title: Purine restriction induces pronounced translational upregulation of the NT1 adenosine/pyrimidine nucleoside transporter in Leishmania major.
abstract: Leishmania and other parasitic protozoa are unable to synthesize purines de novo and are reliant upon purine nucleoside and nucleobase transporters to import preformed purines from their hosts. To study the roles of the four purine permeases NT1-NT4 in Leishmania major, null mutants in each transporter gene were prepared and the effect of each gene deletion on purine uptake was monitored. Deletion of the NT3 purine nucleobase transporter gene or both NT3 and the NT2 nucleoside transporter gene resulted in pronounced upregulation of adenosine and uridine uptake mediated by the NT1 permease and also induced up to a 200-fold enhancement in the level of the NT1 protein but not mRNA. A similar level of upregulation of NT1 was achieved in wild-type promastigotes that were transferred to medium deficient in purines. Pulse labelling and treatment of cells with the translation inhibitor cycloheximide revealed that control of NT1 expression occurs primarily at the level of translation and not protein turnover. These observations imply the existence of a translational control mechanism that enhances the ability of Leishmania parasites to import essential purines when they are present at limiting concentrations.
authors.affiliation: Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, USA.
authors.forename: Diana
authors.initials: D
authors.lastname: Ortiz
authors.forename: Raquel
authors.initials: R
authors.lastname: Valdés
authors.forename: Marco A
authors.initials: MA
authors.lastname: Sanchez
authors.forename: Johanna
authors.initials: J
authors.lastname: Hayenga
authors.forename: Carolyn
authors.initials: C
authors.lastname: Elya
authors.forename: Siegfried
authors.initials: S
authors.lastname: Detke
authors.forename: Scott M
authors.initials: SM
authors.lastname: Landfear
mesh_terms: D000241:Adenosine / Q000378:metabolism*; D017353:Gene Deletion; D005786:Gene Expression Regulation; D018320:Leishmania major / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D014176:Protein Biosynthesis; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D014529:Uridine / Q000378:metabolism
chemical_list: D026901:Membrane Transport Proteins; C520652:NT1 adenosine permease, Leishmania; D015800:Protozoan Proteins; D000241:Adenosine; D014529:Uridine