TY - JOUR
T1 - Molecular and functional characterization of the first nucleobase transporter gene from African trypanosomes
AU - Henriques, Cristina
AU - Sanchez, Marco A.
AU - Tryon, Rob
AU - Landfear, Scott M.
N1 - Funding Information:
This work was supported by Grants AI44138 and AI25920 from the National Institutes of Health and by a postdoctoral fellowship from the Conselho Nacional de Desenvolvimento Cientifico e Technológico, CNPq Brazil, (to C.H.). S.M.L. is a Burroughs Wellcome Molecular Parasitology Scholar. We would like to thank Aurelie Snyder for performing the fluorescence microscopy and Jay Bangs for a gift of the pXS2 expression vector.
PY - 2003/8/31
Y1 - 2003/8/31
N2 - African trypanosomes are unable to synthesize purines and depend upon purine nucleoside and nucleobase transporters to salvage these compounds from their hosts. To understand the crucial role of purine salvage in the survival of these parasites, a central objective is to identify and characterize all of the purine permeases that mediate uptake of these essential nutrients. We have cloned and functionally expressed in a purine nucleobase transport deficient strain of Saccharomyces cerevisiae a novel nucleobase transporter gene, TbNT8.1, from Trypanosoma brucei. The permease encoded by this gene mediates the uptake of hypoxanthine, adenine, guanine, and xanthine with Kms in the low micromolar range. The TbNT8.1 protein is a member of the equilibrative nucleoside transporter (ENT) family of permeases that occur in organisms as diverse as protozoa and mammals. TbNT8.1 is distinct from other ENT permeases that have been identified in trypanosomes in utilizing multiple purine nucleobases, rather than purine nucleosides, as substrates and is hence the first bona fide nucleobase permease identified in these parasites. Furthermore, unlike the mRNAs for other purine transporters, TbNT8.1 mRNA is significantly more abundant in insect stage procyclic forms than in mammalian stage bloodstream forms, and the TbNT8.1 permease thus may represent a major route for purine nucleobase uptake in procyclic trypanosomes.
AB - African trypanosomes are unable to synthesize purines and depend upon purine nucleoside and nucleobase transporters to salvage these compounds from their hosts. To understand the crucial role of purine salvage in the survival of these parasites, a central objective is to identify and characterize all of the purine permeases that mediate uptake of these essential nutrients. We have cloned and functionally expressed in a purine nucleobase transport deficient strain of Saccharomyces cerevisiae a novel nucleobase transporter gene, TbNT8.1, from Trypanosoma brucei. The permease encoded by this gene mediates the uptake of hypoxanthine, adenine, guanine, and xanthine with Kms in the low micromolar range. The TbNT8.1 protein is a member of the equilibrative nucleoside transporter (ENT) family of permeases that occur in organisms as diverse as protozoa and mammals. TbNT8.1 is distinct from other ENT permeases that have been identified in trypanosomes in utilizing multiple purine nucleobases, rather than purine nucleosides, as substrates and is hence the first bona fide nucleobase permease identified in these parasites. Furthermore, unlike the mRNAs for other purine transporters, TbNT8.1 mRNA is significantly more abundant in insect stage procyclic forms than in mammalian stage bloodstream forms, and the TbNT8.1 permease thus may represent a major route for purine nucleobase uptake in procyclic trypanosomes.
KW - African trypanosomes
KW - Heterologous expression in yeast
KW - Nucleobase transporter
KW - Purine salvage
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U2 - 10.1016/S0166-6851(03)00167-1
DO - 10.1016/S0166-6851(03)00167-1
M3 - Article
C2 - 12946846
AN - SCOPUS:0142106996
SN - 0166-6851
VL - 130
SP - 101
EP - 110
JO - Molecular and Biochemical Parasitology
JF - Molecular and Biochemical Parasitology
IS - 2
ER -