Toxoplasma gondii Alba proteins are involved in translational control of gene expression

J Mol Biol. 2013 Feb 20. pii: S0022-2836(13)00103-4. doi: 10.1016/j.jmb.2013.01.039. [Epub ahead of print]

Toxoplasma gondii Alba proteins are involved in translational control of gene expression

Gissot M, Walker R, Delhaye S, Alayi TD, Huot L, Hot D, Callebaut I, Schaeffer-Reiss C, Van Dorsselaer A, Tomavo S.

Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM 1019, Université Lille Nord de France, Institut Pasteur de Lille, Lille, France.

Molecular mechanisms controlling gene expression in apicomplexan parasites remain poorly understood. Here, we report the characterisation of two Toxoplasma gondii homologues of the ancient archeal Alba proteins named TgAlba1 and TgAlba2. The targeted disruption of TgAlba1 and 2 genes in both virulent type I and avirulent type II strains of T. gondii reveals that TgAlba proteins may have an important role in regulating stress response. We found that although the steady state level of Tgalba2 transcript is increased in the ΔTgalba1 null mutant parasites, the cognate TgAlba2 protein is undetectable, suggesting that TgAlba1 is required for translation of TgAlba2. Using a Tandem Affinity Purification Tag strategy combined with proteomic analyses, we provide evidence that many factors known to be involved in the translation machinery are co-purified with TgAlba1 and TgAlba2. We further performed RNA pull down and microarray analyses to show that TgAlba1 and 2 bind to more than 30 RNAs including their own transcripts. Moreover, we demonstrate that the tight translational regulation of the TgAlba2 endogenous transcript relies on the presence of both its 3'UTR and that of the TgAlba1 protein. Thus, our findings on TgAlba1 and 2 are consistent with a role in gene-specific translation.

PMID: 23454356 [PubMed - as supplied by publisher]