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Dynamique chromosomique et duplication génique chez Streptomyces ambofaciens

Abstract : Gene duplication is a key mechanism for genome evolution and can be very well studied in the bacterium Streptomyces ambofaciens. The dynamics of duplication can be studied thanks to the characterization of the rearrangements in some mutants of the genetic instability of S. ambofaciens. The progeny analysis of mutants carrying a chromosomal fusion showed that this structure initiate a cycle of genomic and genetic instability with gene duplications. A gene duplication located at the chromosomal ends of the linear chromosome was implied in the formation of a genomic rearrangement. The duplicated hasR and hasL genes encode alternative sigma factors belonging to the B. subtilis general stress response sigmaB family factors. The duplication of the has genes in S. ambofaciens is a recent event on a evolutive scale and can result from a genomic rearrangement of genetic instability. Impact of this duplication on the S. ambofaciens specie information was studied by two approaches. The construction of mutants in the order to associate a phenotype with the mutation of one even two copies of the has genes showed that these sigma factors take part in the general stress response. Quantitative transcriptional analysis in single and double has mutant strains revealed that sigmaBR and sigmaBL direct their own transcription as well as that of the duplicate and that other sigma factors take part to this complex regulation network, underlining the redondancy of the sigma factors in Streptomyces.
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Submitted on : Thursday, March 29, 2018 - 11:28:06 AM
Last modification on : Tuesday, March 17, 2020 - 3:16:21 AM
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  • HAL Id : tel-01748193, version 1


Virginie Roth. Dynamique chromosomique et duplication génique chez Streptomyces ambofaciens. Génétique. Université Henri Poincaré - Nancy 1, 2003. Français. ⟨NNT : 2003NAN10228⟩. ⟨tel-01748193⟩



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