ATTENTION !! SEMINAIRE ANNULE !!! Integrons, Antibiotics, SOS response and Horizontal gene transfers : intimate connections

Orateur : Didier MAZEL (Unité Plasticité du Génome Bactérien, Institut Pasteur, Paris)

If integrons are mainly known as the genetic agents responsible for the capture and spread of antibiotic resistance determinants among Gram-negative pathogens, they are also are found in the genomes of hundreds of environmental bacterial species. In particular, all Vibrio genomes sequenced so far have been found to carry a sedentary integron platform. We reported a direct link between this gene capture system and the SOS response, a regulatory network induced by DNA damage, which is known to promote genetic variation in time of stress. We showed that LexA controls the expression of most integron integrases and that SOS induction increases the recombination of gene cassettes. We have now found that horizontal gene transfer mechanisms (conjugation and natural transformation) and most antibiotics induce the SOS response in Vibrio cholerae, and certainly in most Vibrio species. This coupling enhances the potential for cassette swapping and capture in cells undergoing stress, while freezing the cassette arrangement in steady environments. We will discuss how these discoveries sponsor integrons as integrated adaptive systems for these bacteria.

Télécharger dans mon agenda