Dissecting the mechanisms of copper-azole wood preservatives detoxification by ligninolytic fungi.

Copper-azole based formulations have been widely used to protect wood timbers against fungal decay. While these treatments are efficient for wood protection, leaching of both copper and azoles into the environment has deleterious impact on soils and surface waters. No bioremediation process is currently available for disposable of these wood wastes.

Responses to and detoxification of esculin in white-rot fungi.

Plant metabolites have a great potential for limiting the spread of harmful fungi. However, a better understanding of the mode-of-action of these molecules and the defense systems developed by fungi to resist them, is needed to assess the benefits/risks of using them as antifungal treatment. White-rot fungi are excellent models in this respect, as they have adapted to the hostile habitat that is wood.

Plant polygalacturonase structures specify enzyme dynamics and processivities to fine-tune cell wall pectins.

Polygalacturonases (PGs) fine-tune pectins to modulate cell wall chemistry and mechanics, impacting plant development. The large number of PGs encoded in plant genomes leads to questions on the diversity and specificity of distinct isozymes. Herein, we report the crystal structures of 2 Arabidopsis thaliana PGs, POLYGALACTURONASE LATERAL ROOT (PGLR), and ARABIDOPSIS DEHISCENCE ZONE POLYGALACTURONASE2 (ADPG2), which are coexpressed during root development.

Modes-of-action of antifungal compounds: Stressors and (target-site-specific) toxins, toxicants, or toxin-stressors.

Fungi and antifungal compounds are relevant to the United Nation's Sustainable Development Goals. However, the modes-of-action of antifungals-whether they are naturally occurring substances or anthropogenic fungicides-are often unknown or are misallocated in terms of their mechanistic category. Here, we consider the most effective approaches to identifying whether antifungal substances are cellular stressors, toxins/toxicants (that are target-site-specific), or have a hybrid mode-of-action as toxin-stressors (that induce cellular stress yet are target-site-specific).

Structural insights into the interactions of glutathione transferases with a nitric oxide carrier and sodium nitroprusside.

Glutathione transferases are detoxification enzymes with multifaceted roles, including a role in the metabolism and scavenging of nitric oxide (NO) compounds in cells. Here, we explored the ability of Trametes versicolor glutathione transferases (GSTs) from the Omega class (TvGSTOs) to bind metal-nitrosyl compounds. TvGSTOs have been studied previously for their ligandin role and are interesting models to study protein‒ligand interactions.

Comparative Copper Resistance Strategies of and in a Copper/Azole-Treated Wood Microcosm.

Copper-based formulations of wood preservatives are widely used in industry to protect wood materials from degradation caused by fungi. Wood treated with preservatives generate toxic waste that currently cannot be properly recycled. Despite copper being very efficient as an antifungal agent against most fungi, some species are able to cope with these high metal concentrations.

Diversity of Omega Glutathione Transferases in mushroom-forming fungi revealed by phylogenetic, transcriptomic, biochemical and structural approaches.

The Omega class of glutathione transferases (GSTs) forms a distinct class within the cytosolic GST superfamily because most of them possess a catalytic cysteine residue. The human GST Omega 1 isoform was first characterized twenty years ago, but it took years of work to clarify the roles of the human isoforms. Concerning the kingdom of fungi, little is known about the cellular functions of Omega glutathione transferases (GSTOs), although they are widely represented in some of these organisms.

OSIP1 is a self-assembling DUF3129 protein required to protect fungal cells from toxins and stressors.

Secreted proteins are key players in fungal physiology and cell protection against external stressing agents and antifungals. Oak stress-induced protein 1 (OSIP1) is a fungal-specific protein with unknown function. By using Podospora anserina and Phanerochaete chrysosporium as models, we combined both in vivo functional approaches and biophysical characterization of OSIP1 recombinant protein.

Oxidized glutathione promotes association between eukaryotic translation elongation factor 1Bγ and Ure2p glutathione transferase from Phanerochaete chrysosporium.

