Inhibition of Eimeria tenella CDK-Related Kinase 2: From Target Identification to Lead Compounds

• Published in: ChemMedChem Vol. 5; no. 8; pp. 1259 - 1271
• Main Authors: Engels, Kristin, Beyer, Carsten, Suárez Fernández, Maria L., Bender, Frank, Gaßel, Michael, Unden, Gottfried, Marhöfer, Richard J., Mottram, Jeremy C., Selzer, Paul M.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 02.08.2010; WILEY‐VCH Verlag
• Subjects: Adenosine Triphosphate - metabolism; Amino Acid Sequence; Animals; Benzimidazoles - chemistry; Benzimidazoles - therapeutic use; Binding Sites; bioinformatics; Chickens; coccidiosis; Coccidiosis - drug therapy; Computer Simulation; Cyclin-Dependent Kinase 2 - antagonists & inhibitors; Cyclin-Dependent Kinase 2 - metabolism; drug discovery; Eimeria tenella - enzymology; Humans; Molecular Sequence Data; Protein Kinase Inhibitors - chemistry; Protein Kinase Inhibitors - therapeutic use; Protozoan Proteins - antagonists & inhibitors; Protozoan Proteins - metabolism; Sequence Alignment; transferases; virtual screening
• ISSN: 1860-7179; 1860-7187
• DOI: 10.1002/cmdc.201000157

Apicomplexan parasites encompass several human‐ and animal‐pathogenic protozoans such as Plasmodium falciparum, Toxoplasma gondii, and Eimeria tenella. E. tenella causes coccidiosis, a disease that afflicts chickens, leading to tremendous economic losses to the global poultry industry. The considerable increase in drug resistance makes it necessary to develop new therapeutic strategies against this parasite. Cyclin‐dependent kinases (CDKs) are key molecules in cell‐cycle regulation and are therefore prominent target proteins in parasitic diseases. Bioinformatics analysis revealed four potential CDK‐like proteins, of which one—E. tenella CDK‐related kinase 2 (EtCRK2)—has already been characterized by gene cloning and expression.1 By using the CDK‐specific inhibitor flavopiridol in EtCRK2 enzyme assays and schizont maturation assays (SMA), we could chemically validate CDK‐like proteins as potential drug targets. An X‐ray crystal structure of human CDK2 (HsCDK2) served as a template to build protein models of EtCRK2 by comparative homology modeling. Structural differences in the ATP binding site between EtCRK2 and HsCDK2, as well as chicken CDK3, were addressed for the optimization of selective ATP‐competitive inhibitors. Virtual screening and “wet‐bench” high‐throughput screening campaigns on large compound libraries resulted in an initial set of hit compounds. These compounds were further analyzed and characterized, leading to a set of four promising lead compounds for development as EtCRK2 inhibitors. Targeting coccidiosis: Cyclin‐dependant kinases (CDKs) of the protozoan parasite Eimeria tenella, which causes the severe poultry disease coccidiosis, were identified from genomic sequence data. The cell cycle and most well‐characterized kinase (EtCRK2) of E. tenella were chemically validated as drug targets in enzyme and cell culture assays. Promising lead compounds were identified in a combined in silico/in vitro screening approach.