Spatial exclusivity combined with positive and negative selection of phosphorylation motifs is the basis for context-dependent mitotic signaling.
The timing and localization of events during mitosis are controlled by the regulated phosphorylation of proteins by the mitotic kinases, which include Aurora A, Aurora B, Nek2 (never in mitosis kinase 2), Plk1 (Polo-like kinase 1), and the cyclin-dependent kinase complex Cdk1/cyclin B. Although mitotic kinases can have overlapping subcellular localizations, each kinase appears to phosphorylate its substrates on distinct sites. To gain insight into the relative importance of local sequence context in kinase selectivity, identify previously unknown substrates of these five mitotic kinases, and explore potential mechanisms for substrate discrimination, we determined the optimal substrate motifs of these major mitotic kinases by positional scanning oriented peptide library screening (PS-OPLS). We verified individual motifs with in vitro peptide kinetic studies and used structural modeling to rationalize the kinase-specific selection of key motif-determining residues at the molecular level. Cross comparisons among the phosphorylation site selectivity motifs of these kinases revealed an evolutionarily conserved mutual exclusion mechanism in which the positively and negatively selected portions of the phosphorylation motifs of mitotic kinases, together with their subcellular localizations, result in proper substrate targeting in a coordinated manner during mitosis.
PubMed ID: 21712545
PMC ID: PMC3939359
Article link: Sci Signal.
Grant support: CA-112967 NCI NIH HHS , ES-015339 NIEHS NIH HHS , GM-60594 NIGMS NIH HHS , GM-68762 NIGMS NIH HHS , 06-0029 Worldwide Cancer Research, 069035 Wellcome Trust , 078020 Wellcome Trust , 082828 Wellcome Trust , A7820 Cancer Research UK, A9363 Cancer Research UK, MC_U117584228 Medical Research Council , P50 GM068762 NIGMS NIH HHS , R01 ES015339 NIEHS NIH HHS , R01 GM060594 NIGMS NIH HHS , U54 CA112967 NCI NIH HHS
Genes referenced: aurka aurkb ccnb1.2 cdk1 nek2 plk1