Characterization of a nuclear pore protein sheds light on the roles and composition of the Toxoplasma gondii nuclear pore complex

• Published in: Cellular and molecular life sciences : CMLS 2017-06, Vol.74 (11), p.2107-2125
• Main Authors: Courjol, Flavie, Mouveaux, Thomas, Lesage, Kevin, Saliou, Jean-Michel, Werkmeister, Elisabeth, Bonabaud, Maurine, Rohmer, Marine, Slomianny, Christian, Lafont, Franck, Gissot, Mathieu
• Format: Article
• Language: English
• Subjects: Animals; Biochemistry; Biomedical and Life Sciences; Biomedicine; Cell Biology; Cell Nucleus - metabolism; Chromatin; CRISPR-Cas Systems; Cytoplasm; Eukaryotes; eukaryotic cells; Exports; Fluorescence; Fluorescence in situ hybridization; Gene Expression Regulation; Gene Knockdown Techniques; High-Throughput Nucleotide Sequencing; Immunoprecipitation; Life Sciences; Light; Localization; mammals; Mass spectrometry; Mass spectroscopy; messenger RNA; Microbiology and Parasitology; Microscopy; mutants; nuclear membrane; Nuclear Pore - metabolism; Nuclear Pore Complex Proteins - metabolism; Nuclear transport; Nuclei; nucleoporins; Original; Original Article; Parasites; Parasites - metabolism; Parasitology; Phenotype; precipitin tests; Protein Binding; Protein Transport; Proteins; Protozoan Proteins - metabolism; Ribonucleic acid; RNA; RNA Transport; RNA, Ribosomal, 18S - metabolism; Toxoplasma - growth & development; Toxoplasma - metabolism; Toxoplasma gondii; Transcription; Transport
• ISSN: 1420-682X; 1420-9071
• DOI: 10.1007/s00018-017-2459-3

The nuclear pore is a key structure in eukaryotes regulating nuclear-cytoplasmic transport as well as a wide range of cellular processes. Here, we report the characterization of the first Toxoplasma gondii nuclear pore protein, named TgNup302, which appears to be the orthologue of the mammalian Nup98-96 protein. We produced a conditional knock-down mutant that expresses TgNup302 under the control of an inducible tetracycline-regulated promoter. Under ATc treatment, a substantial decrease of TgNup302 protein in inducible knock-down (iKD) parasites was observed, causing a delay in parasite proliferation. Moreover, the nuclear protein TgENO2 was trapped in the cytoplasm of ATc-treated mutants, suggesting that TgNup302 is involved in nuclear transport. Fluorescence in situ hybridization revealed that TgNup302 is essential for 18S RNA export from the nucleus to the cytoplasm, while global mRNA export remains unchanged. Using an affinity tag purification combined with mass spectrometry, we identified additional components of the nuclear pore complex, including proteins potentially interacting with chromatin. Furthermore, reverse immunoprecipitation confirmed their interaction with TgNup302, and structured illuminated microscopy confirmed the NPC localization of some of the TgNup302-interacting proteins. Intriguingly, facilitates chromatin transcription complex (FACT) components were identified, suggesting the existence of an NPC-chromatin interaction in T. gondii . Identification of TgNup302-interacting proteins also provides the first glimpse at the NPC structure in Apicomplexa, suggesting a structural conservation of the NPC components between distant eukaryotes.