New substrates and activity of Phanerochaete chrysosporium Omega glutathione transferases.

Omega glutathione transferases (GSTO) constitute a family of proteins with variable distribution throughout living organisms. It is notably expanded in several fungi and particularly in the wood-degrading fungus Phanerochaete chrysosporium, raising questions concerning the function(s) and potential redundancy of these enzymes. Within the fungal families, GSTOs have been poorly studied and their functions remain rather sketchy.

Characterization of a Phanerochaete chrysosporium glutathione transferase reveals a novel structural and functional class with ligandin properties.

Glutathione S-transferases (GSTs) form a superfamily of multifunctional proteins with essential roles in cellular detoxification processes. A new fungal specific class of GST has been highlighted by genomic approaches. The biochemical and structural characterization of one isoform of this class in Phanerochaete chrysosporium revealed original properties.

Affinity chromatography: a valuable strategy to isolate substrates of methionine sulfoxide reductases?

Reactive oxygen species fulfill key roles in development and signaling, but lead at high concentration to damage in macromolecules. In proteins, methionine (Met) is particularly prone to oxidative modification and can be oxidized into Met sulfoxide (MetO). MetO reduction is catalyzed by specialized enzymes, termed methionine sulfoxide reductases (MSRs), involved in senescence and protection against diseases and environmental constraints.

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.