title: Oxidation, inactivation and aggregation of protein disulfide isomerase promoted by the bicarbonate-dependent peroxidase activity of human superoxide dismutase.
abstract: Protein disulfide isomerase (PDI) is a dithiol-disulfide oxidoreductase that has essential roles in redox protein folding. PDI has been associated with protective roles against protein aggregation, a hallmark of neurodegenerative diseases. Intriguingly, PDI has been detected in the protein inclusions found in the central nervous system of patients of neurodegenerative diseases. Oxidized proteins are also consistently detected in such patients, but the agents that promote these oxidations remain undefined. A potential trigger of protein oxidation is the bicarbonate-dependent peroxidase activity of the human enzyme superoxide dismutase 1 (hSOD1). Therefore, we examined the effects of this activity on PDI structure and activity. The results showed that PDI was oxidized to radicals that lead to PDI inactivation and aggregation. The aggregates are huge and apparently produced by covalent cross-links. Spin trapping experiments coupled with MS analysis indicated that at least 3 residues of PDI are oxidized to tyrosyl radicals (Y(63), Y(116) and Y(327)). Parallel experiments showed that PDI is also oxidized to radicals, inactivated and aggregated by the action of photolytically generated carbonate radical and by UV light. PDI is prone to inactivation and aggregation by one-electron oxidants and UV light probably because of its high content of aromatic amino acids.
authors: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Caixa Postal 26077, São Paulo CEP 05513-970, Brazil.
authors: Asif
authors: A
authors: Iqbal
authors: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Caixa Postal 26077, São Paulo CEP 05513-970, Brazil.
authors: Veronica
authors: V
authors: Paviani
authors: Vascular Biology Laboratory, Heart Institute (InCor), School of Medicine, University of São Paulo, São Paulo CEP 05403-000, Brazil.
authors: Ana Iochabel
authors: AI
authors: Moretti
authors: Vascular Biology Laboratory, Heart Institute (InCor), School of Medicine, University of São Paulo, São Paulo CEP 05403-000, Brazil.
authors: Francisco R M
authors: FR
authors: Laurindo
authors: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Caixa Postal 26077, São Paulo CEP 05513-970, Brazil. Electronic address: oaugusto@iq.usp.br.
authors: Ohara
authors: O
authors: Augusto
mesh_terms: D001639:Bicarbonates / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D010084:Oxidation-Reduction; D019704:Protein Disulfide-Isomerases / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D001639:Bicarbonates; D013482:Superoxide Dismutase; D019704:Protein Disulfide-Isomerases
keywords: Carbonate radical; Dityrosine; Neurodegenerative diseases; Protein aggregation; Protein disulfide isomerase; Protein oxidation; Protein radicals; Superoxide dismutase 1; UV light