Affiliation:
1. Institute for Microbial and Biochemical Technology, USDA Forest Products Laboratory, Madison, Wisconsin 53705
Abstract
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.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
80 articles.
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