Rationally-driven targeting of dihydroorotate dehydrogenase: key enzyme of pyrimidine biosynthesis pathway

Pyrimidine Biosynthesis Pathway (PBP) plays a pivotal role in nucleic acids metabolism and in cellular homeostasis; accordingly, it emerges as a promising source of therapeutically relevant targets. Among PBP enzymes, dihydroorotate dehydrogenase (DHODH) has been explored for the treatment of various conditions, including autoimmune disorders, acute myeloid leukemia and more recently, in host-pathogen directed therapies for infectious diseases. With this regard, human DHODH (hDHODH) has been deeply investigated as an essential player for maintaining the fitness of the host, whose survival must be assured and eventually balanced with that of the pathogen. While the literature extensively covers hDHODH characterization, Mycobacterium tuberculosis DHODH (MtDHODH) lacks biochemical and structural assessments. Tuberculosis (TB) is an ancient infectious disease that still remains one of the main causes of mortality worldwide. Despite several efforts, an effective treatment to eradicate TB is currently unavailable, highlighting the urgency of innovative therapies. In this scenario, our research aims to enrich the understanding of hDHODH while concurrently addressing the scientific gap surrounding MtDHODH, proposing it as a new antitubercular drug target. Through collaboration with the Medicinal Chemistry and Phytochemistry units (from UNITO and UNIUPO), we conducted an extensive exploration of DHODH, investigating the molecular details of druggable sites supported by rigorous biochemical analysis. Through biochemical and structural investigations, we validated potent hDHODH inhibitors contributing to the existing knowledges supporting a rational drug discovery pipeline. Additionally, the collaboration with the Mycobacterial unit at the Pasteur Institute moved us forward in the microbiological evaluation of candidate molecules, to define a new paradigm for rationally driven MtDHODH drug design, contributing to the development of effective antitubercular therapies.