Functional characterization of fungal small secreted proteins in relation to wood degradation.

PI : Mélanie Morel-Rouhier  (UMR 1136 Joint Research Unit for Tree/Microorganism Interactions – IAM)

Co-applicants : S. Dumarçay (LERMAB)

Collaboration : Thomas Guillemette (Université d’Angers)

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Context — Wood degradation mechanisms by saprophytic fungi are currently the focus of many research projects, especially because of the potential of these microorganisms in biomass valorization. While most of the studies concern the extracellular enzymes, very few concern the associated mechanisms, which enable fungi to resist to the oxidative and toxic environment arising from wood degradation. In particular, the first step of wood breakdown is the release of aromatic compounds known as extractives, which could be toxic for the cells. Interestingly, beside the classical genes involved in stress responses, small secreted proteins (SSP) seem to be involved in the cell response to oak molecules. Their exact role has not been determined yet however, first results clearly showed a relationship between wood specificity and secretion of SSP.

Objectives — The main objective of this project is to precise the role of SSP in fungal physiology (wood modification, cell signaling, stress response or detoxification….) during wood decomposition.

Approach —  A biochemical characterization of the recombinant proteins will be carried out, in particular the screening and identification of putative ligands (wood compounds and proteins). The further resolution of the 3D structure of the complex will give additional information on their functions. A physiological approach will complete these data by using fluorescent labeling to follow SSP/wood interactions. Moreover, we have developed an efficient method of genetic transformation for Phanerochaete chrysosporium allowing to follow, at phenotypic and proteomic levels, the effect of the overexpression or repression of the SSP of interest.

Expected results and impacts —We are expecting the proposed approach to provide information about the role of these proteins newly identified as participating in the wood degradation process. In a long-term perspective, SSP could be new targets for optimizing the degradation efficiency of fungi and wood preservation strategies.