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.

Glutathione transferases of Phanerochaete chrysosporium: S-glutathionyl-p-hydroquinone reductase belongs to a new structural class.

The white rot fungus Phanerochaete chrysosporium, a saprophytic basidiomycete, possesses a large number of cytosolic glutathione transferases, eight of them showing similarity to the Omega class. PcGSTO1 (subclass I, the bacterial homologs of which were recently proposed, based on their enzymatic function, to constitute a new class of glutathione transferase named S-glutathionyl-(chloro)hydroquinone reductases) and PcGSTO3 (subclass II related to mammalian homologs) have been investigated in this study. Biochemical investigations demonstrate that both enzymes are able to catalyze deglutathionylation reactions thanks to the presence of a catalytic cysteinyl residue.

The fungal glutathione S-transferase system. Evidence of new classes in the wood-degrading basidiomycete Phanerochaete chrysosporium.

The recent release of several basidiomycete genome sequences allows an improvement of the classification of fungal glutathione S-transferases (GSTs). GSTs are well-known detoxification enzymes which can catalyze the conjugation of glutathione to non-polar compounds that contain an electrophilic carbon, nitrogen, or sulfur atom. Following this mechanism, they are able to metabolize drugs, pesticides, and many other xenobiotics and peroxides.