The relevance of sulphur amino acids and their metabolism in the biology of Trypanosoma cruzi

• Grant number: 22/14959-7
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: November 01, 2023
• End date: October 31, 2026
• Field of knowledge: Biological Sciences - Parasitology - Protozoology of Parasites
• Principal Investigator: Ariel Mariano Silber
• Grantee: María Sol Ballari
• 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 (Trypanosoma cruzi) is a parasitic disease classified within the group of Neglected Tropical Diseases, and constitutes a public health problem in most Latin American countries, mainly affecting socio-economically vulnerable sectors of the population. T. cruzi metabolizes amino acids, and uses them as important energy sources, in addition to their use in several biological processes such as differentiation, resistance to stress conditions, and host-cell invasion. Cysteine (Cys) is a sulphur amino acid with a fundamental role in the structure, stability and catalytic function of many proteins. Cys may be related to energy metabolism in the parasite by its conversion to pyruvate, and is the predominant source of -SH groups in the biosynthesis of sulphur-containing molecules. On the other hand, sulphur-containing amino acids play an important role in methylation of macromolecules and synthesis of polyamines. Cys can be biosynthesized through two pathways: 1) transsulphuration pathway, involving formation of cystathionine from serine (Ser) and homocysteine (HCys), the latter obtained from methionine (Met) in three steps; 2) two-step de novo synthesis from Ser, using SH2 as a sulphur source. There are not known Met synthesis pathways in T. cruzi, hence it has to be uptaken from the extracellular media, but the parasite counts with a "rescue" system to regenerate Met from HCys in one step. We consider it relevant to characterize in depth the metabolic connection between Met and HCys, and how it influences the Cys balance. The effect caused by Met, HCys and Cys in the bioenergetics and resistance to nutricional stress will be evaluated. It will be a priority of this project to understand the role of enzymes involved in the Met-HCys interconversion: S-adenosylmethionine synthetase (AdeMetS), S-adenosylhomocysteine hydrolase (AdeHCysH) and homocysteine S-methyltransferase (HMT). This will include their kinetic characterization, as well as the production of knockout (KO) lineages of T. cruzi for their genes by CRISPR/Cas9 technology. Metabolic profiles will be determined for KO and control strains, through NMR- and MS-metabolomics assays, in order to find changes in metabolome caused by enzyme depletion. The study of the Met-HCys metabolic cycle will allow us to better understand the role of sulphur amino acids in the complex amino acid metabolic network of T. cruzi, and in this way we can identify new potential therapeutic targets. (AU)