Functional Diversification of Fungal Glutathione Transferases from the Ure2p Class

The glutathione-S-transferase (GST) proteins represent an extended family involved in detoxification processes. They are divided into various classes with high diversity in various organisms. The Ure2p class is especially expanded in saprophytic fungi compared to other fungi. This class is subdivided into two subclasses named Ure2pA and Ure2pB, which have rapidly diversified among fungal phyla. We have focused our analysis on Basidiomycetes and used Phanerochaete chrysosporium as a model to correlate the sequence diversity with the functional diversity of these glutathione transferases. The results show that among the nine isoforms found in P. chrysosporium, two belonging to Ure2pA subclass are exclusively expressed at the transcriptional level in presence of polycyclic aromatic compounds. Moreover, we have highlighted differential catalytic activities and substrate specificities between Ure2pA and Ure2pB isoforms. This diversity of sequence and function suggests that fungal Ure2p sequences have evolved rapidly in response to environmental constraints

Reactive Oxygen Species in phanerochaete chrysosporium relationship between extracellular oxidative and intracellular antioxidant systems

Chapter 6International audienceThe basidiomycete Phanerochaete chrysosporium is a model of ligninolytic fungus which has been studied for a long time. The lignin degradation mediated by this fungus occurs through oxidative processes involving a large set of extracellular enzymes including lignin oxidases and lignin-degrading auxiliary enzymes. In this context, the production of reactive oxygen species (ROS) by this fungus occurs in physiological conditions, that is, during the wood degradation. Ligninolytic basidiomycetes have thus had to develop strategies to protect themselves against oxidative damages induced during lignin oxidation. The excretion of extracellular ligninolytic enzymes is indeed linked at least partially to the fungal intracellular redox state, suggesting a relationship between the intracellular antioxidant system and the production of extracellular ROS by this fungus. This review describes the extracellular systems involved in ROS production, the intracellular systems protecting against ROS, as well as the relationship between them