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Diversité, dynamique et mobilité des éléments intégratifs conjugatifs (ICE) de Streptococcus agalactiae intégrés dans l'extrémité 3' du gène codant un ARNt Lysine

Abstract : Integrative and Conjugative Elements (ICEs) and related elements are widespread in bacteria and play a key role in horizontal gene transfer. ICEs excise by site-specific recombination as a circular intermediate, promote their own transfer by conjugation and then integrate into a replicon of the recipient cell. Streptococcus agalactiae is an opportunistic pathogen that causes severe human invasive neonatal infections as well as infections in animals (bovine, fish...). Previous in silico analysis of eight sequenced genomes of S. agalactiae identified in each genome a different element integrated in the tRNALys CTT gene with four putative ICEs. This study, carried on 246 other genomes of S. agalactiae, confirmed the prevalence and diversity of elements integrated in this locus with 98% of the strains carrying an element (ICE, trans or cis mobilizable elements composite elements...). A novel family of putative mobilisable elements which can integrate in the oriT of ICE has been characterized. Functional analysis of 5 ICEs demonstrated that four can excise of the chromosome but that only ICE_FSLS3-026_tRNALys and ICE_515_tRNALys can transfer by conjugation inside the species or to S. pyogenes for one of them. Composite elements have been obtained after transfer of ICE_515_tRNALys to a recipient strain already carrying an element integrated in the same locus. One of this composite element is able to excise and transfer by conjugation to a new strain leading to cis-mobilization of the resident element. In conclusion, ICEs and cis and trans mobilizable elements are widespread in S. agalactiae and contribute to the genomic plasticity in this bacterial species
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Submitted on : Thursday, March 29, 2018 - 12:38:53 PM
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  • HAL Id : tel-01750136, version 1

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Aurore Puymège. Diversité, dynamique et mobilité des éléments intégratifs conjugatifs (ICE) de Streptococcus agalactiae intégrés dans l'extrémité 3' du gène codant un ARNt Lysine. Génomique, Transcriptomique et Protéomique [q-bio.GN]. Université de Lorraine, 2013. Français. ⟨NNT : 2013LORR0147⟩. ⟨tel-01750136⟩

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