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Hexose uptake in Trypanosoma cruzi: structure-activity relationship between substrate and transporter
1Laboratoire Biologie Moléculaire et Immunologie de Protozoaires Parasites, Université Bordeaux II, URA 1637, Centre National de la Recherche Scientifique, Bordeaux, France.
The Biochemical Journal
|July 15, 1996
Summary
The Trypanosoma cruzi hexose transporter (TcrHT1) functions similarly in mammalian cells, transporting glucose and fructose. Arginine residues are crucial for substrate binding, distinguishing it from mammalian glucose transporters.
Area of Science:
- Molecular biology
- Parasitology
- Biochemistry
Background:
- Trypanosoma cruzi causes Chagas disease, relying on hexose transporters for energy.
- Understanding T. cruzi hexose transporters is crucial for developing antiparasitic therapies.
Purpose of the Study:
- To functionally characterize the TcrHT1 hexose transporter from Trypanosoma cruzi.
- To elucidate substrate specificity and identify key amino acid residues in the TcrHT1 binding site.
Main Methods:
- Heterologous expression of TcrHT1 in Chinese hamster ovary (CHO) cells.
- Kinetic analysis using D-glucose analogues and D-fructose.
- Chemical modification of amino acid side chains to probe the substrate-binding site.
Main Results:
- TcrHT1 expressed in CHO cells exhibited kinetics similar to native T. cruzi epimastigote transporters.
- TcrHT1 showed distinct substrate recognition compared to T. brucei and mammalian GLUT transporters, notably transporting D-fructose.
- Arginine residues were identified as critical for substrate binding, with phenylglyoxal protecting against modification.
Conclusions:
- TcrHT1 is the primary hexose transporter in T. cruzi epimastigotes.
- TcrHT1 possesses unique substrate transport capabilities, including D-fructose, and a distinct binding site mechanism involving arginine residues.