Plant Physiol. Tips for Better Browsing
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Web of Science (31)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ortega, J. L.
Right arrow Articles by Sengupta-Gopalan, C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ortega, J. L.
Right arrow Articles by Sengupta-Gopalan, C.
Agricola
Right arrow Articles by Ortega, J. L.
Right arrow Articles by Sengupta-Gopalan, C.

Oxidative Turnover of Soybean Root Glutamine Synthetase. In Vitro and in Vivo Studies1

Jose Luis Ortega, Dominique Roche2, and Champa Sengupta-Gopalan*

Agronomy and Horticulture Department, New Mexico State University, Las Cruces, New Mexico 88003

Glutamine synthetase (GS) is the key enzyme in ammonia assimilation and catalyzes the ATP-dependent condensation of NH3 with glutamate to produce glutamine. GS in plants is an octameric enzyme. Recent work from our laboratory suggests that GS activity in plants may be regulated at the level of protein turnover (S.J. Temple, T.J. Knight, P.J. Unkefer, C. Sengupta-Gopalan [1993] Mol Gen Genet 236: 315-325; S.J. Temple, S. Kunjibettu, D. Roche, C. Sengupta-Gopalan [1996] Plant Physiol 112: 1723-1733; S.J. Temple, C. Sengupta-Gopalan [1997] In C.H. Foyer, W.P. Quick, eds, A Molecular Approach to Primary Metabolism in Higher Plants. Taylor & Francis, London, pp 155-177). Oxidative modification of GS has been implicated as the first step in the turnover of GS in bacteria. By incubating soybean (Glycine max) root extract enriched in GS in a metal-catalyzed oxidation system to produce the ·OH radical, we have shown that GS is oxidized and that oxidized GS is inactive and more susceptible to degradation than nonoxidized GS. Histidine and cysteine protect GS from metal-catalyzed inactivation, indicating that oxidation modifies the GS active site and that cysteine and histidine residues are the site of modification. Similarly, ATP and particularly ATP/glutamate give the enzyme the greatest protection against oxidative inactivation. The roots of plants fed ammonium nitrate showed a 3-fold increase in the level of GS polypeptides and activity compared with plants not fed ammonium nitrate but without a corresponding increase in the GS transcript level. This would suggest either translational or posttranslational control of GS levels.

1   This work was supported by U.S. Department of Agriculture grant no. 9237305-7941 and by the Agricultural Experiment Station at New Mexico State University, Las Cruces.
2   Present address: U.S. Department of Agriculture-Agricultural Research Service, Tifton, GA 31793.
*   Corresponding author; e-mail csgopala{at}nmsu.edu; fax 1-505-646-6041.

Plant Physiol. (1999) 119: 1483-1496
Copyright Clearance Center:   0032-0889/99/119//14
© 1999 American Society of Plant Physiologists




This article has been cited by other articles:


Home page
 J Exp BotHome page
L. Lima, A. Seabra, P. Melo, J. Cullimore, and H. Carvalho
Post-translational regulation of cytosolic glutamine synthetase of Medicago truncatula
J. Exp. Bot., August 1, 2006; 57(11): 2751 - 2761.
[Abstract] [Full Text] [PDF]

Home page
 J Exp BotHome page
J. Hancock, R. Desikan, J. Harrison, J. Bright, R. Hooley, and S. Neill
Doing the unexpected: proteins involved in hydrogen peroxide perception
J. Exp. Bot., May 1, 2006; 57(8): 1711 - 1718.
[Abstract] [Full Text] [PDF]

Home page
 Plant Physiol.Home page
J. Harrison, M.-A. Pou de Crescenzo, O. Sene, and B. Hirel
Does Lowering Glutamine Synthetase Activity in Nodules Modify Nitrogen Metabolism and Growth of Lotus japonicus?
Plant Physiology, September 1, 2003; 133(1): 253 - 262.
[Abstract] [Full Text] [PDF]

Home page
 Plant Physiol.Home page
K. J. Morey, J. L. Ortega, and C. Sengupta-Gopalan
Cytosolic Glutamine Synthetase in Soybean Is Encoded by a Multigene Family, and the Members Are Regulated in an Organ-Specific and Developmental Manner
Plant Physiology, January 1, 2002; 128(1): 182 - 193.
[Abstract] [Full Text] [PDF]

Home page
 Plant Physiol.Home page
J. L. Ortega, S. J. Temple, and C. Sengupta-Gopalan
Constitutive Overexpression of Cytosolic Glutamine Synthetase (GS1) Gene in Transgenic Alfalfa Demonstrates That GS1 May Be Regulated at the Level of RNA Stability and Protein Turnover
Plant Physiology, May 1, 2001; 126(1): 109 - 121.
[Abstract] [Full Text]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ASPB Publications PLANT PHYSIOLOGY® THE PLANT CELL
Copyright © 1999 by the American Society of Plant Biologists