The Role of Carbamoyl Phosphate Synthetase (EC 6.3.5.5) in L-Glutamine and L-Glutamate Pathway Metabolism in Trypanosoma cruzi

• Grant number: 24/22343-1
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: October 01, 2025
• End date: September 30, 2029
• Field of knowledge: Biological Sciences - Parasitology - Protozoology of Parasites
• Principal Investigator: Ariel Mariano Silber
• Grantee: Luyi Zhao
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/12938-0 - Amino acid metabolism in Trypanosoma cruzi: a toolbox to survive in hostile environments, AP.TEM

Abstract

Chagas disease, also known as American trypanosomiasis, is a public health problem. There are approximately 30,000 new cases worldwide, which are caused by Trypanosoma cruzi. Chagas disease has now become a global health issue, because of migrations. Current recommended treatment uses drugs such as benznidazole and nifurtimox, which have limited efficacy and safety. Therefore, there is an urgent need for new therapeutic approaches. The parasite life cycle involves insect vectors and mammalian hosts. T. cruzi exhibits uncommon metabolic characteristics, such as aerobic fermentation of glucose, and reliance on amino acids like proline and histidine (among others) for ATP production and proliferation. In particular, amino acids metabolism is relevant for T. cruzi survival in the stress conditions the parasite encounters in its different hosts. Two of the amino acids which metabolism has been partially addressed are L-glutamate and L-glutamine. The interconversion between glutamate and glutamine is recognized as a key step for -NH2 distribution across different metabolic pathways, NH4+ administration, and for ATP production in T. cruzi. The biosynthesis of glutamine from glutamate by the glutamine synthetase of T. cruzi has already been studied by our group. However, the role of the carbamoyl phosphate synthetase II (CPS II, EC 6.3.5.5) (one of the enzymes that convert glutamine into glutamate) remains completely uncharacterized. Even more, how these reactions are balanced and collectively impact the parasite biology remains unclear. Does CPS II affect the Glu-Gln pathway, particularly in terms of its impact on energy metabolism? Does the interplay between these enzymes influence energy-demanding processes such as proliferation, differentiation, mammalian host-cell infection, or resistance to stress conditions? We hypothesize that CPS II may be associated to the production of ATP and thus affect the proliferation, differentiation, host-cell invasion, and survival in challenging environments that the parasite faces during its complex life cycle. In this project, we propose to improve our understanding of the role of CPS II in the metabolism of glutamate and glutamine, and in a more general way, its role in the life cycle of T. cruzi. By knocking out the CPS II gene, we plan to identify the role of this enzyme in T. cruzi energy metabolism and to explore the potential mechanisms for its possible association with parasite differentiation. Addressing these objectives could expand our understanding of CPS II function in T. cruzi, and contribute to uncovering new targets for future therapeutic strategies for Chagas disease. (AU)