Functional Diversification of Fungal Glutathione Transferases from the Ure2p Class

Abstract

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.

Transcriptome of an Armillaria root disease pathogen reveals candidate genes involved in host substrate utilization at the host–pathogen interface

“…In addition to Fenton reactions and extracellular peroxidases, aromatic molecules such as lignin can be oxidized by the cytochrome P450 system of enzymes involved in metabolizing exogenous compounds (Thuillier et al. ). Cytochrome P450s comprise a large superfamily of heme‐containing monooxygenases with the greatest diversity of all kingdoms observed among fungi: currently, 2 487 fungal cytochrome P450 species have been identified and assigned to 399 families (see: Ichinose for a review) with an apparently greater diversity among brown‐rot fungi relative to white‐rot fungi (Ide et al.…”

Characterization of a Phanerochaete chrysosporium Glutathione Transferase Reveals a Novel Structural and Functional Class with Ligandin Properties

“…Although some isoforms from the Ure2p, Omega, S-glutathionyl-(chloro)hydroquinone reductase, and GTT have been characterized in yeast (11)(12)(13), Aspergillus sp. (14,15), and Phanerochaete chrysosporium (9,16), the etherase-like class has never been studied to date. Etherase-like GSTs are fungal specific, although they show weak homology with LigE, a bacterial protein responsible for the cleavage of ␤-aryl ether linkages of lignin in Sphingobium sp.…”

Atypical features of a Ure2p glutathione transferase from Phanerochaete chrysosporium

“…PcUre2pB1 was previously described as belonging to the fungal Ure2pB subclass [2]. Almost all considered basidiomycete genomes (98%) possess at least one Ure2pB sequence, suggesting a conserved important function of these proteins in fungal kingdom [1].…”

“…Then, b-ME-SG deglutathionylation tests and dehydroascorbate reductase activity using dehydroascorbate (DHA) as substrate were performed spectrophotometrically in conditions described previously [2]. Deglutathionylation of S-(phenacylacetophenone)-glutathione (PAP-SG) was measured by High Pressure Liquid Chromatography (HPLC) as described previously [6] and influence of oxidized glutathione (GSSG) was assessed by addition of 0 to 6 mM GSSG at fixed PAP-SG and GSH concentrations.…”

“…The Ure2p class has been recently analyzed [2]. It consists of 2 subclasses: Ure2pA, which is extended in saprophytic fungi and Ure2pB, which consists in one or few isoforms per organism [2].…”