Analytical tools to measure protein-protein interactions and development of inhibitors active in vivo


Joachim Jose, PharmaCampus, Insitute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität, 48149 Münster, Germany (joachim.jose@uni-muenster.de)

Protein-Protein-Interactions (PPI) are involved in basically all biological processes within the human body. Recent studies estimate the human interactome to consist of around 130.000 – 650.000 different PPI. Addressing selected protein-protein interactions (PPIs) by small molecules that bind and interfere appears to be a promising and emerging target for drug discovery. In contrast to the active site of an enzyme or the ligand binding site of a receptor, however, the PPI interface in general does not represent a cavity, but rather a surface exposed domain or area of the protein. Hydrophobic patches are important in such interfaces, but the number and role of hydrogen bonds and water molecules can be rather different from classical cavities. Furthermore, the influence of protein flexibility and induced fitting is more difficult to predict, than it is enzymes or a receptors.

Applying bacterial surface display, click chemistry and flow cytometry we developed screening assays to identify small molecule PPI inhibitors for human cancer target proteins. The assays developed could be used to identify inhibitors of heterologous PPIs, as in the case of human protein kinase CK2 [1] and transcription factor Myb [2,3], as well as inhibitors of homologous PPI as in the case of human HSP90 [4,5]. KD values of the new compounds identified with the corresponding PPI targets were determined by microscale thermophoresis (MST). This strategy led to new potent small molecule PPI inhibitors in the nanomolar range that turned out to be active in a mouse model as well as in primary human leukemia cells.

In conclusion, the strategy as applied here, by combining bacterial surface display, click chemistry  and flow cytometry for the rapid screening for PPIs and IC50 determination, followed by MST for KD measurement of the best candidates appears to be a practical and valuable way to identify novel small molecule inhibitors of PPIs.

Acknowledgments: I am grateful for the valuable contributions of my colleagues Karsten Niefind, Karl-Heinz Klempnauer, Holger Gohlke, Julia Hauer and their groups, as well as to my co-workers involved in this work.

References:

[1] ACS Chem. Biol. 8 (2012) 901-907; [2] Mol. Cancer. Ther. 14 (2015)1276-1285; [3] Blood 127 (2016)1173-1182; [4] BBA Gen. Subj. 1860 (2016) 1043-1055; [5] Blood, 132 (2019 307-320.


Abstract Reference & Short Personal Biography of Presenting Author

Joachim Jose studied biology at the University Saarbrücken, and graduated in 1994 with a thesis on the reaction mechanism of bacterial ureases. During his Post-Doc at the MPI for Biology in Tübingen and the MPI for Infection Biology, Berlin (1994-97), he was mainly involved in the discovery of a new family of secreted proteins: the Autotransporters. From 1998 until 2004, he was an Assistant Professor (C1) at Saarland University, Saarbrücken and obtained his habilitation with a thesis on the evolutive drug and biocatalyst design by bacterial surface display. 2004 he accepted a call for an Associate Professor in Bioanalytics at the Institute of Pharm. Med. Chemistry at Heinrich-Heine-University Düsseldorf, where he was appointed Head of the Institute in 2008. Since 2011 he is Full Professor and Chair in Pharm. Med. Chemistry at the PharmaCampus of the Westfälische Wilhelms-University Münster, and is executive Director of the Institute.

His publication record includes > 177 papers, 18 patent and patent applications, 94 invited lectures and 298 conference contributions. In addition he was mentor of 34 completed PhD theses.

His awards include the GDCh/DPhG Innovation Award in Medicinal Chemistry (1998) and the SaarLB Science Award (2004). In 2009 he was elected corresponding member of the French National Academy of Pharmacy and in 2013 he obtained the Medal of the Faculty for Biology and Pharmacy of the University Claude Bernard, Lyon, France.

Joachim Jose is co-founder of two start-up companies in the field of 'drug screening and selection' (Pharmacelsus, founded in 2000) and 'biocatalytic synthesis and evolutive drug design' (Autodisplay Biotech, 2008).

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