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Master Thesis

L'absence d'une protéine impliquée dans le maintien de la polarité chez la bactérie Gram-négatif Caulobacter crescentus induit une sensibilité à la vancomycine

Abstract : Caulobacter crescentus is a Gram-negative bacterium from the Alphaproteobacteria class which give rise to two daughter cells at each cell cycle on which we can observe either a pilus on the swarmer cell or an anchor on the stalked cell. The localisation of these organelles is driven by a large number of proteins including the TipN localization protein which also plays a role in chromosomal segregation. By studying this protein, a suprising new function has been highlighted. The wild type strain (WT) is naturally resistant to nalidixic acid (Nal) thanks to a single nucleotide polymorphism on the Nal target gene. However the strain without the gene tipN (∆tipN) is sensitive to this antibiotic. Experiments showed that the induction of the expression of an efflux pump, or compounds of the pump, are sufficient for the strain to be sensitive to Nal. A large chemical screening has been done in order to find other molecules that act like Nal and the screening highlighted the vancomycin. This results was surprising because this large antibiotic don’t cross the outer membrane of Gram-negative bacteria and it is use in human medicine to treat Gram-positive infections. This study aims to understand how vancomycin is active on our model Caulobacter crescentus mutated, and we will show that a) Nal and vancomycin do not use the same pathway for being toxic and b) those antibiotics seems to use a structural default of the membrane to induce their effects.
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Master Thesis
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https://dumas.ccsd.cnrs.fr/dumas-02285424
Contributor : Jean-Hugues Morneau <>
Submitted on : Thursday, September 19, 2019 - 12:03:41 PM
Last modification on : Wednesday, July 15, 2020 - 8:56:03 AM
Long-term archiving on: : Saturday, February 8, 2020 - 6:32:16 AM

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  • HAL Id : dumas-02285424, version 1

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Simon-Ulysse Robert Vallet. L'absence d'une protéine impliquée dans le maintien de la polarité chez la bactérie Gram-négatif Caulobacter crescentus induit une sensibilité à la vancomycine. Sciences pharmaceutiques. 2019. ⟨dumas-02285424⟩

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