Identification of novel inhibitors and activity-based probes for signal peptidase I

Bacterial infections continue to be a threat to the well-being of mankind. As a result, there is a pressing need to find new protein targets for next-generation antibiotics. Bacterial signal peptidase I is an essential serine protease with an unusual catalytic machinery. It is involved in the secretory pathway and is considered a potential future drug target. In this project, we will set up an assay for this protease and screen an in-house collection of small molecules that have reactivity against serine residues. The assay itself will be based on a synthetic peptide that becomes fluorescent after cleavage. This assay will be compatible with future high throughput screening. The small molecules have shown reactivity against some unusual serine proteases before. It is therefore likely that some show activity towards signal peptidase I as well. The active small molecules will be derivatized in order to be used as “activity-based probes”. These are molecules that modify the active target protease and allow detection by a variety of methods, including mass spectrometry and microscopy. Overall, successful execution of this project will form an important step forward towards novel compounds targeting bacteria. Moreover, it will enable a variety of future research in the development of antibiotics and methods to visualize infection.