The eukaryotic translation elongation factor 1Bγ (eEF1Bγ) is an atypical member of the glutathione transferase (GST) superfamily. Contrary to more classical GSTs having a role in toxic compound detoxification, eEF1Bγ is suggested to act as a scaffold protein, anchoring the elongation factor complex EF1B to the endoplasmic reticulum. In this study, we show that eEF1Bγ from the basidiomycete Phanerochaete chrysosporium is fully active as a glutathione transferase in vitro and undergoes conformational changes upon binding of oxidized glutathione.

Glutathione Transferases: Surrogate Targets for Discovering Biologically Active Compounds.

Glutathione transferases comprise a large class of multifunctional enzymes, some involved in detoxification pathways. Since these enzymes are able to interact with potentially toxic molecules, they could be used as targets to screen for compounds with biological activity. To test this hypothesis, glutathione transferases (GSTs) from the white-rot fungus have been used to screen for antifungal molecules from a library of tropical wood extracts.

Conserved white-rot enzymatic mechanism for wood decay in the Basidiomycota genus Pycnoporus.

White-rot (WR) fungi are pivotal decomposers of dead organic matter in forest ecosystems and typically use a large array of hydrolytic and oxidative enzymes to deconstruct lignocellulose. However, the extent of lignin and cellulose degradation may vary between species and wood type. Here, we combined comparative genomics, transcriptomics and secretome proteomics to identify conserved enzymatic signatures at the onset of wood-decaying activity within the Basidiomycota genus Pycnoporus.

A reverse chemical ecology approach to explore wood natural durability.

The natural durability of wood species, defined as their inherent resistance to wood-destroying agents, is a complex phenomenon depending on many biotic and abiotic factors. Besides the presence of recalcitrant polymers, the presence of compounds with antimicrobial properties is known to be important to explain wood durability. Based on the advancement in our understanding of fungal detoxification systems, a reverse chemical ecology approach was proposed to explore wood natural durability using fungal glutathione transferases.

Target Of Rapamycin pathway in the white-rot fungus Phanerochaete chrysosporium.

The Target Of Rapamycin (TOR) signaling pathway is known to regulate growth in response to nutrient availability and stress in eukaryotic cells. In the present study, we have investigated the TOR pathway in the white-rot fungus Phanerochaete chrysosporium. Inhibition of TOR activity by rapamycin affects conidia germination and hyphal growth highlighting the conserved mechanism of susceptibility to rapamycin.

The structure of Trametes versicolor glutathione transferase Omega 3S bound to its conjugation product glutathionyl-phenethylthiocarbamate reveals plasticity of its active site.

Trametes versicolor glutathione transferase Omega 3S (TvGSTO3S) catalyzes the conjugation of isothiocyanates (ITC) with glutathione (GSH). Previously, this isoform was investigated in depth both biochemically and structurally. Structural analysis of complexes revealed the presence of a GSH binding site (G site) and a deep hydrophobic binding site (H site) able to bind plant polyphenols.

Oak extractive-induced stress reveals the involvement of new enzymes in the early detoxification response of Phanerochaete chrysosporium.

Extensive evidence showed that the efficiency of fungal wood degradation is closely dependent on their ability to cope with the myriad of putative toxic compounds called extractives released during this process. By analysing global gene expression of Phanerochaete chrysosporium after short oak extractive treatment (1, 3 and 6 h), we show that the early molecular response of the fungus concerns first mitochondrial stress rescue followed by the oxidation and finally conjugation of the compounds. During these early responses, the lignolytic degradative system is not induced, rather some small secreted proteins could play an important role in cell protection or signaling.

Trametes versicolor glutathione transferase Xi 3, a dual Cys-GST with catalytic specificities of both Xi and Omega classes.

Glutathione transferases (GSTs) from the Xi and Omega classes have a catalytic cysteine residue, which gives them reductase activities. Until now, they have been assigned distinct substrates. While Xi GSTs specifically reduce glutathionyl-(hydro)quinones, Omega GSTs are specialized in the reduction of glutathionyl-acetophenones.

Molecular recognition of wood polyphenols by phase II detoxification enzymes of the white rot Trametes versicolor.

Wood decay fungi have complex detoxification systems that enable them to cope with secondary metabolites produced by plants. Although the number of genes encoding for glutathione transferases is especially expanded in lignolytic fungi, little is known about their target molecules. In this study, by combining biochemical, enzymatic and structural approaches, interactions between polyphenols and six glutathione transferases from the white-rot fungus Trametes versicolor have been demonstrated.

