Doctoral candidate : Nicolas Valette
University / Institution : University of Lorraine
Contract duration — Three years (2015-2018)
Research topic — Functional characterization of fungal small secreted proteins (SSP) related to wood degredation
Research team and supervising scientists —
Research team : Joint Research Unit (UMR) 1136 Tree/Microorganism Interactions (IAM)
PhD supervisor: Eric Gelhaye
PhD co-supervisor: Mélanie Morel-Rouhier
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Context — Wood degradation mechanisms of saprophytic fungi are currently the focus of many research projects, particularly due to the potential impact these microorganisms have in biomass valorization. While most of these studies concern extracellular enzymes, relatively few are concerned with associated mechanisms which enable fungi to resist oxidative and toxic environments resulting from wood degradation. In particular, the first step of the wood breakdown process is the release of aromatic compounds known as extractives which could potentially be toxic for the cells. Interestingly, apart from genes traditionally involved in stress responses, small secreted proteins (SSP) seem to be involved in the cell response to oak molecules. While their exact role has not yet been determined, initial results have clearly shown a relationship exists between wood specificity and SSP secretion.
Objectives and specific questions to be addressed — The main objective of this project is to precisely identify the role SSPs play in fungal physiology (wood modification, cell signaling, stress response and detoxification, etc.) during wood decomposition.
Scientific and socioeconomic issues — We expect that the proposed approach will provide information about how these newly identified proteins participate in the wood degradation process. In the long-term, SSPs could become new targets to optimize degradation efficiency for fungi and developing wood preservation strategies.
Methodological approaches and expected results —A biochemical characterization of the recombinant proteins will be carried out, in particular the screening and identification of putative ligands (wood compounds and proteins). Further resolution of the 3D structure will provide additional information about their functions. Taking a physiological approach will further complete the data by using fluorescent labeling to follow SSP/wood interactions. Moreover, we have developed an efficient method for genetic transformation for Phanerochaete chrysosporium allowing us to follow (at phenotypic and proteomic levels) the effect of overexpression or repression of the SSP of interest.
