Transport of Nutrients and Ions across Membranes of Trypanosomatid Parasites

Abstract

This chapter discusses the membrane transport mechanisms in Leishmania and Trypanosoma. It focuses on the transport of four groups of substrates: amino acids, sugars, protons, and calcium and discusses the structure and function of the membrane transporters of these substances . Leishmania and Trypanosoma are protozoan parasites that live inside mammalian hosts, either intracellularly or extracellularly. The occurrence of a controlled transport of nutrients and ions into and from parasite cells is important for the maintenance of intracellular homeostasis. The level of expression and function of such membrane transporters is therefore critical for parasite survival inside their hosts. A regulation of intracellular pH and proton motive force is discussed in Leishmania and (2) T. brucei . Catabolism of D-glucose in Trypanosoma and Leishmania occurs in closed organelles called glycosomes. These organelles contain most of the glycolytic enzymes, including hexokinase, the enzyme responsible for the first step in glycolysis. The glycosomal membrane serves as a permeability barrier to most glycolytic intermediates. Substrate recognition by D-glucose transport systems of T. brucei trypanosomes and Leishmania are summarized diagrammatically.