Deciphering the interaction of clustered phosphorylation sites in a multisite phosphorylation network – example of Ndd1 protein

Abstract

Multisite phosphorylation is a vital cellular regulatory process. Cdk1, the master cell cycle regulator, forms a complex with cyclin and Cks1, activating Cdk1 and directing it to specific target proteins. Phosphorylation by Cdk1 occurs at serine or threonine residues followed by proline, with enhanced specificity in the presence of arginine or lysine at the +3 position. Cks1 and the Clb2 phosphate-binding pocket facilitate secondary phosphorylation in phosphorylation clusters that tend to form in intrinsically disordered protein regions, generating signalling specificity. This thesis focuses on Ndd1, a transcriptional co-activator essential for nuclear division. The involvement of Cks1 and the recently discovered Clb2 phosphate-binding pocket is critical for Ndd1 multisite phosphorylation. By investigating a specific phosphorylation cluster within Ndd1, this thesis aims to unravel the complex phosphorylation networks mediated by clustering, Cks1, and the Clb2 phosphate-binding pocket.