FQR1, a novel primary auxin-response gene, encodes a flavin mononucleotide-binding quinone reductase.
FQR1 is a novel primary auxin-response gene that codes for a flavin mononucleotide-binding flavodoxin-like quinone reductase. Accumulation of FQR1 mRNA begins within 10 min of indole-3-acetic acid application and reaches a maximum of approximately 10-fold induction 30 min after treatment. This increase in FQR1 mRNA abundance is not diminished by the protein synthesis inhibitor cycloheximide, demonstrating that FQR1 is a primary auxin-response gene. Sequence analysis reveals that FQR1 belongs to a family of flavin mononucleotide-binding quinone reductases. Partially purified His-tagged FQR1 isolated from Escherichia coli catalyzes the transfer of electrons from NADH and NADPH to several substrates and exhibits in vitro quinone reductase activity. Overexpression of FQR1 in plants leads to increased levels of FQR1 protein and quinone reductase activity, indicating that FQR1 functions as a quinone reductase in vivo. In mammalian systems, glutathione S-transferases and quinone reductases are classified as phase II detoxification enzymes. We hypothesize that the auxin-inducible glutathione S-transferases and quinone reductases found in plants also act as detoxification enzymes, possibly to protect against auxin-induced oxidative stress.
Laskowski
Marta J
MJ
Department of Biology, Williams College, Williamstown, MA 01267, USA. mlaskowski@williams.edu
Dreher
Kate A
KA
Gehring
Mary A
MA
Abel
Steffen
S
Gensler
Arminda L
AL
Sussex
Ian M
IM
D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004579:Electron Transport; D004926:Escherichia coli / Q000235:genetics; D005486:Flavin Mononucleotide / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008969:Molecular Sequence Data; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics* / Q000378:metabolism; D009252:NADPH Dehydrogenase / Q000378:metabolism; D010936:Plant Extracts / Q000378:metabolism; D030821:Plants, Genetically Modified; D011808:Quinone Reductases / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D010936:Plant Extracts; D012333:RNA, Messenger; D005486:Flavin Mononucleotide; D003513:Cycloheximide; D016660:NAD(P)H Dehydrogenase (Quinone); C457770:FQR1 protein, Arabidopsis; D011808:Quinone Reductases; D009252:NADPH Dehydrogenase