The FASEB Journal, Vol 2, 2591-2595, Copyright © 1988 by The Federation of American Societies for Experimental Biology

RESEARCH COMMUNICATIONS

Modulation of the hydrophobicity of glutamine synthetase by mixed- function oxidation

J Cervera and RL Levine
Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892.

Oxidative modification of Escherichia coli glutamine synthetase renders the enzyme susceptible to proteolytic degradation by a specific protease purified from the bacterium; native enzyme is not a substrate for the protease. A model oxidizing system consisting of ascorbate, iron, and oxygen was used to generate a series of glutamine synthetases of increasing oxidative modification. We assessed the effect of oxidative modification on the surface hydrophobicity of the glutamine synthetases, utilizing hydrophobic chromatography on a phenyl matrix. Initial exposure to the oxidizing system caused inactivation of the enzyme and generated a protein that was more hydrophilic than the native form; it was not a substrate for the protease. Continued exposure to the oxidizing system yielded a protein with additional oxidative modification. This form was distinctly more hydrophobic than the native form and it was very susceptible to proteolytic attack by the purified protease. Thus, oxidative modification modulates the surface hydrophobicity of glutamine synthetase, and this modulation can control susceptibility to proteolysis.

This article has been cited by other articles:

				K. J.A. Davies and R. Shringarpure Preferential degradation of oxidized proteins by the 20S proteasome may be inhibited in aging and in inflammatory neuromuscular diseases Neurology, January 24, 2006; 66(1_suppl_1): S93 - S96. [Abstract] [Full Text] [PDF]

				L. Di Noto, L. J. Whitson, X. Cao, P. J. Hart, and R. L. Levine Proteasomal Degradation of Mutant Superoxide Dismutases Linked to Amyotrophic Lateral Sclerosis J. Biol. Chem., December 2, 2005; 280(48): 39907 - 39913. [Abstract] [Full Text] [PDF]

				T. GRUNE, T. REINHECKEL, J. A. NORTH, R. LI, P. B. BESCOS, R. SHRINGARPURE, and K. J. A. DAVIES Ezrin turnover and cell shape changes catalyzed by proteasome in oxidatively stressed cells FASEB J, October 1, 2002; 16(12): 1602 - 1610. [Abstract] [Full Text] [PDF]

				T. Grune, R. Shringarpure, N. Sitte, and K. Davies Age-Related Changes in Protein Oxidation and Proteolysis in Mammalian Cells J. Gerontol. A Biol. Sci. Med. Sci., November 1, 2001; 56(11): B459 - 467. [Abstract] [Full Text] [PDF]

				J. L. Ortega, D. Roche, and C. Sengupta-Gopalan Oxidative Turnover of Soybean Root Glutamine Synthetase. In Vitro and in Vivo Studies Plant Physiology, April 1, 1999; 119(4): 1483 - 1496. [Abstract] [Full Text]

				C.-C. Chao, Y.-S. Ma, and E. R. Stadtman Modification of protein surface hydrophobicity and methionine oxidation by oxidative systems PNAS, April 1, 1997; 94(7): 2969 - 2974. [Abstract] [Full Text] [PDF]

				R. L. Levine, L. Mosoni, B. S. Berlett, and E. R. Stadtman Methionine residues as endogenous antioxidants in proteins PNAS, December 24, 1996; 93(26): 15036 - 15040. [Abstract] [Full Text] [PDF]

				T. Grune, T. Reinheckel, and K. J.A. Davies Degradation of Oxidized Proteins in K562 Human Hematopoietic Cells by Proteasome J. Biol. Chem., June 28, 1996; 271(26): 15504 - 15509. [Abstract] [Full Text] [PDF]

				T. Grune, T. Reinheckel, M. Joshi, and K. J. A. Davies Proteolysis in Cultured Liver Epithelial Cells during Oxidative Stress J. Biol. Chem., February 3, 1995; 270(5): 2344 - 2351. [Abstract] [Full Text] [PDF]

				K. M. Daumer, A. U. Khan, and M. J. Steinbeck Chlorination of Pyridinium Compounds. POSSIBLE ROLE OF HYPOCHLORITE, N-CHLORAMINES, AND CHLORINE IN THE OXIDATION OF PYRIDINOLINE CROSS-LINKS OF ARTICULAR CARTILAGE COLLAGEN TYPE II DURING ACUTE INFLAMMATION J. Biol. Chem., October 27, 2000; 275(44): 34681 - 34692. [Abstract] [Full Text] [PDF]