Tobacco isoenzyme 1 of NAD(H)-dependent glutamate dehydrogenase catabolizes glutamate in vivo

Purnell, M. P. and Botella, J. R. (2007) Tobacco isoenzyme 1 of NAD(H)-dependent glutamate dehydrogenase catabolizes glutamate in vivo. Plant Physiology, 143 1: 530-539. doi:10.1104/pp.106.091330


Author Purnell, M. P.
Botella, J. R.
Title Tobacco isoenzyme 1 of NAD(H)-dependent glutamate dehydrogenase catabolizes glutamate in vivo
Journal name Plant Physiology   Check publisher's open access policy
ISSN 0032-0889
Publication date 2007-01-01
Year available 2006
Sub-type Article (original research)
DOI 10.1104/pp.106.091330
Open Access Status PMC
Volume 143
Issue 1
Start page 530
End page 539
Total pages 10
Editor Ort, D. R.
Long, J.
Place of publication Rockville, USA
Publisher American Society of Plant Biologists
Language eng
Subject C1
270400 Botany
620000 - Plant Production and Plant Primary Products
Abstract Glutamate (Glu) dehydrogenase (GDH, EC 1.4.1.2 - 1.4.1.4) catalyzes in vitro the reversible amination of 2-oxoglutarate to Glu. The in vivo direction(s) of the GDH reaction in higher plants and hence the role(s) of this enzyme is unclear, a situation confounded by the existence of isoenzymes comprised totally of either GDHb-beta (isoenzyme 1) or alpha-(isoenzyme 7) subunits, as well as another five alpha-beta isoenzyme permutations. To clarify the in vivo direction of the reaction catalyzed by GDH isoenzyme 1, [N-15] Glu was supplied to roots of two independent transgenic tobacco (Nicotiana tabacum) lines with increased isoenzyme 1 levels (S4-H and S49-H). The [N-15] ammonium(NH4+) accumulation rate in these lines was elevated approximately 65% compared with a null segregant control line, indicating that isoenzyme 1 catabolizes Glu in roots. Leaf glutamine synthetase (GS) was inhibited with a GS-specific herbicide to quantify any contribution by GDH toward photorespiratory NH4+ reassimilation. Transgenic line S49-H did not show enhanced resistance to the herbicide, indicating that the large pool of isoenzyme 1 in S49-H leaves was unable to compensate for GS and suggesting that isoenzyme 1 does not assimilate NH4+ in vivo.
Keyword Plant Sciences
Nuclear-magnetic-resonance
Cell-suspension Cultures
Nicotiana-plumbaginifolia
Nitrogen Assimilation
Arabidopsis-thaliana
Subcellular-localization
Leaf Senescence
Null Mutant
Zea-mays
Plants
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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Created: Tue, 19 Feb 2008, 02:01:28 EST