Reference : UMR5798-CHRGRA-001
Workplace : TALENCE
Date of publication : Wednesday, May 25, 2022
Scientific Responsible name : Christine Grauby-Heywang
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
In bacteria, the control and the maintenance of the cellular shape is closely associated to different fundamental cellular processes such as division and adaptation to environmental conditions. The characterization of mechanisms associated with shape control could help, consequently, to understand and control different processes including bacteria resistance to mechanical or chemical stresses. In this context, the overall goal of our project is the reproduction of complex shapes in minimal cells to better understand morphogenesis mechanisms.
In most bacteria, the peptidoglycan wall plays a prominent role in determining the cellular shape. The main role of this wall hides the internal cytoskeleton's one, making difficult the determination of the impact of cytoskeleton in these bacteria. In this context, Spiroplasma is a bacterial model devoid of wall, giving us a unique opportunity to understand the role of internal cytoskeleton on cellular shape in the absence of wall. This model is characterized by a helical shape maintained only thanks to its internal cytoskeleton, this last one being mainly made of proteins homologous of eukaryotic actin. However, how spiroplasmas adopt and maintain their helical shape without the assistance of an external cell wall remains largely elusive, notably because of the lack of efficient genetic tools to obtain mutants deficient for specific protein production. This limitation motivates us to develop an alternative strategy based on the expression or insertion of different combinations of proteins in appropriate heterologous complementary systems: 1) a non-helical mycoplasma, which is also devoid of a cell wall but can be efficiently genetically engineered; 2) biomimetic liposomes produced by a microfluidic approach.
The PhD student will be more particularly involved in the first axis of the project, since he/she will produce mycoplasmas expressing various combinations of spiroplasma cytoskeleton proteins. He/she will also study these systems in terms of morphology, protein localization in cells and membrane properties. The partners involved in this project bring complementary competences in microbiology, genomic engineering, biochemistry, high resolution fluorescence microscopy and atomic force microscopy.
The candidate will be mainly integrated in the « Biophysics and Nanosystems” group of the “Soft Matter and Biophysics” team of LOMA and in the “Biophysics and biochemistry of Mollicutes” group in the “Mollicutes” team of UMR 1332 BFP. He/she will work daily with members of these teams (researchers, technical staff, students).
Constraints and risks
The candidate will share his/her time between two laboratories of the University of Bordeaux (BFP, LOMA) according to the project progress. He/she will also perform some missions in MMSB (Lyon).
We talk about it on Twitter!