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6 septembre 2019: 1 événement

  • Département Biochimie, Biophysique et Biologie Structurale

    Vendredi 6 septembre 11:00-12:00 - Tomio Takahashi - Equipe Biologie Cellulaire des Archées, I2BC

    Identification of new topoisomerase and topoisomerase-like proteins in mobile genetic elements

    Résumé : The control of DNA topology by DNA topoisomerases is essential for fundamental cellular processes, such as transcription and replication. These enzymes, ubiquitous and essential for every organism, exist as several non-homologous families. We previously identified a small group of atypical type IIB DNA topoisomerases, called Topo VIII, mainly encoded by free or integrated plasmids from bacteria. Taking advantage of the rapid expansion of sequenced genomes, we found new putative Topo VIII sequences. Further analysis confirm and expand the presence of the corresponding genes in mobile genetic elements across nine different bacterial phyla and one archaeal superphylum. We notably identified a new subfamily of enzymes called "Mini-A" in free and integrated bacterioviruses and archaeoviruses, that are homologous but distantly related to other type IIB topoisomerases. Interestingly, one uncharacterized peptide at the C-terminal extremity of type IIB enzymes seems sufficient to discriminate between the three subfamilies, Mini-A, Topo VI and Topo VIII. This "Type 2 topoisomerases Interaction" T2I box could be one key element to understand the difference between these subfamilies. Altogether, this work leads to an updated model for the origin and evolution of type IIB topoisomerase family and raise questions concerning the function of topoisomerases for mobile genetic elements.

    Lieu : Salle de conférence - Bat 144, Campus CEA Saclay

    En savoir plus : Département Biochimie, Biophysique et Biologie Structurale