Identification of new inhibitors of the arginine transporter TcAAP3 from Trypanosoma cruzi through an in silico strategy

MARTINEZ SAYE; MACIEL BELEN; GALCERAN F; CHANTAL REIGADA; RENGIFO MARCOS; DIGIROLAMO, FABIO A.; MARIANA MIRANDA; PEREIRA CA

Montevideo

Workshop; NTD Network Early Career Researcher Conference; 2022

Trypanosoma cruzi is the causative agent of Chagas disease, which affects almost 7 million people mainly in Latin America. The parasite metabolism is widely based on amino acid consumption,both as alternative carbon and energy sources and as energy reservoirs. The amino acid arginine can be converted to phosphoarginine through a reversible reaction catalyzed by arginine kinase (AK): arginine + ATP P-arginine + ADP. Overexpression of arginine transporter TcAAP3 augmentsintracellular arginine and induces AK downregulation to compensate the increase in ATP consumption suggesting that T. cruzi?s viability can be affected through fluctuations in arginine uptake. Additionally, essentiality of arginine permease TbAAT5 from T. brucei, orthologous to TcAAP3, has been proved through RNAi assays. In this work we identify potential TcAAP3 inhibitors that may also have trypanocidal effect on T. cruzi. L-arginine was used as template molecule in a similarity-based virtual screening applied to 320,000 query compounds, including worldwide approved drugs and natural products among others. After thorough inspection, 45 compounds were selected for molecular docking assays. Since the 3D structure of the arginine transporter TcAAP3 is not available, we generated and refined a homology-based model using the crystal structure of the neutral amino acid transporter SLC38A9 (PDB 7KGV) as template. Next, molecular docking assays were performed to predict the binding of the potential inhibitors with the TcAAP3 model. From these results, 5 compounds were selected for in vitro assays, and are currently under evaluation as TcAAP3 inhibitors and as trypanocidal drugs. The 5 compounds selected are iobenguane, sulfaguanidine, isotretinoin, assymetric dimethylarginine and aminohippuric acid. Using a similar approach we have identified inhibitors of the proline and the polyamines transporters TcAAAP069 and TcPAT12 with trypanocidal action. New therapies are needed to treat Chagas disease and computeraided strategies allow the rapid identification of drug candidates.