Redox-sensitivity and site-specificity of S- and N- denitrosation in proteins
Bauer, Joseph Alan, Jourd'heuil, Frances L., Lowery, Anthony M., Melton, Elaina M., Mnaimneh, Sanie, Bryan, Nathan S., Fernandez, Bernadette O., Park, Joo-Ho, Ha, Chung-Eun, Bhagavan, Nadhipuram V., Feelisch, Martin and Jourd'heuil, David. (2010) Redox-sensitivity and site-specificity of S- and N- denitrosation in proteins. PLoS One, Vol.5 (No.12). e14400. ISSN 1932-6203Full text not available from this repository.
Official URL: http://dx.doi.org/10.1371/journal.pone.0014400
S-nitrosation – the formation of S-nitrosothiols (RSNOs) at cysteine residues in proteins – is a posttranslational modification involved in signal transduction and nitric oxide (NO) transport. Recent studies would also suggest the formation of N-nitrosamines (RNNOs) in proteins in vivo, although their biological significance remains obscure. In this study, we characterized a redox-based mechanism by which N-nitroso-tryptophan residues in proteins may be denitrosated.
The denitrosation of N-acetyl-nitroso Trp (NANT) by glutathione (GSH) required molecular oxygen and was inhibited by superoxide dismutase (SOD). Transnitrosation to form S-nitrosoglutathione (GSNO) was observed only in the absence of oxygen or presence of SOD. Protein denitrosation by GSH was studied using a set of mutant recombinant human serum albumin (HSA). Trp-214 and Cys-37 were the only two residues nitrosated by NO under aerobic conditions. Nitroso-Trp-214 in HSA was insensitive to denitrosation by GSH or ascorbate while denitrosation at Cys-37 was evident in the presence of GSH but not ascorbate. GSH-dependent denitrosation of Trp-214 was restored in a peptide fragment of helix II containing Trp-214. Finally, incubation of cell lysates with NANT revealed a pattern of protein nitrosation distinct from that observed with GSNO.
We propose that the denitrosation of nitrosated Trp by GSH occurs through homolytic cleavage of nitroso Trp to NO and a Trp aminyl radical, driven by the formation of superoxide derived from the oxidation of GSH to GSSG. Overall, the accessibility of Trp residues to redox-active biomolecules determines the stability of protein-associated nitroso species such that in the case of HSA, N-nitroso-Trp-214 is insensitive to denitrosation by low-molecular-weight antioxidants. Moreover, RNNOs can generate free NO and transfer their NO moiety in an oxygen-dependent fashion, albeit site-specificities appear to differ markedly from that of RSNOs.
|Item Type:||Journal Article|
|Subjects:||R Medicine > R Medicine (General)|
|Divisions:||Faculty of Medicine > Warwick Medical School > Translational & Systems Medicine > Metabolic and Vascular Health
Faculty of Medicine > Warwick Medical School
|Journal or Publication Title:||PLoS One|
|Publisher:||Public Library of Science|
|Official Date:||21 December 2010|
|Access rights to Published version:||Open Access|
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