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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.

Frankel LK, Sallans L, Limbach PA, Bricker TM - PLoS ONE (2013)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Division of Biochemistry and Molecular Biology, Louisiana State University, Baton Rouge, Louisiana, United States of America.

ABSTRACT
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.

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Detail of the Oxidized Residues in the Vicinity of PheoD1.The T. vulcanus residues corresponding to the oxidatively modified spinach residues (Table 1) are highlighted and labeled. The D1 protein is shown in pale green and the D2 protein is shown in pale yellow. The oxidatively modified residues of D1 are shown in dark green, with the individual modified residues being labeled. PheoD1 is shown in bright green, QA is shown in yellow, QB in green and the non-heme iron is shown in bright red. For clarity, modified residues in the vicinity of QA (and detailed in Fig. 3) are not shown.
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pone-0058042-g004: Detail of the Oxidized Residues in the Vicinity of PheoD1.The T. vulcanus residues corresponding to the oxidatively modified spinach residues (Table 1) are highlighted and labeled. The D1 protein is shown in pale green and the D2 protein is shown in pale yellow. The oxidatively modified residues of D1 are shown in dark green, with the individual modified residues being labeled. PheoD1 is shown in bright green, QA is shown in yellow, QB in green and the non-heme iron is shown in bright red. For clarity, modified residues in the vicinity of QA (and detailed in Fig. 3) are not shown.

Mentions: With respect to the residues in close proximity to PheoD1, D1:130E in spinach and Chlamydomnas is replaced by D1:130Q in the T. vucanus structure. It should be noted that in T. vulcanus, D1:130Q is present in the constitutively expressed D1–1 isoform while the D1–2 and D1–3 isoforms, which are expressed only under certain environmental conditions, contain D1:130E [31], [32]. These residues have been reported to be hydrogen- bonded to PheoD1[33], [34]. Additionally, in Thermosynechococcus, D1:135Y is replaced by D1:135F (Table 1). Consequently, in the Thermosynechococcus structure: PheoD1 – 2.9Å – D1:130Q – D1:133L –D1:135F (Fig. 4). The mass spectrum identifying this group of modified residues is shown in Fig. S3. These oxidized residues may be adjacent to a putative ROS exit pathway leading from PheoD1 to residues near or at the surface of the complex. It should be noted that in the static crystal structure, none of these residues are surface-exposed nor are they in contact with any apparent cavities or channels. Other residues which were not detected in our studies may be associated with the putative pathway, completing a pathway to the surface of the complex.


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.

Frankel LK, Sallans L, Limbach PA, Bricker TM - PLoS ONE (2013)

Detail of the Oxidized Residues in the Vicinity of PheoD1.The T. vulcanus residues corresponding to the oxidatively modified spinach residues (Table 1) are highlighted and labeled. The D1 protein is shown in pale green and the D2 protein is shown in pale yellow. The oxidatively modified residues of D1 are shown in dark green, with the individual modified residues being labeled. PheoD1 is shown in bright green, QA is shown in yellow, QB in green and the non-heme iron is shown in bright red. For clarity, modified residues in the vicinity of QA (and detailed in Fig. 3) are not shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585169&req=5

pone-0058042-g004: Detail of the Oxidized Residues in the Vicinity of PheoD1.The T. vulcanus residues corresponding to the oxidatively modified spinach residues (Table 1) are highlighted and labeled. The D1 protein is shown in pale green and the D2 protein is shown in pale yellow. The oxidatively modified residues of D1 are shown in dark green, with the individual modified residues being labeled. PheoD1 is shown in bright green, QA is shown in yellow, QB in green and the non-heme iron is shown in bright red. For clarity, modified residues in the vicinity of QA (and detailed in Fig. 3) are not shown.
Mentions: With respect to the residues in close proximity to PheoD1, D1:130E in spinach and Chlamydomnas is replaced by D1:130Q in the T. vucanus structure. It should be noted that in T. vulcanus, D1:130Q is present in the constitutively expressed D1–1 isoform while the D1–2 and D1–3 isoforms, which are expressed only under certain environmental conditions, contain D1:130E [31], [32]. These residues have been reported to be hydrogen- bonded to PheoD1[33], [34]. Additionally, in Thermosynechococcus, D1:135Y is replaced by D1:135F (Table 1). Consequently, in the Thermosynechococcus structure: PheoD1 – 2.9Å – D1:130Q – D1:133L –D1:135F (Fig. 4). The mass spectrum identifying this group of modified residues is shown in Fig. S3. These oxidized residues may be adjacent to a putative ROS exit pathway leading from PheoD1 to residues near or at the surface of the complex. It should be noted that in the static crystal structure, none of these residues are surface-exposed nor are they in contact with any apparent cavities or channels. Other residues which were not detected in our studies may be associated with the putative pathway, completing a pathway to the surface of the complex.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Division of Biochemistry and Molecular Biology, Louisiana State University, Baton Rouge, Louisiana, United States of America.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus