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L'évolution des phages tempérés d'entérobactéries

Abstract : The integration and degradation of viruses (or phages) constitute a genetic influx of genes within bacterial genomes (then named prophages). This process is thought to promote bacterial diversification. The mechanisms promoting the evolutionary impact of prophages on their hosts remain poorly understood. The first part of my thesis focused on the adaptation of prophages to the genetic and structural organization of the chromosome of Escherichia and Salmonella. These results showed a strong conservation of prophage integration positions and different adaptations of prophages to the chromosome organization of their hosts. In a second study, I focused on the mechanisms of genetic diversification of phages. The study of lambdoid phages revealed the existence of two recombination strategies among these phages: using the host recombination system RecBCD through the presence of Chi sites or using their own recombination system. This work suggests that using one or the other recombination strategy has an important impact on the genomic diversification and mosaicism of these phages. Finally, by detecting and analyzing vertically inherited prophages within their host genomes, I showed that many degraded prophages are conserved and evolve under purifying selection. This suggests that many prophages are potentially domesticated by bacteria. Altogether, these analyses are improving our understanding of the contribution of prophages to the genetic diversification of their hosts.
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Submitted on : Monday, October 27, 2014 - 2:52:14 PM
Last modification on : Thursday, April 7, 2022 - 10:10:21 AM
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  • HAL Id : tel-01077952, version 1


Louis-Marie Bobay. L'évolution des phages tempérés d'entérobactéries. Biologie cellulaire. Université Pierre et Marie Curie - Paris VI, 2014. Français. ⟨NNT : 2014PA066154⟩. ⟨tel-01077952⟩



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