title: Mass spectrometric characterization of photooxidative protein modifications in Arabidopsis thaliana thylakoid membranes.
abstract: Oxidative and nitrosative stress leaves footprints in the plant chloroplast in the form of oxidatively modified proteins. Using a mass spectrometric approach, we identified 126 tyrosine and 12 tryptophan nitration sites in 164 nitrated proteolytic peptides, mainly from photosystem I (PSI), photosystem II (PSII), cytochrome b(6) /f and ATP-synthase complexes and 140 oxidation products of tyrosine, tryptophan, proline, phenylalanine and histidine residues. While a high number of nitration sites were found in proteins from four photosynthetic complexes indicating that the nitration belongs to one of the prominent posttranslational protein modifications in photosynthetic apparatus, amino acid oxidation products were determined mostly in PSII and to a lower extent in PSI. Exposure of plants to light stress resulted in an increased level of tyrosine and tryptophan nitration and tryptophan oxidation in proteins of PSII reaction center and the oxygen-evolving complex, as compared to low light conditions. In contrast, the level of nitration and oxidation of these amino acid residues strongly decreased for all light-harvesting proteins of PSII under the same conditions. Based on these data, we propose that oxidative modifications of proteins by reactive oxygen and nitrogen species might represent an important regulatory mechanism of protein turnover under light stress conditions, especially for PSII and its antenna proteins.
authors.affiliation: Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russian Federation.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Galetskiy
authors.forename: Jens N
authors.initials: JN
authors.lastname: Lohscheider
authors.forename: Alexey S
authors.initials: AS
authors.lastname: Kononikhin
authors.forename: Igor A
authors.initials: IA
authors.lastname: Popov
authors.forename: Eugene N
authors.initials: EN
authors.lastname: Nikolaev
authors.forename: Iwona
authors.initials: I
authors.lastname: Adamska
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry* / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods*; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D020524:Thylakoids / Q000737:chemistry* / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism
chemical_list: D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D014443:Tyrosine; D014364:Tryptophan; D009584:Nitrogen