Oxidized amino acid residues in the vicinity of Q(A) and Pheo(D1) of the photosystem II reaction center: putative generation sites of reducing-side reactive oxygen species

• Published in: PloS one Vol. 8; no. 2; p. e58042
• Main Authors: Frankel, Laurie K, Sallans, Larry, Limbach, Patrick A, Bricker, Terry M
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science (PLoS) 2013
• Subjects: Amino Acid Sequence; Amino Acids; Catalytic Domain; Mass Spectrometry; Models, Molecular; Molecular Sequence Data; Oxidation-Reduction; Photosystem II Protein Complex - chemistry; Photosystem II Protein Complex - metabolism; Reactive Oxygen Species - metabolism; Spinacia oleracea - enzymology; Spinacia oleracea - growth & development; Spinacia oleracea - metabolism
• ISSN: 1932-6203
• DOI: 10.1371/journal.pone.0058042

Under a variety of stress conditions, Photosystem II produces reactive oxygen species on both the reducing and oxidizing sides of the photosystem. A number of different sites including the Mn4O5Ca cluster, P680, PheoD1, QA, QB and cytochrome b559 have been hypothesized to produce reactive oxygen species in the photosystem. In this communication using Fourier-transform ion cyclotron resonance mass spectrometry we have identified several residues on the D1 and D2 proteins from spinach which are oxidatively modified and in close proximity to QA (D1 residues (239)F, (241)Q, (242)E and the D2 residues (238)P, (239)T, (242)E and (247)M) and PheoD1 (D1 residues (130)E, (133)L and (135)F). These residues may be associated with reactive oxygen species exit pathways located on the reducing side of the photosystem, and their modification may indicate that both QA and PheoD1 are sources of reactive oxygen species on the reducing side of Photosystem II.