title: Development of a high-throughput screening-compatible assay to identify inhibitors of the CK2α/CK2β interaction.
abstract: Increased activity of protein kinase CK2 is associated with various types of cancer, neurodegenerative diseases, and chronic inflammation. In the search for CK2 inhibitors, attention has expanded toward compounds disturbing the interaction between CK2α and CK2β in addition to established active site-directed approaches. The current article describes the development of a fluorescence anisotropy-based assay that mimics the principle of CK2 subunit interaction by using CK2α(1-335) and the fluorescent probe CF-Ahx-Pc as a CK2β analog. In addition, we identified new inhibitors able to displace the fluorescent probe from the subunit interface on CK2α(1-335). Both CF-Ahx-Pc and the inhibitors I-Pc and Cl-Pc were derived from the cyclic peptide Pc, a mimetic of the C-terminal CK2α-binding motif of CK2β. The design of the two inhibitors was based on docking studies using the known crystal structure of the Pc/CK2α(1-335) complex. The dissociation constants obtained in the fluorescence anisotropy assay for binding of all compounds to human CK2α(1-335) were validated by isothermal titration calorimetry. I-Pc was identified as the tightest binding ligand with a KD value of 240nM and was shown to inhibit the CK2 holoenzyme-dependent phosphorylation of PDX-1, a substrate requiring the presence of CK2β, with an IC50 value of 92μM.
authors.affiliation: Institute of Biochemistry, Department of Chemistry, University of Cologne, D-50674 Cologne, Germany; KinaseDetect ApS, DK-5220 Odense, Denmark.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hochscherf
authors.affiliation: Institute of Biochemistry, Department of Chemistry, University of Cologne, D-50674 Cologne, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Lindenblatt
authors.affiliation: Institute of Pharmacology, University Hospital of Cologne, D-50931 Cologne, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Steinkrüger
authors.affiliation: Institute of Biochemistry, Department of Chemistry, University of Cologne, D-50674 Cologne, Germany.
authors.forename: Eungyoung
authors.initials: E
authors.lastname: Yoo
authors.affiliation: Center for Bioinformatics, Saarland University, D-66041 Saarbrücken, Germany.
authors.forename: Özlem
authors.initials: Ö
authors.lastname: Ulucan
authors.affiliation: Institute of Pharmacology, University Hospital of Cologne, D-50931 Cologne, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Herzig
authors.affiliation: KinaseDetect ApS, DK-5220 Odense, Denmark; Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark.
authors.forename: Olaf-Georg
authors.initials: OG
authors.lastname: Issinger
authors.affiliation: Center for Bioinformatics, Saarland University, D-66041 Saarbrücken, Germany.
authors.forename: Volkhard
authors.initials: V
authors.lastname: Helms
authors.affiliation: Medical Biochemistry, Saarland University, D-66421 Homburg, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Götz
authors.affiliation: Institute of Biochemistry, Department of Chemistry, University of Cologne, D-50674 Cologne, Germany. Electronic address: ines.neundorf@uni-koeln.de.
authors.forename: Ines
authors.initials: I
authors.lastname: Neundorf
authors.affiliation: Institute of Biochemistry, Department of Chemistry, University of Cologne, D-50674 Cologne, Germany. Electronic address: karsten.niefind@uni-koeln.de.
authors.forename: Karsten
authors.initials: K
authors.lastname: Niefind
authors.affiliation: Institute of Pharmacology, University Hospital of Cologne, D-50931 Cologne, Germany. Electronic address: markus.pietsch@uk-koeln.de.
authors.forename: Markus
authors.initials: M
authors.lastname: Pietsch
mesh_terms: D001667:Binding, Competitive; D002147:Calmodulin / Q000378:metabolism; D047390:Casein Kinase II / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D005454:Fluorescence Polarization / Q000379:methods; D005456:Fluorescent Dyes; D057166:High-Throughput Screening Assays / Q000379:methods*; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D062105:Molecular Docking Simulation; D010456:Peptides, Cyclic / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D021122:Protein Subunits; D015534:Trans-Activators / Q000378:metabolism
chemical_list: D002147:Calmodulin; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D018398:Homeodomain Proteins; D010456:Peptides, Cyclic; D021122:Protein Subunits; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; C570325:CSNK2A1 protein, human; D047390:Casein Kinase II
keywords: Fluorescence anisotropy; Isothermal titration calorimetry; Molecular docking; Protein kinase CK2; Protein–protein interactions