Fate of nitrated proteins: denitration or degradation?
Biogerontology and Geriatric Medicine
Final Report Abstract
In addition to their role in the pathophysiology of several diseases, nitrated proteins also play an important role in the aging process. Accumulation of nitrated proteins during the aging process has already been demonstrated in different tissues and is accepted as a biomarker for increased oxidative and nitrosative stress. While the process of the spontaneous protein nitration is widely understood, the fate of nitrated proteins is not known yet. Previous studies on the fate of nitrated proteins have shown that proteolytic degradation and denitration are mainly responsible. In our preliminary work, we have already shown that slightly nitrated and oxidized proteins are removed by proteolytic degradation, while highly modified proteins impaired proteolysis. However, recent studies showed that proteolysis is not solely responsible for the fate of selectively nitrated proteins and peptides. A decrease in protein nitration without loss of protein amount confirmed the assumption of a denitrating activity, which we were able to detect in cytosol after LPS stimulation. Inactivation of enzyme activity by nitration (e.g. glutamine synthetase) and its reactivation in combination with denitration demonstrated the relevance of controlled protein nitration. The combination of the expertise of our group and our collaboration partners allows us to proceed further with the characterization in a promising way. In the current project we were able to show (i) that oxidized and nitrated proteins are degraded by the proteasome; (ii) that nitrated only proteins are poor proteasomal substrates; (iii) that a nitration signal is lost in proteins despite inhibited proteolysis, leading to the conclusion that a denitrase activity exists, (iv) that glutamine synthase is a selective model substrate protein for denitrase activity, and (v) that the denitrase activity is selective for specific Tyr residues.
Publications
- Posttranslational protein modifications by reactive nitrogen and chlorine species and strategies for their prevention and elimination (Review). Free Radical Res. (2014) 48:1267-84
I. Sadowska-Bartosz, C. Ott, T. Grune, G. Bartosz
(See online at https://doi.org/10.3109/10715762.2014.953494) - Exploring the catalytic mechanism of human glutamine synthetase by computer simulations. Biochemistry. 2016 Oct 13
Issoglio FM, Campolo N, Zeida A, Grune T, Radi R, Estrin DA, Bartesaghi S
(See online at https://doi.org/10.1021/acs.biochem.6b00822) - Cross-talk between lipid and protein carbonylation in a dynamic cardiomyocyte model of mild nitroxidative stress. Redox Biol. (2017) 11:438-455
Griesser E, Vemula V, Raulien N, Wagner U, Reeg S, Grune T, Fedorova M
(See online at https://doi.org/10.1016/j.redox.2016.12.028)
