Publication Date:
2011-10-14
Description:
Multisite phosphorylation of proteins has been proposed to transform a graded protein kinase signal into an ultrasensitive switch-like response. Although many multiphosphorylated targets have been identified, the dynamics and sequence of individual phosphorylation events within the multisite phosphorylation process have never been thoroughly studied. In Saccharomyces cerevisiae, the initiation of S phase is thought to be governed by complexes of Cdk1 and Cln cyclins that phosphorylate six or more sites on the Clb5-Cdk1 inhibitor Sic1, directing it to SCF-mediated destruction. The resulting Sic1-free Clb5-Cdk1 complex triggers S phase. Here, we demonstrate that Sic1 destruction depends on a more complex process in which both Cln2-Cdk1 and Clb5-Cdk1 act in processive multiphosphorylation cascades leading to the phosphorylation of a small number of specific phosphodegrons. The routes of these phosphorylation cascades are shaped by precisely oriented docking interactions mediated by cyclin-specific docking motifs in Sic1 and by Cks1, the phospho-adaptor subunit of Cdk1. Our results indicate that Clb5-Cdk1-dependent phosphorylation generates positive feedback that is required for switch-like Sic1 destruction. Our evidence for a docking network within clusters of phosphorylation sites uncovers a new level of complexity in Cdk1-dependent regulation of cell cycle transitions, and has general implications for the regulation of cellular processes by multisite phosphorylation.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3228899/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3228899/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Koivomagi, Mardo -- Valk, Ervin -- Venta, Rainis -- Iofik, Anna -- Lepiku, Martin -- Balog, Eva Rose M -- Rubin, Seth M -- Morgan, David O -- Loog, Mart -- 079014/Z/06/Z/Wellcome Trust/United Kingdom -- 1253/Howard Hughes Medical Institute/ -- R01 GM069901/GM/NIGMS NIH HHS/ -- R01 GM069901-08/GM/NIGMS NIH HHS/ -- England -- Nature. 2011 Oct 12;480(7375):128-31. doi: 10.1038/nature10560.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Technology, University of Tartu, Tartu 50411, Estonia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21993622" target="_blank"〉PubMed〈/a〉
Keywords:
Adaptor Proteins, Signal Transducing/metabolism
;
Binding Sites
;
CDC2 Protein Kinase/metabolism
;
Cell Cycle Proteins/metabolism
;
Cyclin B/metabolism
;
Cyclin-Dependent Kinase Inhibitor Proteins/*metabolism
;
Cyclins/metabolism
;
Phosphorylation
;
Proteolysis
;
S Phase/*physiology
;
Saccharomyces cerevisiae/*cytology/*metabolism
;
Saccharomyces cerevisiae Proteins/*metabolism
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
Permalink
