An NADH:Quinone Oxidoreductase Active during Biodegradation by the Brown-Rot Basidiomycete Gloeophyllum trabeum

Abstract

The brown-rot basidiomycete Gloeophyllum trabeum uses a quinone redox cycle to generate extracellular Fenton reagent, a key component of the biodegradative system expressed by this highly destructive wood decay fungus. The hitherto uncharacterized quinone reductase that drives this cycle is a potential target for inhibitors of wood decay. We have identified the major quinone reductase expressed by G. trabeum under conditions that elicit high levels of quinone redox cycling. The enzyme comprises two identical 22-kDa subunits, each with one molecule of flavin mononucleotide. It is specific for NADH as the reductant and uses the quinones produced by G. trabeum (2,5-dimethoxy-1,4-benzoquinone and 4,5-dimethoxy-1,2-benzoquinone) as electron acceptors. The affinity of the reductase for these quinones is so high that precise kinetic parameters were not obtainable, but it is clear that k cat /K m for the quinones is greater than 10 8 M ؊1 s ؊1 . The reductase is encoded by a gene with substantial similarity to NAD(P)H:quinone reductase genes from other fungi. The G. trabeum quinone reductase may function in quinone detoxification, a role often proposed for these enzymes, but we hypothesize that the fungus has recruited it to drive extracellular oxyradical production.

Tenebrionid secretions and a fungal benzoquinone oxidoreductase form competing components of an arms race between a host and pathogen

“…BbBqrA clustered relatively far from orthologous proteins in the brownand white-rot basidiomycetes, G. trabeum and P. chrysosporium, whose quinone reductases have been implicated in lignin biodegradation processes. Unlike these enzymes, however, B. bassiana BbBqrA does not contain a 5′-putative leader sequence for protein secretion (37,39). The secreted enzymes target cross-linked quinones present in extracellular lignin substrates (70).…”

“…The pathway involves the induction of NAD (P)H:quinone reductases, which catalyze the conversion of cytotoxic benzoquinone to (nontoxic) hydroquinone. Several quinone reductases have been purified and characterized and their genes cloned in both white-and brown-rot fungi (basidiomycetes) as part of lignin degradation pathways (37)(38)(39)(40). However, entomopathogenic fungi are incapable of lignin degradation, and no information is available regarding the presence and/or function of these enzymes in this group of fungi.…”

Fenton Reaction Driven by Iron Ligands

“…The Fenton reaction driven by DHB has been studied in different systems like metabolic pathways in biological systems (95)(96)(97) and advanced oxidation process (AOPs) to water or wastewater treatment (76,89,98,99) . This phenomenon has been explained by several authors through distinct reaction pathways: (I) DHBs can form complexes with Fe 3+ and then reduce it to Fe 2+ (100) .…”

Electrosorption for organic pollutants removal and desalination by graphite and activated carbon fiber composite electrodes

“…From the six possible electrochemical effects on the electrode surface for organic matter removal, the biodegradability improvement might be explained by the capacitive ion storage in the electrical double layer or Faradaic reactions on the electrode surface (Porada et al 2013b). The capacitive ion storage could effectively capture the polar organic molecule in the double layer, and the Faradaic reaction could be quinone into hydroquinone, which is easier for biodegradation (Jensen et al 2002). In this research, the author did not observe the hydroquinone formation or organics polarity change due to the complexity and high concentration of organic molecules in the real black liquor from refined cotton wastewater.…”