Identification of chemical compounds to inhibit the caseinolytic protease ClpXP complex and evaluate their biological activity

• Applicant: Professor Dr. Stephan A. Sieber
• Subject Area: Pharmacy
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 282324388

In the search for new drugs against multiresistant pathogens we utilize a strategy which contrary to classical antibiotics does not kill bacteria but disarms their pathogenicity (virulence). The advantage of the anti-virulence approach is a lack of selective pressure leading to reduced resistance development and longer lasting drugs.Important regulators of bacterial virulence are the caseinolytic protease ClpP and is associated chaperone ClpX. While we were able to specifically inhibit ClpP and correspondingly virulence in S. aureus with beta-Lactones, their limited stability represents a major challenge for pharmacological application. This research proposal aims to identify novel ClpP and ClpX based virulence inhibitors with suitable pharmacological properties for in vivo application. In initial experiments we already identified reversible ClpP inhibitors via a high-throughput-screen (HTS). Their binding mode into ClpP will be investigated in detail by mutational studies. The outcome of these experiments will be utilized for the synthesis of optimized derivatives which will be tested for improved enzyme inhibition and anti-virulence properties. As ClpX represents an additional important target for an anti-virulence approach we will perform an HTS at the FMP in Berlin to identify the first ClpP/ClpX specific inhibitors. All screening hits will be again optimized and the most promising compounds further modified with an alkyne handle as well as with an aziridine photolinker in order to analyze their target selectivity. Finally, these molecules will be tested for their pharmacological properties and in case of suitable parameters tested for efficacy in a mouse abscess model.

• DFG Programme: Research Grants