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11 p.-2 fig.-3 tab. ; The cytoskeleton is a supramolecular structure consisting of interacting protein networks that support cell dynamics in essential processes such as migration and division, as well as in responses to stress. Fast cytoskeletal remodeling is achieved with the participation of regulatory proteins and posttranslational modifications (PTMs).Redox-related PTMs are emerging as critical players in cytoskeletal regulation. Here we used a cellular model of mild nitroxidative stress in which a peroxynitrite donor induced transient changes in the organization of three key cytoskeletal proteins, i.e., vimentin, actin and tubulin. Nitroxidative stress-induced reconfiguration of intermediate filaments, microtubules and actin structures were further correlated with their PTM profiles and dynamics of the PTM landscape. Using high-resolution mass spectrometry, 62 different PTMs were identified and relatively quantified in vimentin, actin and tubulin, including 12 enzymatic, 13 oxidative and 2 nitric oxidederived modifications as well as 35 modifications by carbonylated lipid peroxidation products, thus evidencing the occurrence of a chain reaction with formation of numerous reactive species and activation of multiple signaling pathways. Our results unveil the presence of certain modifications under basal conditions and their modulation in response to stress in a target-, residue- and reactive species-dependent manner. Thus, some modifications accumulated during the experiment whereas others varied transiently. Moreover, we identified protein PTM "hot spots", such as the single cysteine residue of vimentin, which was detected in seven modified forms, thus, supporting its role in PTM crosstalk and redox sensing. Finally, identification of novel PTMs in these proteins paves the way for unveiling new cytoskeleton regulatory mechanisms. ; This work was funded by Deutsche Forschungsgemeinschaft (DFG;FE-1236/31 to M.F.), European Regional Development Fund (ERDF,European Union and Free State Saxony; 100146238 and 100121468 to MF), and MASSTRPLAN project funded by the Marie Sklodowska-Curie EU Framework for Research and Innovation Horizon 2020 (Grant Agreement No. 675132, to MF and DPS). EG STSM at CIB-CSIC was supported by COST Action CM1001. DPS work has been supported by Agencia Estatal de Investigación, MINECO/ERDF (grants SAF2015-68590R and RTI2018-097624-B-I00), and ISCIII/ERDF (RETIC ARADYAL RD16/0006/0021). ; Peer reviewed

15 pages, 9 figures, 2 tables ; Cytochrome c (cyt c) is a small hemoprotein involved in electron shuttling in the mitochondrial respiratory chain and is now also recognized as an important mediator of apoptotic cell death. Its role in inducing programmed cell death is closely associated with the formation of a complex with the mitochondrion-specific phospholipid cardiolipin (CL), leading to a gain of peroxidase activity. However, the molecular mechanisms behind this gain and eventual cyt c autoinactivation via its release from mitochondrial membranes remain largely unknown. Here, we examined the kinetics of the H2O2-mediated peroxidase activity of cyt c both in the presence and absence of tetraoleoyl cardiolipin (TOCL)- and tetralinoleoyl cardiolipin (TLCL)-containing liposomes to evaluate the role of cyt c–CL complex formation in the induction and stimulation of cyt c peroxidase activity. Moreover, we examined peroxide-mediated cyt c heme degradation to gain insights into the mechanisms by which cyt c self-limits its peroxidase activity. Bottom-up proteomics revealed >50 oxidative modifications on cyt c upon peroxide reduction. Of note, one of these by-products was the Tyr-based "cofactor" trihydroxyphenylalanine quinone (TPQ) capable of inducing deamination of Lys ϵ-amino groups and formation of the carbonylated product aminoadipic semialdehyde. In view of these results, we propose that autoinduced carbonylation, and thus removal of a positive charge in Lys, abrogates binding of cyt c to negatively charged CL. The proposed mechanism may be responsible for release of cyt c from mitochondrial membranes and ensuing inactivation of its peroxidase activity ; This work was supported by the German Federal Ministry of Education and Research (BMBF) within the framework of the e:Med research and funding concept for the SysMedOS project, Deutsche Forschungsgemeinschaft (DFG) Grant FE-1236/3-1 (to M. F.), European Regional Development Fund (ERDF; European Union and Free State Saxony) Grants 100146238 and 100121468 (to M. F.), and a Xunta de Galicia postdoctoral scholarship (to L. M.) ; Peer reviewed

