title: S-nitrosylation of ascorbate peroxidase is part of programmed cell death signaling in tobacco Bright Yellow-2 cells.
abstract: Nitric oxide (NO) is a small redox molecule that acts as a signal in different physiological and stress-related processes in plants. Recent evidence suggests that the biological activity of NO is also mediated by S-nitrosylation, a well-known redox-based posttranslational protein modification. Here, we show that during programmed cell death (PCD), induced by both heat shock (HS) or hydrogen peroxide (H2O2) in tobacco (Nicotiana tabacum) Bright Yellow-2 cells, an increase in S-nitrosylating agents occurred. NO increased in both experimentally induced PCDs, although with different intensities. In H2O2-treated cells, the increase in NO was lower than in cells exposed to HS. However, a simultaneous increase in S-nitrosoglutathione (GSNO), another NO source for S-nitrosylation, occurred in H2O2-treated cells, while a decrease in this metabolite was evident after HS. Consistently, different levels of activity and expression of GSNO reductase, the enzyme responsible for GSNO removal, were found in cells subjected to the two different PCD-inducing stimuli: low in H2O2-treated cells and high in the heat-shocked ones. Irrespective of the type of S-nitrosylating agent, S-nitrosylated proteins formed upon exposure to both of the PCD-inducing stimuli. Interestingly, cytosolic ascorbate peroxidase (cAPX), a key enzyme controlling H2O2 levels in plants, was found to be S-nitrosylated at the onset of both PCDs. In vivo and in vitro experiments showed that S-nitrosylation of cAPX was responsible for the rapid decrease in its activity. The possibility that S-nitrosylation induces cAPX ubiquitination and degradation and acts as part of the signaling pathway leading to PCD is discussed.
authors.affiliation: Dipartimento Biologia, Università degli Studi di Bari, 70125 Bari, Italy.
authors.forename: Maria Concetta
authors.initials: MC
authors.lastname: de Pinto
authors.forename: Vittoria
authors.initials: V
authors.lastname: Locato
authors.forename: Alessandra
authors.initials: A
authors.lastname: Sgobba
authors.forename: Maria Del Carmen
authors.initials: Mdel C
authors.lastname: Romero-Puertas
authors.forename: Cosimo
authors.initials: C
authors.lastname: Gadaleta
authors.forename: Massimo
authors.initials: M
authors.lastname: Delledonne
authors.forename: Laura
authors.initials: L
authors.lastname: De Gara
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D060387:Ascorbate Peroxidases / Q000302:isolation & purification / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006862:Hydrogen Sulfide / Q000494:pharmacology; D007700:Kinetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000378:metabolism; D015538:Nitrosation / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D026422:S-Nitrosoglutathione / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014026:Nicotiana / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D025801:Ubiquitin / Q000378:metabolism; D054875:Ubiquitination / Q000187:drug effects
chemical_list: D025801:Ubiquitin; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D006861:Hydrogen Peroxide; D060387:Ascorbate Peroxidases; D000445:Aldehyde Oxidoreductases; C087006:formaldehyde dehydrogenase, glutathione-independent; D006862:Hydrogen Sulfide