Glutathione peroxidase 3 of Saccharomyces cerevisiae suppresses non-enzymatic proteolysis of glutamine synthetase in an activity-independent manner

• Published in: Biochemical and biophysical research communications Vol. 362; no. 2; pp. 405 - 409
• Main Authors: Lee, Phil Young, Kho, Chang Won, Lee, Do Hee, Kang, Sunghyun, Kang, Seongman, Lee, Sang Chul, Park, Byoung Chul, Cho, Sayeon, Bae, Kwang-Hee, Park, Sung Goo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 19.10.2007
• Subjects: Catalysis - drug effects; Catalytic Domain; Chlorides; Edetic Acid - pharmacology; Electrophoresis, Gel, Two-Dimensional; Ferric Compounds - pharmacology; Glutamate-Ammonia Ligase - chemistry; Glutamate-Ammonia Ligase - genetics; Glutamate-Ammonia Ligase - metabolism; Glutamine synthetase; Glutathione Peroxidase - chemistry; Glutathione Peroxidase - genetics; Glutathione Peroxidase - metabolism; Glutathione peroxidase 3; Hydrogen Peroxide - pharmacology; Immunoblotting; MFO system; Oxidative stress; Protein Binding - drug effects; ROS; Saccharomyces cerevisiae; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Glutathione peroxidase 3; Oxidative stress; Gpx3; MFO; Prx; ROS; MFO system; Glutamine synthetase; GS
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2007.08.035

Glutathione peroxidase 3 (Gpx3) is ubiquitously expressed and is important antioxidant enzyme in yeast. It modulates the activities of redox-sensitive thiol proteins, particularly those involved in signal transduction pathway and protein translocation. Through immunoprecipitation/two-dimensional gel electrophoresis (IP-2DE), MALDI-TOF mass spectrometry, and a pull down assay, we found glutamine synthetase (GS; EC 6.3.1.2) as a candidate interacting protein with Gpx3. GS is a key enzyme in nitrogen metabolism and ammonium assimilation. It has been known that GS is non-enzymatically cleaved by ROS generated by MFO (thiol/ Fe 3+/O 2 mixed-function oxidase) system. In this study, it is demonstrated that GS interacts with Gpx3 through its catalytic domain both in vivo and in vitro regardless of redox state. In addition, Gpx3 helps to protect GS from inactivation and degradation via oxidative stress in an activity-independent manner. Based on the results, it is suggested that Gpx3 protects GS from non-enzymatic proteolysis, thereby contributing to cell homeostasis when cell is exposed to oxidative stress.