Entamoeba histolytica:Computer-Assisted Modeling of Phosphofructokinase for the Prediction of Broad-Spectrum Antiparasitic Agents

Abstract

Pyrophosphate-dependent phosphofructokinase (PPi-PFK) is the rate-limiting glycolytic enzyme found in the pathogenic protistsEntamoeba histolytica, Giardia lamblia, Toxoplasma gondii, Trichomonas vaginalis,andNaegleria fowleri.The enzyme differs significantly from ATP-dependent phosphofructokinases found in humans and as such represents an important drug target. Current therapy for infections caused by these pathogens is inadequate, especially for children, pregnant women, and the immune compromised. The development of more selective, safer agents is imperative, as parasitic infections are currently a significant health threat worldwide and will likely become increasingly common agents of disease in the future. For the purpose of designing drugs to treat parasitic infections, we have constructed a model of PPi-PFK fromE. histolyticabased on the three-dimensional structure of the ATP-dependent PFK fromBacillus stearothermophilus.The model was used with the computer program Dock 3.5 (University of California, San Francisco) to predict the binding of pyrophosphate and selected bisphosphonates to the enzyme. The predicted drug–enzyme interactions suggested that two of these compounds would be competitive inhibitors of pyrophosphate. These drugs were tested againstE. histolyticaand inhibited the growth of amebaein vitro.This class of compounds may have broad-spectrum antiparasitic activity and, in the future, may facilitate the treatment of serious parasitic infections.