Isolation and functional characterization of the PfNT1 nucleoside transporter gene from Plasmodium falciparum

Nicola Carter, Choukri Ben Mamoun, Wei Liu, Edilene O. Silva, Scott Landfear, Daniel E. Goldberg, Buddy Ullman

Research output: Contribution to journalArticle

107 Citations (Scopus)

Abstract

Plasmodium falciparum, the causative agent of the most lethal form of human malaria, is incapable of de novo purine synthesis, and thus, purine acquisition from the host is an indispensable nutritional requirement. This purine salvage process is initiated by the transport of preformed purines into the parasite. We have identified a gene encoding a nucleoside transporter from P. falciparum, PfNT1, and analyzed its function and expression during intraerythrocytic parasite development. PfNT1 predicts a polypeptide of 422 amino acids with 11 transmembrane domains that is homologous to other members of the equilibrative nucleoside transporter family. Southern analysis and BLAST searching of The Institute for Genomic Research (TIGR) malaria data base indicate that PfNT1 is a single copy gene located on chromosome 14. Northern analysis of RNA from intraerythrocytic stages of the parasite demonstrates that PfNT1 is expressed throughout the asexual life cycle but is significantly elevated during the early trophozoite stage. Functional expression of PfNT1 in Xenopus laevis oocytes significantly increases their ability to take up naturally occurring D-adenosine (K(m) = 13.2 μM) and D-inosine (K(m) = 253 μM). Significantly, PfNT1, unlike the mammalian nucleoside transporters, also has the capacity to transport the stereoisomer L-adenosine (K(m) > 500 μM). Inhibition studies with a battery of purine and pyrimidine nucleosides and bases as well as their analogs indicate that PfNT1 exhibits a broad substrate specificity for purine and pyrimidine nucleosides. These data provide compelling evidence that PfNT1 encodes a functional purine/pyrimidine nucleoside transporter whose expression is strongly developmentally regulated in the asexual stages of the P. falciparum life cycle. Moreover, the unusual ability to transport L- adenosine and the vital contribution of purine transport to parasite survival makes PfNT1 an attractive target for therapeutic evaluation.

Original languageEnglish (US)
Pages (from-to)10683-10691
Number of pages9
JournalJournal of Biological Chemistry
Volume275
Issue number14
DOIs
StatePublished - Apr 7 2000

Fingerprint

Nucleoside Transport Proteins
Pyrimidine Nucleosides
Plasmodium falciparum
Purine Nucleosides
Parasites
Genes
Adenosine
Life Cycle Stages
Malaria
Life cycle
Chromosomes, Human, Pair 14
Nutritional Requirements
Inosine
Trophozoites
Purines
Stereoisomerism
Xenopus laevis
Salvaging
Substrate Specificity
Gene encoding

ASJC Scopus subject areas

  • Biochemistry

Cite this

Isolation and functional characterization of the PfNT1 nucleoside transporter gene from Plasmodium falciparum. / Carter, Nicola; Mamoun, Choukri Ben; Liu, Wei; Silva, Edilene O.; Landfear, Scott; Goldberg, Daniel E.; Ullman, Buddy.

In: Journal of Biological Chemistry, Vol. 275, No. 14, 07.04.2000, p. 10683-10691.

Research output: Contribution to journalArticle

Carter, Nicola ; Mamoun, Choukri Ben ; Liu, Wei ; Silva, Edilene O. ; Landfear, Scott ; Goldberg, Daniel E. ; Ullman, Buddy. / Isolation and functional characterization of the PfNT1 nucleoside transporter gene from Plasmodium falciparum. In: Journal of Biological Chemistry. 2000 ; Vol. 275, No. 14. pp. 10683-10691.
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