An unusual role for the phytyl chains in the photoprotection of the chlorophylls bound to Water-Soluble Chlorophyll-binding Proteins.
An unusual role for the phytyl chains in the photoprotection of the chlorophylls bound to Water-Soluble Chlorophyll-binding Proteins.
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DOI：
10.1038/s41598-017-07874-6
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发表时间：
2017-08-08
影响因子：
4.6
通讯作者：
Carbonera D
中科院分区：
文献类型：
--
作者：
Agostini A;Palm DM;Schmitt FJ;Albertini M;Valentin MD;Paulsen H;Carbonera D
十字花科植物中的水溶性叶绿素蛋白(WSCP)是一种非光合作用蛋白，与4个叶绿素(Chl)分子结合后发生四聚体反应。结合的CHL是高度光稳定性的，尽管在含有Chl的光合蛋白中缺乏结合的胡萝卜素，作为单态氧和Chl三联体(3Chl)的猝灭剂。虽然WSCP的生理功能尚不清楚，但很可能与其生化稳定性和抗光降解能力有关。为了深入了解这种光稳定性的起源，我们研究了WSCP在光照下产生的3Chl的性质。我们发现，与激子激发的单重态不同，三重态定位在单个Chl分子上。此外，在WSCP中生成的3Chl的寿命与在其他含Chl的体系中观察到的寿命相当，并且在存在氧的情况下会缩短。与以前的观察结果不同，我们发现WSCP实际上光敏单重态氧，其光敏化效率与有机溶剂中的Chl相当。我们证明了观察到的光氧化抗性取决于植基基团的构象，在WSCP中，植基基团插入到Chl二聚体的环之间，阻碍了单线态氧进入颜料的可氧化位置。
Water-Soluble Chlorophyll Proteins (WSCPs) from Brassicaceae are non-photosynthetic proteins which tetramerize upon binding four chlorophyll (Chl) molecules. The bound Chls are highly photostable, despite the lack of bound carotenoids known, in Chl-containing photosynthetic proteins, to act as singlet oxygen and Chl triplet (3Chl) quenchers. Although the physiological function of WSCPs is still unclear, it is likely to be related to their biochemical stability and their resistance to photodegradation. To get insight into the origin of this photostability, the properties of the 3Chl generated in WSCPs upon illumination were investigated. We found that, unlike the excited singlet states, which are excitonic states, the triplet state is localized on a single Chl molecule. Moreover, the lifetime of the 3Chl generated in WSCPs is comparable to that observed in other Chl-containing systems and is reduced in presence of oxygen. In contrast to previous observations, we found that WSCP actually photosensitizes singlet oxygen with an efficiency comparable to that of Chl in organic solvent. We demonstrated that the observed resistance to photooxidation depends on the conformation of the phytyl moieties, which in WSCP are interposed between the rings of Chl dimers, hindering the access of singlet oxygen to the oxidizable sites of the pigments.
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影响因子：
7.1
作者：
DI MASCIO, P;MURPHY, ME;SIES, H
通讯作者：
SIES, H
影响因子：
4.3
作者：
Carbonera, Donatella;Agostini, Alessandro;Morosinotto, Tomas
通讯作者：
Morosinotto, Tomas
影响因子：
1.7
作者：
Di Valentin, Marilena;Ceola, Stefano;Carbonera, Donatella
通讯作者：
Carbonera, Donatella
影响因子：
4.3
作者：
Di Valentin, Marilena;Ceola, Stefano;Carbonera, Donatella
通讯作者：
Carbonera, Donatella
影响因子：
5.6
作者：
Boex-Fontvieille E;Rustgi S;von Wettstein D;Pollmann S;Reinbothe S;Reinbothe C
通讯作者：
Reinbothe C