Glutathione peroxidase 3 of Saccharomyces cerevisiae suppresses non-enzymatic proteolysis of glutamine synthetase in an activity-independent manner.
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.
Lee
Phil Young
PY
Translational Research Center, KRIBB, Daejeon 305-806, South Korea.
Kho
Chang Won
CW
Lee
Do Hee
DH
Kang
Sunghyun
S
Kang
Seongman
S
Lee
Sang Chul
SC
Park
Byoung Chul
BC
Cho
Sayeon
S
Bae
Kwang-Hee
KH
Park
Sung Goo
SG
D002384:Catalysis / Q000187:drug effects; D020134:Catalytic Domain; D002712:Chlorides; D004492:Edetic Acid / Q000494:pharmacology; D015180:Electrophoresis, Gel, Two-Dimensional; D005290:Ferric Compounds / Q000494:pharmacology; D005974:Glutamate-Ammonia Ligase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015151:Immunoblotting; D011485:Protein Binding / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D002712:Chlorides; D005290:Ferric Compounds; D029701:Saccharomyces cerevisiae Proteins; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D005979:Glutathione Peroxidase; C494438:HYR1 protein, S cerevisiae; D005974:Glutamate-Ammonia Ligase; C024555:ferric chloride