Séminaires Génomes
Les événements du département Biologie des Génomes sont affichés en rouge dans l’agenda I2BC...
Contact : Yoshiharu YAMAICHI
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Vendredi 22 janvier 10:00-11:00 - Masayuki Su'etsugu - Rikkyo University In vitro amplification of mega-sized circular DNA and its applications Résumé : We have reconstituted an entire replication cycle of the Escherichia coli circular chromosome with 26 proteins that catalyze initiation, fork progression, Okazaki-fragment maturation, and decatenation. Because decatenation provides supercoiled monomers that are competent for the next round of replication initiation, the cycle repeats autonomously and continuously. This Replication-Cycle Reaction (RCR) can propagate large circular DNA up to 1 Mbp. We further developed a multiple-DNA fragment assembly reaction, termed RA (Recombination Assembly). Using a two-step enzymatic reaction, RA-RCR, we have successfully constructed a 27 kb plasmid from 50 fragments. RA-RCR thus provides a powerful cell-free tool to generate large circular DNA without relying on conventional cell-based cloning.
Contact : Yoshiharu.YAMAICHI
Lieu : Visio
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Vendredi 29 janvier 11:00-12:00 - Anjana Badrinarayanan - National Centre for Biological Sciences (TIFR), Bangalore, India Searching for homology : in vivo mechanism of bacterial homologous recombination Résumé : Structural Maintenance of Chromosome (SMC) proteins play central roles in chromosome dynamics across domains of life. While their function in chromosome organization and segregation in bacteria is well-characterized, their contribution to pathways of genome integrity maintenance is less understood. Here, I will present recent work from my group showing evidence for requirement of the highly conserved SMC protein, RecN, in mediating homology search and repair in vivo during double-strand break (DSB) repair. Using quantitative live cell imaging, we follow temporal and spatial dynamics of the recombinase, RecA, after induction of a single DSB on the chromosome of Caulobacter crescentus. We find that the RecA-nucleoprotein filament is mobile and moves in a directional manner across the length of the cell, undergoing several such cycles until homology search is complete. These dynamics are independent of the presence of a repair template. Instead, such large-scale translocations of the filament as well as remodeling of its architecture is driven by RecN. We show that filament dynamics is lost in the absence of RecN. Rates of RecA loading or integrity of the RecA-nucleoprotein filament are unaffected in the absence of RecN. Together, our data suggest that RecN arrives after RecA has loaded at the break, following which it triggers RecA filament mobility via its ATPase cycle. Our findings are consistent with a model where symmetry breaking by RecN likely acts as the driver for directional RecA filament translocation. Such symmetry breaking highlights a conserved feature of SMC proteins across domains of life, irrespective of their specific functions in modulating chromosome dynamics.
Contact : Yoshiharu.YAMAICHI i2bc.paris-saclay.frLieu : Visio
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Vendredi 5 février 11:00-12:00 - Prof. Jay HINTON - Institute of Integrative Biology, University of Liverpool, UK Séminaire Jay HINTON Résumé :
Contact : Lionello.BOSSI et Nara.FIGUEROA-BOSSI
Lieu : Visio
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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
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Lundi 22 mars 16:00-17:00 - Xindan Wang - Indiana University Title to be announced Résumé : Invited by Christophe Possoz.
Due to the time difference, the seminar will be exceptionally held at 16h00 (11h00 EDT)Lieu : Visio
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Vendredi 16 avril 11:00-12:00 - Jose Antonio ESCUDERO - Universidad Complutense de Madrid Evolutionary History of Integrons Résumé : Abstract to be announced.
Invited by Virginia Lioy Lioy <virginia.lioy i2bc.paris-saclay.fr>Lieu : visio