Enzyme Activities of Two Recombinant Heme-Containing Peroxidases, DyP1 and VP2, Identified from the Secretome of Trametes versicolor.

is a wood-inhabiting agaricomycete known for its ability to cause strong white-rot decay on hardwood and for its high tolerance of phenolic compounds. The goal of the present work was to gain insights into the molecular biology and biochemistry of the heme-including class II and dye-decolorizing peroxidases secreted by this fungus. Proteomic analysis of the secretome of BRFM 1218 grown on oak wood revealed a set of 200 secreted proteins, among which were the dye-decolorizing peroxidase DyP1 and the versatile peroxidase VP2.

Crystal Structure of Saccharomyces cerevisiae ECM4, a Xi-Class Glutathione Transferase that Reacts with Glutathionyl-(hydro)quinones.

Glutathionyl-hydroquinone reductases (GHRs) belong to the recently characterized Xi-class of glutathione transferases (GSTXs) according to unique structural properties and are present in all but animal kingdoms. The GHR ScECM4 from the yeast Saccharomyces cerevisiae has been studied since 1997 when it was found to be potentially involved in cell-wall biosynthesis. Up to now and in spite of biological studies made on this enzyme, its physiological role remains challenging.

Secretion of small proteins is species-specific within Aspergillus sp.

Small secreted proteins (SSP) have been defined as proteins containing a signal peptide and a sequence of less than 300 amino acids. In this analysis, we have compared the secretion pattern of SSPs among eight aspergilli species in the context of plant biomass degradation and have highlighted putative interesting candidates that could be involved in the degradative process or in the strategies developed by fungi to resist the associated stress that could be due to the toxicity of some aromatic compounds or reactive oxygen species released during degradation. Among these candidates, for example, some stress-related superoxide dismutases or some hydrophobic surface binding proteins (HsbA) are specifically secreted according to the species .

The GSTome Reflects the Chemical Environment of White-Rot Fungi.

White-rot fungi possess the unique ability to degrade and mineralize all the different components of wood. In other respects, wood durability, among other factors, is due to the presence of extractives that are potential antimicrobial molecules. To cope with these molecules, wood decay fungi have developed a complex detoxification network including glutathione transferases (GST).

Evolutionary divergence of Ure2pA glutathione transferases in wood degrading fungi.

The intracellular systems of detoxification are crucial for the survival of wood degrading fungi. Within these systems, glutathione transferases could play a major role since this family of enzymes is specifically extended in lignolytic fungi. In particular the Ure2p class represents one third of the total GST number in Phanerochaete chrysosporium.

Characterization of glutathione transferases involved in the pathogenicity of Alternaria brassicicola.

Background: Glutathione transferases (GSTs) represent an extended family of multifunctional proteins involved in detoxification processes and tolerance to oxidative stress. We thus anticipated that some GSTs could play an essential role in the protection of fungal necrotrophs against plant-derived toxic metabolites and reactive oxygen species that accumulate at the host-pathogen interface during infection.

Results: Mining the genome of the necrotrophic Brassica pathogen Alternaria brassicicola for glutathione transferase revealed 23 sequences, 17 of which could be clustered into the main classes previously defined for fungal GSTs and six were 'orphans'.

Glutathionyl-hydroquinone reductases from poplar are plastidial proteins that deglutathionylate both reduced and oxidized glutathionylated quinones.

Glutathionyl-hydroquinone reductases (GHRs) catalyze the deglutathionylation of quinones via a catalytic cysteine. The two GHR genes in the Populus trichocarpa genome, Pt-GHR1 and Pt-GHR2, are primarily expressed in reproductive organs. Both proteins are localized in plastids.

Transcriptomic responses of Phanerochaete chrysosporium to oak acetonic extracts: focus on a new glutathione transferase.

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 the toxicity of these molecules, a transcriptomic analysis of Phanerochaete chrysosporium genes was performed in the presence of oak acetonic extracts. It reveals that in complement to the extracellular machinery of degradation, intracellular antioxidant and detoxification systems contribute to the lignolytic capabilities of fungi, presumably by preventing cellular damages and maintaining fungal health.