11 pages, 7 figures, 1 table.-- This is an open access article under the CC BY-NC-ND license ; Lipids are susceptible to damage by reactive oxygen species, and from lipid oxidation reactions many short chain lipid peroxidation products can be formed. 4-Hydroxy-2-nonenal (HNE) is one of the most abundant and cytotoxic lipid oxidation products and is known to form covalent adducts with nucleophilic amino acids of proteins. HNE-modified proteins have value as biomarkers and can be detected by antibody-based techniques, but most commercially available antibodies were raised against HNE-keyhole limpet hemocyanin. We used HNE-treated human serum albumin (HSA) to raise sheep antiserum and report for the first time the use of covalently modified peptide arrays to assess epitope binding of antibodies (Abs). Peptide arrays covering the sequence of HSA and treated post peptide synthesis with HNE were used to compare the different binding patterns of a commercial polyclonal antibody (pAb) raised against HNEtreated KLH and an in-house anti-HNE enriched pAb. The results were correlated with analysis of HNE-modified HSA by high-resolution tandem mass spectrometry. Both anti-HNE pAbs were found to bind strongly to eight common peptides on the HNE-treated HSA membranes, suggesting that HNE adducts per se induced an immune response in both cases even though different immunogens were used. Both antibodies bound with the highest affinity to the peptide 365DPHECYAKVFDEFKPLV381, which contains K378 and was also shown to be modified by the mass spectrometry analysis. Overall, the commercial anti-HNE pAb showed better specificity, recognizing nine out of the eleven adducts found by MS/MS, while the in-house enriched pAb only recognizes six. Nevertheless, the in-house pAb recognized specific peptides that were not recognized by the commercial pAb, which suggests the presence of clones uniquely specific to HNE adducts on HSA ; This research has received funding from the European Union's Horizon 2020 research and innovation programme under the MASSTRPLAN Marie Sklowdowska-Curie grant agreement number 67513. The financial support from German Federal Ministry of Education and Research (BMBF) within the framework of the e:Med research and funding concept for SysMedOS project (to MF) is gratefully acknowledged. Xunta de Galicia is acknowledged with thanks for the postdoctoral scholarship provided to L.M. ; Peer reviewed

19 Pags.- 2 Tabls.- 11 Figs.- Supp. Data (15 Figs.- 5 Tabls.- 4 DataSets). Copyright © 2018 American Society of Plant Biologists. All rights reserved. Authors cannot archive post-print (ie final draft post-refereeing): Must link to publisher version, toll-free link provided. ; Nitrogen fixation is an agronomically and environmentally important process catalyzed by bacterial nitrogenase within legume root nodules. These unique symbiotic organs have high metabolic rates and produce large amounts of reactive oxygen species that may modify proteins irreversibly. Here, we examined two types of oxidative posttranslational modifications of nodule proteins: carbonylation, which occurs by direct oxidation of certain amino acids or by interaction with reactive aldehydes arising from cell membrane lipid peroxides; and glycation, which results from the reaction of lysine and arginine residues with reducing sugars or their autooxidation products. We used a strategy based on the enrichment of carbonylated peptides by affinity chromatography followed by liquid chromatography-tandem mass spectrometry to identify 369 oxidized proteins in bean (Phaseolus vulgaris) nodules. Of these, 238 corresponded to plant proteins and 131 to bacterial proteins. Lipid peroxidation products induced most carbonylation sites. This study also revealed that carbonylation has major effects on two key nodule proteins. Metal-catalyzed oxidation caused the inactivation of malate dehydrogenase and the aggregation of leghemoglobin. In addition, numerous glycated proteins were identified in vivo, including three key nodule proteins: sucrose synthase, glutamine synthetase, and glutamate synthase. Label-free quantification identified 10 plant proteins and 18 bacterial proteins as age-specifically glycated. Overall, our results suggest that the selective carbonylation or glycation of crucial proteins involved in nitrogen metabolism, transcriptional regulation, and signaling may constitute a mechanism to control cell metabolism and nodule senescence. ; This work was supported by the Ministerio de Economía y Competitividad-Fondos Europeos de Desarrollo Regional (grant AGL2014-53717-R to M.A.M. and M.B.), by the German Research Society (grant FR3117/2-1 to A.F. and A.K.), by the Russian Foundation for Basic Research (grant 18-016-00190 to A.F.), by the Deutsche Forschungsgemeinschaft (grant FE-1236/3-1 to M.F.), and by the European Regional Development Fund (European Union and Free State Saxony; grants 100146238 and 100121468 to M.F.). ; Peer reviewed