title: A RGG motif protein is involved in Toxoplasma gondii stress-mediated response.
abstract: The molecular mechanisms controlling gene expression are still poorly understood in apicomplexan parasites. Here, we report the characterization of a homolog of the single strand binding proteins (named TgSsossB) in Toxoplasma gondii. We previously showed that TgSsossB interacts with the TgAlba proteins that are involved in translation regulation. We examined the role of TgSsossB in stress-mediated response, and particularly the role of its arginine-glycine-glycine (RGG) repeats domain. TgSsossB recombinant protein is able to bind to single strand DNA and RNA in a sequence-independent manner, but not to double stranded DNA. We showed that the RGG motif is not involved in this ability to bind to nucleic acid. We produced a mutant tagged strain lacking the RGG motif of TgSsossB using the knock-in strategy. We observed that this strain exhibited a fitness defect compared with the parental parasites. Moreover, the mutant strain produced fewer plaques in stress conditions, a defect that is due to a slow growth phenotype when extracellular parasites are exposed to stress. At the molecular level, we showed that the TgSsossB protein lacking a RGG motif lost its ability to interact with TgAlba2 and an isoform of TgAlba1, indicating that the TgAlba complex is likely non-functional in those parasites. Thus, our findings define the RGG domain of TgSsossB as a protein-protein interaction platform and underline the role of the TgAlba-TgSsossB complex in stress-mediated response.
authors.affiliation: Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM 1019, Université Lille Nord de France, Institut Pasteur de Lille, 1 rue du Pr. Calmette, 59 000 Lille, France.
authors.forename: Younes
authors.initials: Y
authors.lastname: Boulila
authors.affiliation: Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM 1019, Université Lille Nord de France, Institut Pasteur de Lille, 1 rue du Pr. Calmette, 59 000 Lille, France.
authors.forename: Stanislas
authors.initials: S
authors.lastname: Tomavo
authors.affiliation: Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM 1019, Université Lille Nord de France, Institut Pasteur de Lille, 1 rue du Pr. Calmette, 59 000 Lille, France. Electronic address: mathieu.gissot@pasteur-lille.fr.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gissot
mesh_terms: D019943:Amino Acid Substitution; D004252:DNA Mutational Analysis; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D013312:Stress, Physiological; D014122:Toxoplasma / Q000254:growth & development / Q000502:physiology*
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D050505:Mutant Proteins; D015800:Protozoan Proteins; D012313:RNA
keywords: Gene expression; RGG motif; Stress; Toxoplasma; Translation