A maize gene encoding an NADPH binding enzyme highly homologous to isoflavone reductases is activated in response to sulfur starvation.
we isolated a novel gene that is selectively induced both in roots and shoots in response to sulfur starvation. This gene encodes a cytosolic, monomeric protein of 33 kD that selectively binds NADPH. The predicted polypeptide is highly homologous ( > 70%) to leguminous isoflavone reductases (IFRs), but the maize protein (IRL for isoflavone reductase-like) belongs to a novel family of proteins present in a variety of plants. Anti-IRL antibodies specifically recognize IFR polypeptides, yet the maize protein is unable to use various isoflavonoids as substrates. IRL expression is correlated closely to glutathione availability: it is persistently induced in seedlings whose glutathione content is about fourfold lower than controls, and it is down-regulated rapidly when control levels of glutathione are restored. This glutathione-dependent regulation indicates that maize IRL may play a crucial role in the establishment of a thiol-independent response to oxidative stress under glutathione shortage conditions.
Petrucco
S
S
Institute of Biochemical Sciences, University of Parma, Italy.
Bolchi
A
A
Foroni
C
C
Percudani
R
R
Rossi
G L
GL
Ottonello
S
S
D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D003001:Cloning, Molecular; D003429:Cross Reactions; D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005978:Glutathione / Q000032:analysis; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D015336:Molecular Probe Techniques; D008969:Molecular Sequence Data; D009249:NADP / Q000378:metabolism*; D010088:Oxidoreductases / Q000235:genetics; D044925:Oxidoreductases Acting on CH-CH Group Donors; D010940:Plant Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D018749:RNA, Plant / Q000032:analysis; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013431:Sulfates / Q000378:metabolism; D013455:Sulfur / Q000172:deficiency*; D003313:Zea mays / Q000201:enzymology / Q000235:genetics*
D002352:Carrier Proteins; D018076:DNA, Complementary; C098550:IRL protein, Zea mays; D047908:Intracellular Signaling Peptides and Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D011994:Recombinant Proteins; D013431:Sulfates; D009249:NADP; D013455:Sulfur; D010088:Oxidoreductases; C071072:vestitone reductase; D044925:Oxidoreductases Acting on CH-CH Group Donors; D005978:Glutathione