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Séminaire

  • Génomes

    • Vendredi 5 février 11:00-12:00 - Jay HINTON - Institute of Integrative Biology, University of Liverpool, UK

      How has Salmonella become so dangerous in Africa ?

      Résumé : With 3.4 million infections each year, invasive non-Typhoidal Salmonella (iNTS) is a major cause of illness worldwide. In Sub-Saharan Africa bloodstream infections with iNTS Salmonella Typhimurium are causing 49,000 deaths annually. Co-infection with HIV or malaria in adults, and a young age (<5 years) are known risk factors. The main causative agent of iNTS is a pathovariant of Salmonella Typhimurium called ST313, which is multi-drug resistant and closely-related to the ST19 variant of Salmonella responsible for gastroenteritis globally.
      Using a combination of comparative genomics and comparative transcriptomics, we discovered phenotypic differences that distinguish African from global Salmonella pathovariants (Canals et al., 2019), and identified a single core genome SNP responsible for the up-regulation of a single promoter that controlled expression of a Salmonella virulence factor (Hammarlöf et al., 2018), and offers part of the explanation of the pan-African epidemic of bloodstream infection.
      All of our Salmonella transcriptomic data are now available online in a user-friendly website that allows comparison of gene expression between African and global pathovariants of
      S. Typhimurium : https://tinyurl.com/SalComD23580
      Most recently, we used thousands of historical and contemporary Salmonella isolates, to understand the precise evolutionary trajectory of the S. Typhimurium ST313 pathogen in Africa. A series of novel genome degradation events impacted upon the function of Salmonella genes required for colonisation of the mammalian gut, providing evidence of niche adaptation and the continuing evolution of ST313 (Pulford et al., 2020).
      I will summarise the evolutionary pathway of invasive S. Typhimurium across Africa, and explain the value of an integrated functional genomic analysis for understanding how bacterial pathogens cause disease.
      References : Canals et al. (2019) PLoS Biology 10.1371/journal.pbio.3000059
      Hammarlöf et al. (2018). PNAS DOI : 10.1073/pnas.1714718115
      Pulford et al. (2020) Nature Microbiology DOI:10.1038/s41564-020-00836-1
      Contact : Nara Figueroa Bossi <nara.figueroa i2bc.paris-saclay.fr>
      and
      Lionello Bossi <lionello.bossi i2bc.paris-saclay.fr>

      Lieu : Visio

      Article

    • Vendredi 12 février 10:00-11:00 - Masato Kanemaki - National Institute of Genetics

      Controlling protein expression by using the power of plants

      Résumé : Genetic perturbation is a powerful way to analyze the function of proteins in living cells. For this purpose, we pioneered to develop the auxin-inducible degron (AID) technology by which a degron-fused protein can be rapidly degraded after the addition of the plant hormone auxin (Nishimura et al., Nat. Methods, 2009). By combining with CRISPR-based genome editing, it was possible to generate AID conditional mutants of human cells (Natsume et al., Cell Reports, 2016). The AID system became one of the popular genetic tools to study the function of proteins. However, leaky degradation and high doses of auxin for inducing degradation have been major drawbacks. Moreover, nobody has successfully applied the AID system to control protein degradation in living mice. We recently overcame these problems by taking advantage of chemical biology and successfully established the AID2 system (Yesbolatova et al. Nat. Comm, 2020). By using AID2, we can now sharply control protein degradation in yeast, mammalian cells and mice.

      Lieu : Visio

      Article

    • Vendredi 26 février 11:00-12:00 - Sebastian Baumgarten - Pasteur Institute

      Resolving m6A-mediated post-transcriptional control in the human malaria parasite

      Résumé : Post-transcriptional regulation of gene expression is central to the development and replication of the malaria parasite, Plasmodium falciparum, within its human host. The timely coordination of RNA maturation, homeostasis and protein synthesis relies on the recruitment of specific RNA-binding proteins to their cognate target mRNAs. Our work focuses on the role of RNA modifications as one possible mediator of such mRNA-protein interactions. Using mass spectrometry and different RNA sequencing approaches, we identified N6-methylation of adenosines (m6A) as the most highly abundant and developmentally regulated mRNA modification, exceeding m6A levels known in any other eukaryote. Combining targeted genome editing, RNA protein-pulldowns and interaction proteomics, we characterized the m6A methyltransferase ‘writer’, and ‘reader’ complex that effect m6A-medited post-transcriptional control, thereby revealing a role for m6A in mediating transcript stability and translational efficiency. Our recent work has laid the foundation to interrogate this extensive epitranscriptomic program in this unicellular eukaryote, with our current focus laying on elucidating its role in fine-tuning the transcriptional cascade throughout the parasite’s lifecycle.
      Invited by Joana.Santos i2bc.paris-saclay.fr

      Lieu : visio

      Article

  • Microbiologie

    • Mardi 2 février 11:30-12:30 - Thomas Rey - Société De Sangosse - collaborateur de l'équipe "Microbiologie moléculaire des Actinomycètes"

      Investigating the genomic and metabolomic features enabling plant rhizosphere colonisation by Streptomyces violaceusniger sp. AgN23

      Lieu : VisioLien Visio disponible sur l’intranet ou sur demande (seminaires@i2bc.paris-saclay.fr)

      Article

    • Mardi 9 février 11:30-12:30 - François Guerin - CHU de Rennes

      Exemples de mécanismes moléculaires d’adaptation du complexe Enterobacter cloacae à son environnement

      Lieu : Visio - Lien Visio disponible sur l’intranet ou sur demande (seminaires i2bc.paris-saclay.fr)

      Article

  • cytoskeleton club

    • Mardi 9 février 11:30-13:00 - Helgo Schmidt - IGBMC, Strasbourg

      Cytoskeleton club - Structural Investigations on the Molecular Machines Dynein and Rea

      Résumé : The microtubule motor dynein and the ribosome maturation factor Rea1 consist each of around 5000 amino-acid residues and belong to the AAA+ (ATPases associated with various cellular activities) protein family of molecular machines. They share key architectural features like a concatenated ring of six AAA+ domains featuring a large “linker domain” extension. ATP hydrolysis in the AAA+ ring drives the remodelling of the linker domain, which allows dynein and Rea1 to fulfil their respective biological function. These structural and mechanistic similarities set dynein and Rea1 apart from the rest of the large AAA+ field.
      My team is interested in studying the molecular mechanisms of dynein and Rea1 by cryoEM and x-ray crystallography. In this talk, I will present the structural insights we obtained about their modes of operation. I will especially focus on the events within these molecular machines that link ATP-hydrolysis in the AAA+ ring to the remodelling of the linker to produce force for the movement along microtubules and removal of assembly factors from maturing ribosomal particles.

      Lieu : Webinar

      Article

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