title: Assembly of the novel five-component apicomplexan multi-aminoacyl-tRNA synthetase complex is driven by the hybrid scaffold protein Tg-p43.
abstract: In Toxoplasma gondii, as in other eukaryotes, a subset of the amino-acyl-tRNA synthetases are arranged into an abundant cytoplasmic multi-aminoacyl-tRNA synthetase (MARS) complex. Through a series of genetic pull-down assays, we have identified the enzymes of this complex as: methionyl-, glutaminyl-, glutamyl-, and tyrosyl-tRNA synthetases, and we show that the N-terminal GST-like domain of a partially disordered hybrid scaffold protein, Tg-p43, is sufficient for assembly of the intact complex. Our gel filtration studies revealed significant heterogeneity in the size and composition of isolated MARS complexes. By targeting the tyrosyl-tRNA synthetases subunit, which was found exclusively in the complete 1 MDa complex, we were able to directly visualize MARS particles in the electron microscope. Image analyses of the negative stain data revealed the observed heterogeneity and instability of these complexes to be driven by the intrinsic flexibility of the domain arrangements within the MARS complex. These studies provide unique insights into the assembly of these ubiquitous but poorly understood eukaryotic complexes.
authors.affiliation: European Molecular Biology Laboratory, Grenoble, France ; CNRS, UMR5163, LAPM, Grenoble, France ; Université Joseph Fourier, Grenoble, France.
authors.forename: Jason M
authors.initials: JM
authors.lastname: van Rooyen
authors.affiliation: CNRS, UMR5163, LAPM, Grenoble, France ; Université Joseph Fourier, Grenoble, France.
authors.forename: Jean-Benjamin
authors.initials: JB
authors.lastname: Murat
authors.affiliation: CNRS, UMR5163, LAPM, Grenoble, France ; Université Joseph Fourier, Grenoble, France.
authors.forename: Pierre-Mehdi
authors.initials: PM
authors.lastname: Hammoudi
authors.affiliation: CEA, IRTSV, Laboratoire Biologie à Grande Echelle, Grenoble, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Kieffer-Jaquinod
authors.affiliation: CEA, IRTSV, Laboratoire Biologie à Grande Echelle, Grenoble, France.
authors.forename: Yohann
authors.initials: Y
authors.lastname: Coute
authors.affiliation: Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Sharma
authors.affiliation: CNRS, UMR5163, LAPM, Grenoble, France ; Université Joseph Fourier, Grenoble, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Pelloux
authors.affiliation: European Molecular Biology Laboratory, Grenoble, France.
authors.forename: Hassan
authors.initials: H
authors.lastname: Belrhali
authors.affiliation: CNRS, UMR5163, LAPM, Grenoble, France ; Université Joseph Fourier, Grenoble, France.
authors.forename: Mohamed-Ali
authors.initials: MA
authors.lastname: Hakimi
mesh_terms: D000595:Amino Acid Sequence; D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002850:Chromatography, Gel; D002942:Circular Dichroism; D003593:Cytoplasm / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D047468:Immunoprecipitation; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015996:Survival Rate; D014122:Toxoplasma / Q000201:enzymology / Q000472:pathogenicity; D014123:Toxoplasmosis / Q000382:microbiology* / Q000401:mortality / Q000473:pathology
chemical_list: D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C087692:SAG3 protein, Toxoplasma gondii; D000604:Amino Acyl-tRNA Synthetases