title: A dual-targeted aminoacyl-tRNA synthetase in Plasmodium falciparum charges cytosolic and apicoplast tRNACys.
abstract: Plasmodium parasites possess two endosymbiotic organelles: a mitochondrion and a relict plastid called the apicoplast. To accommodate the translational requirements of these organelles in addition to its cytosolic translation apparatus, the parasite must maintain a supply of charged tRNA molecules in each of these compartments. In the present study we investigate how the parasite manages these translational requirements for charged tRNACys with only a single gene for CysRS (cysteinyl-tRNA synthetase). We demonstrate that the single PfCysRS (Plasmodium falciparum CysRS) transcript is alternatively spliced, and, using a combination of endogenous and heterologous tagging experiments in both P. falciparum and Toxoplasma gondii, we show that CysRS isoforms traffic to the cytosol and apicoplast. PfCysRS can recognize and charge the eukaryotic tRNACys encoded by the Plasmodium nucleus as well as the bacterial-type tRNA encoded by the apicoplast genome, albeit with a preference for the eukaryotic type cytosolic tRNA. The results of the present study indicate that apicomplexan parasites have lost their original plastidic cysteinyl-tRNA synthetase, and have replaced it with a dual-targeted eukaryotic type CysRS that recognizes plastid and nuclear tRNACys. Inhibitors of the Plasmodium dual-targeted CysRS would potentially offer a therapy capable of the desirable immediate effects on parasite growth as well as the irreversibility of inhibitors that disrupt apicoplast inheritance.
authors.affiliation: *Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia.
authors.forename: James S
authors.initials: JS
authors.lastname: Pham
authors.affiliation: †Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, U.S.A.
authors.forename: Reiko
authors.initials: R
authors.lastname: Sakaguchi
authors.forename: Lee M
authors.initials: LM
authors.lastname: Yeoh
authors.affiliation: *Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia.
authors.forename: Nilushi S
authors.initials: NS
authors.lastname: De Silva
authors.affiliation: ‡School of Botany, The University of Melbourne, Melbourne, VIC 3010, Australia.
authors.forename: Geoffrey I
authors.initials: GI
authors.lastname: McFadden
authors.affiliation: †Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, U.S.A.
authors.forename: Ya-Ming
authors.initials: YM
authors.lastname: Hou
authors.affiliation: *Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Ralph
mesh_terms: D017398:Alternative Splicing; D000604:Amino Acyl-tRNA Synthetases / Q000235:genetics / Q000378:metabolism*; D063546:Apicoplasts / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D009154:Mutation; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D021381:Protein Transport; D013696:Temperature; D014122:Toxoplasma / Q000235:genetics
chemical_list: D029968:Escherichia coli Proteins; D007527:Isoenzymes; D049452:Green Fluorescent Proteins; D000604:Amino Acyl-tRNA Synthetases; C019975:cysteinyl-tRNA synthetase