title: Functional display of heterotetrameric human protein kinase CK2 on Escherichia coli: a novel tool for drug discovery.
abstract: BACKGROUND
  Human protein kinase CK2 represents a novel therapeutic target for neoplastic diseases. Inhibitors are in need to explore the druggability and the therapeutic options of this enzyme. A bottleneck in the search for new inhibitors is the availability of the target for testing. Therefore an assay was developed to provide easy access to CK2 for discovery of novel inhibitors.
  
  
  RESULTS
  Autodisplay was used to present human CK2 on the surface of Escherichia coli. Heterotetrameric CK2 consists of two subunits, α and β, which were displayed individually on the surface. Co-display of CK2α and CK2β on the cell surface led to the formation of functional holoenzyme, as demonstrated by NaCl dependency of enzymatic activity, which differs from that of the catalytic subunit CK2α without β. In addition interaction of CK2α and CK2β at the cell surface was confirmed by co-immunoprecipitation assays. Surface displayed CK2 holoenzyme enabled an easy IC50 value determination. The IC50 values for the known CK2 inhibitors TBB and Silmitasertib were determined to be 50 and 3.3 nM, respectively.
  
  
  CONCLUSIONS
  Surface-displayed CK2α and CK2β assembled on the cell surface of E. coli to an active tetrameric holoenzyme. The whole-cell CK2 autodisplay assay as developed is suitable for inhibition studies. Furthermore, it can be used to determine quantitative CK2 inhibition data such as IC50 values. In summary, this is the first report on the functional surface display of a heterotetrameric enzyme on E. coli.
authors.affiliation: Institut für Pharmazeutische und Medizinische Chemie, PharmaCampus, Westfälische Wilhelms-Universität Münster, Corrensstr. 48, 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, Corrensstr. 48, 48149, Münster, Germany. andre.bollacke@uni-muenster.de.
authors.forename: Andre
authors.initials: A
authors.lastname: Bollacke
authors.affiliation: Lehrstuhl für Biophysik, Ruhr-Universität Bochum, Universitätsstr. 150, 44801, Bochum, Germany. stephan@bph.ruhr-uni-bochum.de.
authors.forename: Sara
authors.initials: S
authors.lastname: Stephan
authors.affiliation: Institut für Pharmazeutische und Medizinische Chemie, PharmaCampus, Westfälische Wilhelms-Universität Münster, Corrensstr. 48, 48149, Münster, Germany. Christian.nienberg@uni-muenster.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Nienberg
authors.affiliation: Université de Lyon, Université Lyon 1, Faculté de Pharmacie-ISPB, EA 4446 Biomolécules Cancer et Chimiorésistances, SFR Santé Lyon-Est CNRS UMS3453-INSERM US7, 69373, Lyon Cedex 8, France. marc.le-borgne@univ-lyon1.fr.
authors.forename: Marc
authors.initials: M
authors.lastname: Le Borgne
authors.affiliation: Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, Kirrberger Str., Geb. 44, 66421, Homburg, Germany. bccgoe@uks.eu.
authors.forename: Claudia
authors.initials: C
authors.lastname: Götz
authors.affiliation: Institut für Pharmazeutische und Medizinische Chemie, PharmaCampus, Westfälische Wilhelms-Universität Münster, Corrensstr. 48, 48149, Münster, Germany. joachim.jose@uni-muenster.de.
authors.forename: Joachim
authors.initials: J
authors.lastname: Jose
mesh_terms: D000595:Amino Acid Sequence; D047390:Casein Kinase II / Q000378:metabolism; D055808:Drug Discovery; D004926:Escherichia coli / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data
chemical_list: C570325:CSNK2A1 protein, human; D047390:Casein Kinase II