Effect of protein modification by malondialdehyde on the interaction between the oxygen-evolving complex 33 kDa protein and photosystem II core proteins
Effect of protein modification by malondialdehyde on the interaction between the oxygen-evolving complex 33 kDa protein and photosystem II core proteins
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DOI：
10.1007/s00425-010-1112-2
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发表时间：
2010-02
期刊：
影响因子：
4.3
通讯作者：
Y. Yamauchi;Y. Sugimoto
中科院分区：
文献类型：
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作者：
Y. Yamauchi;Y. Sugimoto
之前，我们观察到稳定光系统II（PSII）中Mn簇的放氧复合物33 kDa蛋白（OEC33）被过氧化多不饱和脂肪酸的终产物丙二醛（MDA）修饰，并且该修饰在热胁迫植物中增加（Yamauchi et al. 2008）。在这项研究中，我们研究了OEC33与MDA的修改是否会影响其结合PSII复合物，并导致失活的放氧复合物。纯化的OEC 33和PSII膜，已被删除的外源蛋白的放氧复合物（PSII OEE）的菠菜（菠菜）分别用MDA处理。当OEC 33和PSII β-OEE都被修饰时，结合减弱，但当仅OEC 33或PSII β-OEE被处理时，结合不受损害。在使用类囊体膜的实验中，当类囊体膜在40 ° C下用MDA处理而不是在25 ° C下处理时，观察到OEC 33从PSII释放和相应的放氧活性损失。在40 ° C光照下处理的菠菜叶片中，PSII光化学的最大效率（叶绿素荧光的Fv/Fm比）和放氧活性降低。同时，热胁迫叶片中MDA含量增加，OEC33和PSII核心蛋白包括47和43 kDa的叶绿素结合蛋白被MDA修饰。相比之下，这些变化在黑暗中40 ° C时程度较小。这些结果表明，MDA修饰的PSII蛋白导致释放的OEC33从PSII和它是促进在热和氧化条件。
Previously we observed that the oxygen-evolving complex 33 kDa protein (OEC33) which stabilizes the Mn cluster in photosystem II (PSII), was modified with malondialdehyde (MDA), an end-product of peroxidized polyunsaturated fatty acids, and the modification increased in heat-stressed plants (Yamauchi et al. 2008). In this study, we examined whether the modification of OEC33 with MDA affects its binding to the PSII complex and causes inactivation of the oxygen-evolving complex. Purified OEC33 and PSII membranes that had been removed of extrinsic proteins of the oxygen-evolving complex (PSII∆OEE) of spinach (Spinacia oleracea) were separately treated with MDA. The binding was diminished when both OEC33 and PSII∆OEE were modified, but when only OEC33 or PSII∆OEE was treated, the binding was not impaired. In the experiment using thylakoid membranes, release of OEC33 from PSII and corresponding loss of oxygen-evolving activity were observed when thylakoid membranes were treated with MDA at 40°C but not at 25°C. In spinach leaves treated at 40°C under light, maximal efficiency of PSII photochemistry (Fv/Fmratio of chlorophyll fluorescence) and oxygen-evolving activity decreased. Simultaneously, MDA contents in heat-stressed leaves increased, and OEC33 and PSII core proteins including 47 and 43 kDa chlorophyll-binding proteins were modified with MDA. In contrast, these changes were to a lesser extent at 40°C in the dark. These results suggest that MDA modification of PSII proteins causes release of OEC33 from PSII and it is promoted in heat and oxidative conditions.