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Evolution du génome des Streptomyces : transfert horizontal et variabilité des extrémités chromosomiques

Abstract : Streptomyces are soil dwelling bacteria producers of a considerable number of antibiotic compounds. They exhibit very particular genomic features among bacteria since their chromosomal DNA is linear, among the largest described (8-11 Mb) and with a very high G+C content (70-73%). Partial sequencing and annotation of the Streptomyces ambofaciens chromosome has been undertaken in order to study the genetic organization and evolutionary forces that shape the genome and also to identify new interesting metabolite biosynthesis pathways. Development of bioinformatics methods was the first step of this work and has revealed a genomic compartmentalization where variability is confined in the terminal regions (up to 2 Mb). Comparative genomics between S. ambofaciens and three other Streptomyces species has provided a dynamic view of genome evolution. Exchanges of extremities between linear replicons could be at the origin of intraspecific variability, associating linearity to variability. In addition, terminal regions appear as privileged targets for acquisition of new genetic information resulting from horizontal transfer events. A progressive degeneration of the synteny reveals a gradient of insertion/deletion events which frequency increases toward the chromosomal ends. This mechanism would be the force driving the diversification of Streptomyces and could play a major role in adaptation to the environment.
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Submitted on : Friday, March 30, 2018 - 9:44:29 AM
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  • HAL Id : tel-01754311, version 1
  • PRODINRA : 18751


Frédéric Choulet. Evolution du génome des Streptomyces : transfert horizontal et variabilité des extrémités chromosomiques. Génomique, Transcriptomique et Protéomique [q-bio.GN]. Université Henri Poincaré - Nancy 1, 2006. Français. ⟨NNT : 2006NAN10122⟩. ⟨tel-01754311⟩



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