Perturbation of the Dimer Interface of Triosephosphate Isomerase and its Effect on Trypanosoma cruzi

Abstract

BackgroundChagas disease affects around 18 million people in the American continent. Unfortunately, there is no satisfactory treatment for the disease. The drugs currently used are not specific and exert serious toxic effects. Thus, there is an urgent need for drugs that are effective. Looking for molecules to eliminate the parasite, we have targeted a central enzyme of the glycolytic pathway: triosephosphate isomerase (TIM). The homodimeric enzyme is catalytically active only as a dimer. Because there are significant differences in the interface of the enzymes from the parasite and humans, we searched for small molecules that specifically disrupt contact between the two subunits of the enzyme from Trypanosoma cruzi but not those of TIM from Homo sapiens (HTIM), and tested if they kill the parasite.Methodology/Principal FindingsDithiodianiline (DTDA) at nanomolar concentrations completely inactivates recombinant TIM of T. cruzi (TcTIM). It also inactivated HTIM, but at concentrations around 400 times higher. DTDA was also tested on four TcTIM mutants with each of its four cysteines replaced with either valine or alanine. The sensitivity of the mutants to DTDA was markedly similar to that of the wild type. The crystal structure of the TcTIM soaked in DTDA at 2.15 Å resolution, and the data on the mutants showed that inactivation resulted from alterations of the dimer interface. DTDA also prevented the growth of Escherichia coli cells transformed with TcTIM, had no effect on normal E. coli, and also killed T. cruzi epimastigotes in culture.Conclusions/SignificanceBy targeting on the dimer interface of oligomeric enzymes from parasites, it is possible to discover small molecules that selectively thwart the life of the parasite. Also, the conformational changes that DTDA induces in the dimer interface of the trypanosomal enzyme are unique and identify a region of the interface that could be targeted for drug discovery.

Giardial Triosephosphate Isomerase as Possible Target of the Cytotoxic Effect of Omeprazole in Giardia lamblia

“…It is relevant to point out that others have demonstrated that triosephosphate isomerase has a cytotoxic effect on other parasites (47)(48)(49). Having a well-characterized molecular target (i.e., GlTIM) will help to develop more efficient and specific antigiardial drugs that can be used as a coadjuvant treatment or in cases of extremely virulent and resistant strains.…”

New chemotypes as Trypanosoma cruzi triosephosphate isomerase inhibitors: a deeper insight into the mechanism of inhibition

“…In fact, the identity of the 32 interfacial residues of TcTIM, TbTIM and LmTIM with the homologous HsTIM is approximately 52%. TIMs from T. cruzi, T. brucei and L. mexicana have 73.9% sequence identity and 92.4% similarity 9 . The potential use of protein-protein interfaces of homodimeric enzymes, as targets for drug discovery, has been reviewed 10 .…”

Leishmania braziliensis replication protein A subunit 1: molecular modelling, protein expression and analysis of its affinity for both DNA and RNA

“…differences at this region might be exploited for the discovery of molecules with pharmacological potential that perturb the complex formation of the RPA protein, following a similar approach to that used for the triosephosphate isomerase of T. cruzi [37].…”