May Cytochrome b-559 function to protect photosystem II from ligh stress?

细胞色素 b-559 可以发挥保护光系统 II 免受轻应激的作用吗？

• 批准号: 06640845
• 负责人: OKAYAMA Shigeki
• 金额: $ 0.26万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06640845/
• 关键词: Photosystem II; cytochrome b-559; light stress; photoinhibition; redox potentials; Mnクラスター; 光障害; 光傷害; シトクロムb559

Effects of photoinhibition on the redox properties of cytochrome b-559 were studied with NH_2OH-treated photosystem II membranes, which are depleted of the water-oxidizing complex. The membranes contained three redox forms (HP-, IP-and LP-forms) of cytochrome b-559, with Em valuse of +435, +237 and +45mV,respectively. A novel intermediate-potential form of cytochrome b-559 was generated during photoinhibition on the donor side of photosystem II : photoinhibitory illumination (7,000 muEm-^2s^1) for 1 min induced a 28% decrease in the level of the HP-form, with concomitant generation of an intermediate-potential (IP'-) form whose Em value was about+350mV.Prolonged illumination (10min) resulted in complete loss of the HP-form and an apparent increase in the level of the IP-form. After further photoinhibitory treatment (60min), complete loss of the IP'-form was observed and levels of the IP- and LP-forms each increased to about 50% of the total amount of cytochromeb-559. Kinetic analysis of these data led to the conclusion that the HP-form is converted to the LP-form via two intermediate-potential forms (IP' and IP), and that IP'-form appears only at the early phase of photoinhibition.Kinetical analysis of the decays of the HP- and IP'-forms shows that the conversion of the HP- to the IP'-form occures in parallel with the photoinactivation of Tyr_Z, and that the disapperance of the IP'-form reflects the fate of Tyr_D. On these findings, we propose that the HP- and IP'-forms of cyotochrome b-559 donate electrons to Tyr_Z, respectively, to suppress their overoxidation, and so prevent the photoinhibition of the phtosystem II.

用 NH_2OH 处理的光系统 II 膜（耗尽了水氧化复合物）研究了光抑制对细胞色素 b-559 氧化还原特性的影响。该膜含有细胞色素b-559的三种氧化还原形式（HP-、IP-和LP-形式），Em值分别为+435、+237和+45mV。在光系统 II 供体侧的光抑制过程中，产生了一种新的中间电位形式的细胞色素 b-559：光抑制照明 (7,000 muEm-^2s^1) 1 分钟诱导 HP 形式的水平下降 28%，同时生成中间电位 (IP'-) 形式，其 Em 值约为 +350mV。延长照明 （10 分钟）导致 HP 形式完全丧失，IP 形式水平明显增加。进一步光抑制处理（60分钟）后，观察到IP'-形式完全丧失，并且IP-和LP-形式的水平各自增加至细胞色素b-559总量的约50%。对这些数据的动力学分析得出结论，HP-形式通过两种中间电位形式（IP'和IP）转化为LP-形式，并且IP'-形式仅出现在光抑制的早期阶段。HP-和IP'-形式的衰变动力学分析表明，HP-形式向IP'-形式的转化与Tyr_Z的光失活同时发生，并且消失 IP'-形式的变化反映了 Tyr_D 的命运。根据这些发现，我们提出细胞色素 b-559 的 HP-和 IP'-形式分别向 Tyr_Z 提供电子，以抑制其过度氧化，从而防止光系统 II 的光抑制。

项目成果

田村典明: "Evidence on the specific interaction between manganese and cyt b-559 on ths PS II oxidizing side" Photosynthesis : from Light to Biosphere (P.Mathis ed.) Kluwer Academic Publisheers,The Netherlands.

Noriaki Tamura：“关于锰和 cyt b-559 在 PS II 氧化侧上的特定相互作用的证据”光合作用：从光到生物圈（P.Mathis 编辑）Kluwer 学术出版社，荷兰。

Iwasaki, I.: "Effects of light stress on redox potential froms of Cytb-559 in Photosystem II membranes depleted of water-oxidizing complex." Plant and Cell Physiology. 36. 583-589 (1995)

Iwasaki, I.：“光应激对水氧化复合物耗尽的光系统 II 膜中 Cytb-559 氧化还原电位的影响。”

Iwasaki,I.: "Effects of ligh stress on redox potential forms of Cytb-559 in Photosystem II membranes depleted of water oxidizing complex" Plant and Cell Physiology. 36(印刷中). (1995)

Iwasaki, I.：“光系统 II 膜中缺水氧化复合物中 Cytb-559 氧化还原电位形式的影响”植物和细胞生理学 36（出版中）。

岩崎郁子: "Effects of light stress on redox potential forms of cyt b-559 in photosytem II membranes depleted of water oxidizing complex" Plant and Cell Physiology.

Ikuko Iwasaki：“光胁迫对水氧化复合物耗尽的光系统 II 膜中细胞色素 b-559 氧化还原电位形式的影响”植物和细胞生理学。

Tamura, N.: "Evidence on the specific interaction between mangancese and cyt b-559 on the PSII oxidizing side" Photosynthesis : from Light to Biosphere (P.Mathis ed.), Kluwer Academic Publisheers, The Netherlands. Vol.II. 337-340 (1995)

Tamura, N.：“PSII 氧化侧锰与细胞色素 b-559 之间特异性相互作用的证据”光合作用：从光到生物圈（P.Mathis 编辑），Kluwer 学术出版社，荷兰。