TY - JOUR
T1 - Ntdin, a Tobacco Senescence-Associated Gene, is Involved in Molybdenum Cofactor Biosynthesis
AU - Yang, Seung Hwan
AU - Berberich, Thomas
AU - Miyazaki, Atsushi
AU - Sano, Hiroshi
AU - Kusano, Tomonobu
N1 - Funding Information:
We wish to thank the late Akira Watanabe (University of Tokyo), Sunao Yamazaki (Nagasaki University), Ralf Mendel (Technische Uni-versitaet Braunschweig), Kyoichi Koshiba (Tokyo Metropolitan University), Nam-Hai Chua (Rockefeller University), Pius Spielhofer (University of Berne) and Kazuyuki Hiratsuka (Yokohama National University) for supplying the plasmids, N. crassa nit-1 mutant and sincere discussion. We also thank Malcolm Moore for critical reading of this manuscript. This work was supported in part by Grants (RFTF 00L01604) from the Japan Society for Promotion of Science and the Deutsche Forschungsgemeinschaft (grant no. Be 2183/2-1).
PY - 2003/10
Y1 - 2003/10
N2 - To date, dozens of genes have been reported to be up-regulated with senescence in higher plants. Radish din1 and its ortholog sen1 of Arabidopsis are known as such, but their function is not clear yet. Here we have isolated their counterpart cDNA from tobacco and designated it as Ntdin. Its product, Ntdin, a 185 amino acid polypeptide with 56.8% and 54.2% identity to Atsen1 and Rsdin1, respectively, is localized in chloroplasts. Transcripts of Ntdin are induced by sulfate or nitrate but not by phosphate, suggesting its involvement in sulfur and nitrogen metabolism. A database search revealed that Ntdin shows similarity with the C-terminal region of Nicotiana plumbaginifolia Cnx5, which functions in molybdenum cofactor (Moco) biosynthesis. Transgenic tobacco plants with suppressed Ntdin are more tolerant to chlorate, a substrate analog of nitrate reductase, than controls, implying low nitrate reductase activity in the transgenic plants due to a deficiency of Moco. Indeed, enzymatic activities of two molybdoenzymes, nitrate reductase and xanthine dehydrogenase, in transgenic plants are found to be significantly lower than in control plants. Direct measurement of Moco contents reveals that those transgenic plants contain about 5% Moco of those of the control plants. Abscisic acid and indole-3-acidic acid, whose biosynthetic pathways require Moco, up-regulated Ntdin expression. Taken together, it is concluded that Ntdin functions in a certain step in Moco biosynthesis.
AB - To date, dozens of genes have been reported to be up-regulated with senescence in higher plants. Radish din1 and its ortholog sen1 of Arabidopsis are known as such, but their function is not clear yet. Here we have isolated their counterpart cDNA from tobacco and designated it as Ntdin. Its product, Ntdin, a 185 amino acid polypeptide with 56.8% and 54.2% identity to Atsen1 and Rsdin1, respectively, is localized in chloroplasts. Transcripts of Ntdin are induced by sulfate or nitrate but not by phosphate, suggesting its involvement in sulfur and nitrogen metabolism. A database search revealed that Ntdin shows similarity with the C-terminal region of Nicotiana plumbaginifolia Cnx5, which functions in molybdenum cofactor (Moco) biosynthesis. Transgenic tobacco plants with suppressed Ntdin are more tolerant to chlorate, a substrate analog of nitrate reductase, than controls, implying low nitrate reductase activity in the transgenic plants due to a deficiency of Moco. Indeed, enzymatic activities of two molybdoenzymes, nitrate reductase and xanthine dehydrogenase, in transgenic plants are found to be significantly lower than in control plants. Direct measurement of Moco contents reveals that those transgenic plants contain about 5% Moco of those of the control plants. Abscisic acid and indole-3-acidic acid, whose biosynthetic pathways require Moco, up-regulated Ntdin expression. Taken together, it is concluded that Ntdin functions in a certain step in Moco biosynthesis.
KW - Molybdenum cofactor
KW - N. tabacum
KW - Nitrogen
KW - Rhodanese
KW - Senescence
KW - Sulfur
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U2 - 10.1093/pcp/pcg122
DO - 10.1093/pcp/pcg122
M3 - Article
C2 - 14581628
AN - SCOPUS:0242654073
VL - 44
SP - 1037
EP - 1044
JO - Plant and Cell Physiology
JF - Plant and Cell Physiology
SN - 0032-0781
IS - 10
ER -