cbk1 protein kinase substrate and structural studies of two substrates. Cdc14-interacting peptides derived from the phage display assay harbour a PxL motif, and known interactors of Cdc14 were among the highly enriched hits, three confirmed to bind Cdc14 in vitro (Kataria,2018). Structural and evolutionary analysis of the high-ranking phage display hits led to the formulation of the [FYLIM]xx[YVILA]PxL motif pattern, where the core PxL motif (P at +1) is accompanied by a large hydrophobic/aromatic residue in the -4 position and a second hydrophobic residue in the -1 position. The contribution of the residue in the +5 position was ambiguous based on peptide array analysis (Kataria,2018) and a variety of dissimilar residues (P, Y, H, Q, T, A) have been observed in this position among the experimental instances and their close homologues. Structural analysis of Cdc14 interaction with two peptides derived from Cbk1 (6G84) and Sic1 (6G86) shows that they adopt similar conformations and mediate a comparable array of interactions with Cdc14. The central proline and leucine side chains of the PxL motif point into the core of the hydrophobic pocket. Three h-bonds between the peptide main chain and the Q106 and W108 side chains of Cdc14 further stabilize and position these core side chains. N-terminal to the PxL, the aliphatic residues at the −1 position (V85 in Cbk1 and A55 in Sic1) engage in hydrophobic interactions with the Cdc14 pocket, while the −4 phenylalanines stack against Cdc14 Y60. At the +5 position, Y90 in Cbk1 and P60 in Sic1 engage with Cdc14 W108. The orientation of the docking and active sites in the Cdc14 dimer indicate that dimerization might enhance the trans-dephosphorylation of substrates. The motif is so far identified only in budding yeast. |
| Pattern: | [FYLIM]..[YVILA]P.L.. |
| Pattern Probability: | 0.0002446 |
| Present in taxon: | Fungi |
| Interaction Domain: |
DSPn (PF14671)
Dual specificity protein phosphatase, N-terminal half
(Stochiometry: 1 : 1)
|