Anti-microbial compounds targeting the alternative thymidylate synthase ThyX – AMTHYX

The growing problem of antibiotics resistance points to an urgent need for new anti-infective therapies. However, the rate of new antimicrobial compounds to be developed by the pharmaceutical industry alone will not be sufficient to meet the expected need for the foreseeable future. Therefore, active collaborations of academic laboratories with the pharmaceutical industry are needed in order to provide cost-effective means for developing new molecule entities towards biomedical applications.

The present project focuses on ThyX proteins (discovered by the partner 1) as anti-microbial targets. These essential enzymes form a novel family of thymidylate synthases that produce dTMP (thymidylate) in the absence of the canonical thymidylate synthase ThyA found in humans. Essential ThyX proteins are required for de novo DNA synthesis in a large number of bacterial human pathogens like e. g. Mycobacterium tuberculosis, Helicobacter pylori, Campylobacter jejuni and Chlamydia and Borrelia species, and do not share sequence or structural similarity with human ThyA. Importantly, ThyX proteins have never been targeted by anti-microbials.

The project, comprising 4 partners including a valorization structure (INSERM Transfert), is designed to obtain the proof of concept for the anti-microbial activity of 1,4- naphthoquinones that act as efficient and specific inhibitors of ThyX proteins. The lead compounds were identified by Partner 1 using ThyX proteins in activity-based screenings, and were found to inhibit the growth of a large number of pathogenic bacteria expressing ThyX proteins, notably Helicobacter and Mycobacterium species, without affecting the growth of Escherichia coli or human cell lines that use the classical thymidylate synthase ThyA.

We aim to further optimize the in vitro inhibitory and pharmacokinetic properties of the existing lead compounds by custom synthesis of new lead derivatives (subcontract Roowan, see Partner 1) and to further validate their efficiency in vivo using an animal model for infections by Helicobacter pylori, already established at the Pasteur Institut (Partner 2). We anticipate that the in vivo anti-microbial activity of our compounds can be optimized by structure-based design of new compounds with tighter binding to the active site of ThyX proteins (Partners 3 and 1), and by modulating a range of physico-chemical properties resulting in improved bioavailability. In parallel, the Epicentre research center [Mbarara University of Sciences and Technology (Uganda)] will evaluate the activity of these inhibitors on the growth of Mycobacterium tuberculosis isolated from patients.

Consistent with the project, a patent application concerning the use of ThyX inhibitors for the prevention and/or treatment of bacterial infections was filed by INSERM Transfert in April 2010.

This project has strong potential to provide new anti-microbial compounds, needed to address the increasing problem of anti-biotic resistance routinely observed in clinical settings. Our primary goal is to license our optimized molecules to the pharmaceutical industry after obtaining the proof-of-concept using animal models, thus rendering the inhibitor eligible for preclinical development.