Emerging function for a glutathione transferase in response to wood extractives toxicity
Résumé
The first steps of wood degradation by fungi lead to the release of toxic compounds known as extractives. To better understand how lignolytic fungi cope with these products, a transcriptomic analysis of Phanerochaete chrysosporium genes was performed in presence of oak acetonic extractives. The most up-regulated genes relate to nutrition, nucleic acid modification, gene regulation, signalling and stress responses. Focusing on the induced antioxidant and detoxification systems, a glutathione transferase of the GTT2 class has been selected for functional characterization. This enzyme does not possess any classical glutathione transferase activity but rather a peroxidase activity. The occurrence of the GTT2 gene within the genome is closely linked to the wood decay capabilities of the fungi. This example suggests that the intracellular detoxification system could have evolved concomitantly with the extracellular ligninolytic machinery in relation to the capacity to degrade wood.