Description of the thesis topic

Siderophores are metabolites produced by many microorganisms to meet their requirements in iron. Thanks to their metal-chelating properties and their ability to be specifically transported by bacteria, siderophores hold strong biotechnological potential, particularly in biomedicine. The project aims to produce, through bacterial engineering, analogues of the siderophore pyoverdine—the main siderophore produced by Pseudomonas aeruginosa—in order to broaden its applications. More specifically, the goal is to modify the biosynthetic pathway of pyoverdine, a peptide synthesized by megasynthases, so as to incorporate non-canonical amino acids (doi: 10.1186/s12934-024-02472-4). The strategy relies on enzymatic engineering of one of these megasynthases, through a rational design approach, to alter its substrate specificity and generate variants capable of incorporating functionalized amino acids. The ultimate objective is to create strains producing functionalized pyoverdine, which can then be conjugated to different molecules (for example, antibiotics) to develop targeted vectors or to explore new properties of the siderophore.
In this context, the recruited candidate will develop an in vitro screening system designed to measure the catalytic activity of the megasynthase and its variants, construct the strains required for the production of pyoverdine analogues, and participate in bioconjugation experiments, as well as in the purification and characterization (mass spectrometry) of the obtained analogues and conjugates.
The recruited candidate is expected to:
• Possess solid knowledge in biochemistry, particularly in the production (cell-based and cell-free systems) and purification (by chromatography) of proteins and biomolecules, in enzymology, as well as in analytical methods such as mass spectrometry. Skills in molecular biology (cloning, bacterial genome editing) and microbiology are also expected.
• Be able to interact with the different project partners and work effectively in a multidisciplinary environment.
• Contribute to the technical life of the laboratory alongside other staff (ordering, equipment maintenance, stock and waste management).
• Communicate their work effectively in both written and spoken French and English.

Work Context

The PhD will take place at the Laboratory of Biotechnology and Cell Signaling (BSC – UMR 7242), located at the École Supérieure de Biotechnologie de Strasbourg (ESBS) in Illkirch. The doctoral candidate will join the team Metals and Microorganisms: Biology, Chemistry and Applications, co-directed by Dr. I. Schalk and Dr. G. Mislin. The team is composed of 25 members (permanent staff, PhD students, and postdoctoral researchers) working at the interface of biology and chemistry. With more than 160 publications since 2001, the team is internationally recognized for its contribution to elucidating siderophore-dependent iron acquisition systems in bacteria. The recruited candidate will be enrolled in the Doctoral School of Life and Health Sciences (ED414) at the University of Strasbourg. The project is funded by the French National Research Agency (ANR) and involves five partners: the BSC – UMR7242 laboratory, the IGBMC (UMR7104) and TBI (INSA Toulouse) for molecular modeling, as well as the LSMIS (UMR7140) and LIMA (UMR7042) for the physicochemical characterization of siderophores.

Constraints and risks

Work will involve handling microorganisms in a BSL-1 laboratory (non-pathogenic strains) and in a BSL-2 laboratory for class 2 pathogenic microorganisms (Pseudomonas aeruginosa).