First published online November 17, 2006; 10.1104/pp.106.091330
Plant Physiology 143:530-539 (2007)
© 2007 American Society of Plant Biologists
OPEN ACCESS ARTICLE
SYSTEMS BIOLOGY, MOLECULAR BIOLOGY, AND GENE REGULATION
Tobacco Isoenzyme 1 of NAD(H)-Dependent Glutamate Dehydrogenase Catabolizes Glutamate in Vivo[OA]
Matthew Peter Purnell1 and
José Ramon Botella*
Department of Botany, School of Integrative Biology, University of Queensland, Queensland 4072, Australia
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 GDH  - (isoenzyme 1) or  - (isoenzyme 7) subunits, as well as another five - isoenzyme permutations. To clarify the in vivo direction of the reaction catalyzed by GDH isoenzyme 1, [15N]Glu was supplied to roots of two independent transgenic tobacco (Nicotiana tabacum) lines with increased isoenzyme 1 levels (S4-H and S49-H). The [15N]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.
1 Present address: Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, c/o BSES Limited, 50 Meiers Road, Indooroopilly, QLD 4068, Australia.
The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: José Ramon Botella (j.botella{at}uq.edu.au).
[OA] Open Access articles can be viewed online without a subscription.
www.plantphysiol.org/cgi/doi/10.1104/pp.106.091330
* Corresponding author; e-mail j.botella{at}uq.edu.au; fax 61–7–3365–1699.
Received October 15, 2006;
accepted November 3, 2006;
published November 17, 2006.
This article has been cited by other articles:
|
|
|
|
 
Y. Trusov, W. Zhang, S. M. Assmann, and J. R. Botella
G{gamma}1 + G{gamma}2 != G{beta}: Heterotrimeric G Protein G{gamma}-Deficient Mutants Do Not Recapitulate All Phenotypes of G{beta}-Deficient Mutants
Plant Physiology,
June 1, 2008;
147(2):
636 - 649.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
Y. Miyashita and A. G. Good
NAD(H)-dependent glutamate dehydrogenase is essential for the survival of Arabidopsis thaliana during dark-induced carbon starvation
J. Exp. Bot.,
February 21, 2008;
(2008)
erm340v1.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
D. S. Skopelitis, N. V. Paranychianakis, A. Kouvarakis, A. Spyros, E. G. Stephanou, and K. A. Roubelakis-Angelakis
The Isoenzyme 7 of Tobacco NAD(H)-Dependent Glutamate Dehydrogenase Exhibits High Deaminating and Low Aminating Activities in Vivo
Plant Physiology,
December 1, 2007;
145(4):
1726 - 1734.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
B. G. Forde and P. J. Lea
Glutamate in plants: metabolism, regulation, and signalling
J. Exp. Bot.,
July 1, 2007;
58(9):
2339 - 2358.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
Y. Trusov, J. E. Rookes, K. Tilbrook, D. Chakravorty, M. G. Mason, D. Anderson, J.-G. Chen, A. M. Jones, and J. R. Botella
Heterotrimeric G Protein {gamma} Subunits Provide Functional Selectivity in G{beta}{gamma} Dimer Signaling in Arabidopsis
PLANT CELL,
April 1, 2007;
19(4):
1235 - 1250.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
