Survival and infectivity of trypanosomatids rely on cell-surface and secreted
glycoconjugates, many of which contain a variable number of
galactose residues. Incorporation of
galactose to
proteins and
lipids occurs along the secretory pathway from
UDP-galactose (
UDP-Gal). Before being used in glycosylation reactions, however, this activated
sugar donor must first be transported across the endoplasmic reticulum and Golgi membranes by a specific
nucleotide sugar transporter (NST). In this study, we identified an
UDP-Gal transporter (named TcNST2 and encoded by the TcCLB.504085.60 gene) from Trypanosoma cruzi, the etiological agent of
Chagas disease. TcNST2 was identified by heterologous expression of selected putative
nucleotide sugar transporters in a mutant Chinese Hamster Ovary cell line. TcNST2
mRNA levels were detected in all T. cruzi life-cycle forms, with an increase in expression in axenic amastigotes. Confocal microscope analysis indicated that the transporter is specifically localized to the Golgi apparatus. A three-dimensional model of TcNST2 suggested an overall structural conservation as compared with members of the metabolite transporter superfamily and also suggested specific features that could be related to its activity. The identification of this transporter is an important step toward a better understanding of
glycoconjugate biosynthesis and the role NSTs play in this process in trypanosomatids.