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Reference : UMR8227-SOPLAB-013
Workplace : ROSCOFF
Date of publication : Monday, September 09, 2019
Scientific Responsible name : MIRJAM CZJZEK
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 November 2019
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Brown algae are large biomass producers in coastal regions. This biomass is dominated by cell wall polysaccharides which are crucial in algal physiology. The main polymers are the alginates and the fucose-containing sulfated polysaccharides (FCSPs), including fucans. Alginates are used as texturing agent in the food industry while the FCSPs have extensive interest in biomedical applications. Despite this importance, virtually nothing is known about the biosynthesis of cell wall polysaccharides in brown algae. Glycosyltransferases (GTs) are key enzymes involved in glycan biosynthesis. In eukaryotes most of the GTs are localized in the Golgi apparatus or at the plasma membrane. In brown algae the first genome sequence released in 2010, allowed us to reconstruct the putative routes for the biosynthesis of cell wall polysaccharides. Candidate GTs genes were suggested for the synthesis of sulfated fucans and alginates, likely localized in distinct organelles. Yet the candidate genes are still highly speculative and none of them has been purified and/or cloned to date in brown algae. This PhD project aims to functionally characterize brown algal GTs for the very first time. A multidisciplinary strategy will be used from gene analyses (bioinformatics) to protein isolation (native GTs and recombinant GTs) and activity screening (preparation of acceptor/donor molecules, assays using conventional techniques such as those based on radiolabeled sugars).
The PhD will be supervised by Mirjam Czjzek and Cécile Hervé within the Marine Glycobiology group from UMR8227. The project aims to explore the biosynthetic routes for major cell wall components in brown algae, with notably the subcellular location and functional characterization of specific enzymatic activities.
The PhD candidate will have to take in charge of its own lab cultures of the brown alga Saccharina latissima, to tackle and use a protocol for organelles fractionation in S. latissima, with a special focus on the Golgi apparatus, to perform the bioinformatics studies to identify all the GT families in transcriptomics/genomics data from brown algae, to produce and purify the recombinant GTs, to assay the GT activity tests, and to integrate and write down all the results in a comprehensive format.
• strong skills in analytical chemistry of carbohydrates and in the biochemistry of proteins ; good knowledge in molecular biology
• Experience in organelle extraction and in protein biochemistry
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