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See detailMécanismes moléculaires associés à l’induction de la pathogénicité chez Streptomyces scabies
Jourdan, Samuel ULg

Doctoral thesis (2016)

Streptomyces are filamentous soil-dwelling bacteria that actively participate in the mineralization of dead organic matter. Members of this bacterial genus are commonly known for the plethora of secondary ... [more ▼]

Streptomyces are filamentous soil-dwelling bacteria that actively participate in the mineralization of dead organic matter. Members of this bacterial genus are commonly known for the plethora of secondary metabolites of interest they secrete. Predominantly saprophytes, some Streptomyces species have been proved to be phytopathogenic. The most widespread and best characterized of these species is Streptomyces scabies which is the causative agent of the common scab disease that affects the underground organs of many plants with a preference for storage organs such as potato tubers or pivot roots (beet, turnip, carrot, etc.). Common scab is characterized by brown and corky lesions on the infected organs and causes significant economic losses around the world. The pathogenicity of S. scabies is directly related to its ability to produce the phytotoxin thaxtomin. Unveiling when, how and why S. scabies triggers the production of its phytotoxin is therefore of major interest to understand phytopathogenicity and the virulence associated with this bacteria. Previous works identified cellobiose as the main elicitor of thaxtomin production. However, no signaling pathway from the sensing of the eliciting signal to the biosynthesis of thaxtomin has been proposed so far. The aim of this work is to elucidate the molecular mechanisms involved in the onset of thaxtomin production in the model species S. scabies. In this work we highlighted the central role of the cellulose utilization transcriptional repressor CebR in S. scabies pathogenicity. Indeed, we showed that this regulator directly controls the expression of thaxtomin biosynthesis genes, but also the expression of genes involved in sensing, transport and catabolism of cellooligosaccharides. Together, our results allow to propose a first signaling pathway from cellooligosaccharide transport to the production of thaxtomin in S. scabies, with each step of the cascade controlled by CebR. The results obtained in the course of this thesis extended well beyond the fundamental research scope of elucidating the mechanisms associated with the onset of virulence of S. scabies. Indeed, assessed if/how our findings could propose solutions to current industrial biotechnology iapplications, i.e. i) to provide a mutant that constitutively produce thaxtomine could improve the production yields of this promising bioherbicide, and ii) to assess the enzymatic characteristics of a Beta-glucosidase of S. scabies as possible candidate in lignocellulose saccharification processes. [less ▲]

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See detailThe CebE/MsiK Transporter is a Doorway to the Cello-oligosaccharide-mediated Induction of Streptomyces scabies Pathogenicity
Jourdan, Samuel ULg; Francis, Isolde; Kim, Min et al

in Scientific Reports (2016)

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See detailThe Cellobiose Sensor CebR is the Gatekeeper of Streptomyces scabies Pathogenicity
Francis, Isolde; Jourdan, Samuel ULg; Fanara, Steven ULg et al

in MBio (2015)

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See detailThe cellobiose-sensor CebR is the gatekeeper of Streptomyces scabies pathogenicity
Jourdan, Samuel ULg; Francis, Isolde; Loria, Rosemary et al

Poster (2014, October)

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See detailUnsuspected Control of Siderophore production by N-acetylglucosamine in Streptomycetes
Craig, Matthias ULg; Lambert, Stéphany ULg; Jourdan, Samuel ULg et al

in Environmental Microbiology Reports (2012)

Detailed reference viewed: 58 (27 ULg)