Description du sujet de thèse

Towards a comprehensive understanding of reaction mechanisms of « Lytic polysaccharide monooxygénases » (LPMO) for an optimized hydrolysis of recalcitrant lignocellulose substrates
Biofuels are one of the solutions for reducing the combustion of fossil fuels and global greenhouse gas emissions. Second generation bioethanol is produced from lignocellulosic substrates which are not in competition with food production, but the economic viability of the process depends on an efficient enzymatic hydrolysis. The Trichoderma reesei enzymatic cocktail is one of the most efficient, but certain substrates, such as softwood or Miscanthus, remain difficult to degrade with a low sugar yield. To improve the enzymatic mix, LPMOs (Lytic Polysaccharide Monooxygenases) are particularly interesting targets thanks to their capacity of boosting cellulase activity. However, their activity is highly dependent on operating conditions which hampers their industrial implementation.
The present PhD project is part of the project Integrated approach on copper systems to improve recalcitrant polysaccharide utilization (PuLCO) which is financed by ANR in the frame of the Priority Research Program and Equipment (PEPR) B-BEST. Its goal is to improve the understanding of the structure-function relationship and the catalytic mechanism of LPMO, in order to allow an efficient industrial implementation. In particular, the mechanisms of the reduction of the active-site copper ion and the ROS (reactive oxygen species) generation, as well as the interaction with the substrate will be studied.
The thesis aims to identify important structural features of LPMO which influence their reactivities towards cellulose and their interaction with the substrate. To this end, variants of previously described enzymes will be generated and the effect of mutations on substrate affinity, reactivity, impact on interaction with co-substrates and electron donors will be studied under various conditions. Moreover, the impact on synergy with cellulases in the presence of biomass substrate under industrial conditions will be evaluated.
In addition, the variants will also be characterized by partner laboratories of the PuLCO project with expertise in biophysical methods, such as NMR, electrochemistry and EPR (electron paramagnetic resonance) as well as in theoretical modelling. This multidisciplinary approach, combining fundamental and applied aspects, will thus allow gathering complementary data to acquire essential knowledge on LPMO which is key for improvement of LPMO for industrial processes.

Keywords : cellulose hydrolysis, biofuel, cellulases, LPMO, enzymology, metalloenzyme, Pichia pastoris, Trichoderma reesei

Competences required :
Master's degree in biology or biochemistry. The candidate should have very good theoretical and practical knowledge of biochemical methods and enzymology. Basic knowledge of structural biology and biophysical methods are desirable. Fluency in English. Basic knowledge of French would be a plus.
Soft skills : Team work, communication skills, curiosity

Contexte de travail

This work will be carried out as part of a project funded by France 2030 and PEPR B-BEST (PuLCO; ANR-24-PEBB-0009) involving 5 research groups bringing together interdisciplinary expertise ranging from experimental to theoretical approaches. The PhD candidate will be based at IFPEN in Rueil Malmaison, and will be co-directed by Senta Heiss Blanquet (IFPEN, Rueil) and Jalila Simaan (iSm2, Marseille). IFPEN has extensive experience in the valorization of lignocellulosic biomass and enzymatic cocktails.

The candidate will be paid and will work at IFPEN (Rueil-Malmaison). Note that the CNRS will not be the employer.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

Knowledge of chemical and biological hazards is essential. The candidate must be familiar with good laboratory practice.

Informations complémentaires

The candidate will be developing his/her research at IFPEN in Rueil-Malmaison.
For further information, contact:
senta.blanquet@ifpen.fr
simon.arragain@ifpen.fr