Backbone NMR assignments of the essential oxidoreductase tryparedoxin from the human pathogenic parasite Trypanosoma cruzi.

Abstract

Over 7 million people worldwide are affected with Chagas disease, a lifelong debilitating and potentially fatal Neglected Tropical Disease caused by the single cell protozoan parasite Trypanosoma cruzi. To maintain viability and to reproduce under the harsh conditions within a host organism, pathogens express a variety of protecting enzymes and virulence factors that can serve as potential drug targets. To protect itself from redox stress, T. cruzi takes advantage of a unique thiol metabolism. For instance, a cytosolic peroxide clearance cascade is centered on the conserved oxidoreductase Tryparedoxin (Tpx). Tpx efficiently distributes reducing equivalents across the parasitic cell through the promiscuous yet selective binding of numerous up- and downstream clients. However, the exact structure and binding interfaces of this central protein binding hub remain unknown. To study the redox-dependent structural dynamics of T. cruzi Tpx, and its interactions with binding partners, we determined the ¹H, ¹³C, ¹⁵N-backbone NMR assignments of the enzyme in the reduced and oxidized state. In agreement with earlier NMR studies on Tpx from related protozoans, we report redox-dependent changes in the enzyme's dithiol active site that could play a crucial role in the recognition of physiological substrates and should be considered in the rational design of small molecule inhibitors.