TY - JOUR
T1 - Modulation of lysozyme function and degradation after nitration with peroxynitrite
AU - Curry-McCoy, Tiana V.
AU - Osna, Natalia A.
AU - Donohue, Terrence M.
N1 - Funding Information:
The authors are pleased to acknowledge support provided by fellowship number 1 F31 AA017045-01 (to TCM) and by grant number AA09384 (to TMD) from the National Institute of Alcohol Abuse and Alcoholism.
PY - 2009/8
Y1 - 2009/8
N2 - Background: Peroxynitrite (PN) is formed from superoxide and nitric oxide, both of which are increased during hepatic ethanol metabolism. Peroxynitrite forms adducts with proteins, causing structural and functional alterations. Here, we investigated PN-induced alterations in lysozyme structure and function, and whether they altered the protein's susceptibility to proteasome-catalyzed degradation. Methods: Hen egg lysozyme was nitrated using varying amounts of either PN or the PN donor, 3-morpholinosydnonimine (SIN-1). The activity, nitration status and the susceptibility of lysozyme to proteasome-catalyzed degradation were assessed. Results: Lysozyme nitration by PN or SIN-1 caused dose-dependent formation of 3-nitrotyrosine-lysozyme adducts, causing decreased catalytic activity, and enhanced susceptibility to degradation by the 20S proteasome. Kinetic analyses revealed an increased affinity by the 20S proteasome toward nitrated lysozyme compared with the native protein. Conclusion: Lysozyme nitration enhances the affinity of the modified enzyme for degradation by the proteasome, thereby increasing its susceptibility to proteolysis. General significance: Increased levels of peroxynitrite have been detected in tissues of ethanol-fed animals. The damaging effects from excessive peroxynitrite in the cell increase hepatotoxicity and cellular death by protein modification due to nitration. Cellular defenses against such changes include enhanced proteolysis by the proteasome in order to maintain protein quality control.
AB - Background: Peroxynitrite (PN) is formed from superoxide and nitric oxide, both of which are increased during hepatic ethanol metabolism. Peroxynitrite forms adducts with proteins, causing structural and functional alterations. Here, we investigated PN-induced alterations in lysozyme structure and function, and whether they altered the protein's susceptibility to proteasome-catalyzed degradation. Methods: Hen egg lysozyme was nitrated using varying amounts of either PN or the PN donor, 3-morpholinosydnonimine (SIN-1). The activity, nitration status and the susceptibility of lysozyme to proteasome-catalyzed degradation were assessed. Results: Lysozyme nitration by PN or SIN-1 caused dose-dependent formation of 3-nitrotyrosine-lysozyme adducts, causing decreased catalytic activity, and enhanced susceptibility to degradation by the 20S proteasome. Kinetic analyses revealed an increased affinity by the 20S proteasome toward nitrated lysozyme compared with the native protein. Conclusion: Lysozyme nitration enhances the affinity of the modified enzyme for degradation by the proteasome, thereby increasing its susceptibility to proteolysis. General significance: Increased levels of peroxynitrite have been detected in tissues of ethanol-fed animals. The damaging effects from excessive peroxynitrite in the cell increase hepatotoxicity and cellular death by protein modification due to nitration. Cellular defenses against such changes include enhanced proteolysis by the proteasome in order to maintain protein quality control.
KW - 20S proteasome
KW - Ethanol
KW - Kinetics
KW - Lysozyme
KW - Oxidative stress
KW - Peroxynitrite
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U2 - 10.1016/j.bbagen.2009.04.008
DO - 10.1016/j.bbagen.2009.04.008
M3 - Article
C2 - 19376194
AN - SCOPUS:67649321463
SN - 0304-4165
VL - 1790
SP - 778
EP - 786
JO - Biochimica et Biophysica Acta - General Subjects
JF - Biochimica et Biophysica Acta - General Subjects
IS - 8
ER -