title: Plasmodial aspartyl-tRNA synthetases and peculiarities in Plasmodium falciparum.
abstract: Distinctive features of aspartyl-transfer RNA (tRNA) synthetases (AspRS) from the protozoan Plasmodium genus are described. These apicomplexan AspRSs contain 29-31 amino acid insertions in their anticodon binding domains, a remarkably long N-terminal appendix that varies in size from 110 to 165 amino acids and two potential initiation codons. This article focuses on the atypical functional and structural properties of Plasmodium falciparum cytosolic AspRS, the causative parasite of human malaria. This species encodes a 626 or 577 amino acids AspRS depending on whether initiation starts on the first or second in-frame initiation codon. The longer protein has poor solubility and a propensity to aggregate. Production of the short version was favored as shown by the comparison of the recombinant protein with endogenous AspRS. Comparison of the tRNA aminoacylation activity of wild-type and mutant parasite AspRSs with those of yeast and human AspRSs revealed unique properties. The N-terminal extension contains a motif that provides unexpectedly strong RNA binding to plasmodial AspRS. Furthermore, experiments demonstrated the requirement of the plasmodial insertion for AspRS dimerization and, therefore, tRNA aminoacylation and other putative functions. Implications for the parasite biology are proposed. These data provide a robust background for unraveling the precise functional properties of the parasite AspRS and for developing novel lead compounds against malaria, targeting its idiosyncratic domains.
authors.affiliation: Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg Cedex, France.
authors.forename: Tania
authors.initials: T
authors.lastname: Bour
authors.forename: Aziza
authors.initials: A
authors.lastname: Akaddar
authors.forename: Bernard
authors.initials: B
authors.lastname: Lorber
authors.forename: Sébastien
authors.initials: S
authors.lastname: Blais
authors.forename: Christian
authors.initials: C
authors.lastname: Balg
authors.forename: Ermanno
authors.initials: E
authors.lastname: Candolfi
authors.forename: Magali
authors.initials: M
authors.lastname: Frugier
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D001226:Aspartate-tRNA Ligase / Q000378:metabolism*; D001224:Aspartic Acid / Q000737:chemistry; D001483:Base Sequence; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D019281:Dimerization; D005656:Fungal Proteins / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D000596:Amino Acids; D005656:Fungal Proteins; D001224:Aspartic Acid; D001226:Aspartate-tRNA Ligase