title: Identification of a Potent Allosteric Inhibitor of Human Protein Kinase CK2 by Bacterial Surface Display Library Screening.
abstract: Human protein kinase CK2 has emerged as promising target for the treatment of neoplastic diseases. The vast majority of kinase inhibitors known today target the ATP binding site, which is highly conserved among kinases and hence leads to limited selectivity. In order to identify non-ATP competitive inhibitors, a 12-mer peptide library of 6 × 10⁵ variants was displayed on the surface ofE. coliby autodisplay. Screening of this peptide library on variants with affinity to CK2 was performed by fluorophore-conjugated CK2 and subsequent flow cytometry. Single cell sorting of CK2-boundE. coliyielded new peptide variants, which were tested on inhibition of CK2 by a CE-based assay. Peptide B2 (DCRGLIVMIKLH) was the most potent inhibitor of both, CK2 holoenzyme and the catalytic CK2α subunit (IC50= 0.8 µM). Using different ATP concentrations and different substrate concentrations for IC50determination, B2 was shown to be neither ATP- nor substrate competitive. By microscale thermophoresis (MST) the KDvalue of B2 with CK2α was determined to be 2.16 µM, whereas no binding of B2 to CK2β-subunit was detectable. To our surprise, besides inhibition of enzymatic activity, B2 also disturbed the interaction of CK2α with CK2β at higher concentrations (≥25 µM).
authors.affiliation: Institut für Pharmazeutische und Medizinische Chemie, PharmaCampus, Westfälische Wilhelms-Universität Münster, Correnstraße 48, D-48149 Münster, Germany. christian.nienberg@uni-muenster.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Nienberg
authors.affiliation: Institut für Pharmazeutische und Medizinische Chemie, PharmaCampus, Westfälische Wilhelms-Universität Münster, Correnstraße 48, D-48149 Münster, Germany. claudia.reicheneder@gmx.de.
authors.forename: Claudia
authors.initials: C
authors.lastname: Garmann
authors.affiliation: Institut für Pharmazeutische und Medizinische Chemie, PharmaCampus, Westfälische Wilhelms-Universität Münster, Correnstraße 48, D-48149 Münster, Germany. gratz.andreas@gmail.com.
authors.forename: Andreas
authors.initials: A
authors.lastname: Gratz
authors.affiliation: Institut für Pharmazeutische und Medizinische Chemie, PharmaCampus, Westfälische Wilhelms-Universität Münster, Correnstraße 48, D-48149 Münster, Germany. andre.bollacke@uni-muenster.de.
authors.forename: Andre
authors.initials: A
authors.lastname: Bollacke
authors.affiliation: Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, Kirrberger Str., Geb. 44, D-66421 Homburg, Germany. claudia.goetz@uks.eu.
authors.forename: Claudia
authors.initials: C
authors.lastname: Götz
authors.affiliation: Institut für Pharmazeutische und Medizinische Chemie, PharmaCampus, Westfälische Wilhelms-Universität Münster, Correnstraße 48, D-48149 Münster, Germany. joachim.jose@uni-muenster.de.
authors.forename: Joachim
authors.initials: J
authors.lastname: Jose
keywords: autodisplay; human protein kinase CK2; non ATP-competitive inhibitor; peptide