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PsbS contributes to photoprotection in Chlamydomonas reinhardtii independently of energy dissipation.
Biochimica et Biophysica Acta (BBA) - Bioenergetics ( IF 4.3 ) Pub Date : 2020-03-12 , DOI: 10.1016/j.bbabio.2020.148183
Petra Redekop 1 , Natalie Rothhausen 1 , Natascha Rothhausen 1 , Michael Melzer 2 , Laura Mosebach 3 , Emin Dülger 1 , Anastasiia Bovdilova 1 , Stefano Caffarri 4 , Michael Hippler 5 , Peter Jahns 1
Affiliation  

Photosynthetic organisms are frequently exposed to excess light conditions and hence to photo-oxidative stress. To counteract photo-oxidative damage, land plants and most algae make use of non- photochemical quenching (NPQ) of excess light energy, in particular the rapidly inducible and relaxing qE-mechanism. In vascular plants, the constitutively active PsbS protein is the key regulator of qE. In the green algae C. reinhardtii, however, qE activation is only possible after initial high-light (HL) acclimation for several hours and requires the synthesis of LHCSR proteins which act as qE regulators. The precise function of PsbS, which is transiently expressed during HL acclimation in C. reinhardtii, is still unclear. Here, we investigated the impact of different PsbS amounts on HL acclimation characteristics of C. reinhardtii cells. We demonstrate that lower PsbS amounts negatively affect HL acclimation at different levels, including NPQ capacity, electron transport characteristics, antenna organization and morphological changes, resulting in an overall increased HL sensitivity and lower vitality of cells. Contrarily, higher PsbS amounts do not result in a higher NPQ capacity, but nevertheless provide higher fitness and tolerance towards HL stress. Strikingly, constitutively expressed PsbS protein was found to be degraded during HL acclimation. We propose that PsbS is transiently required during HL acclimation for the reorganization of thylakoid membranes and/or antenna proteins along with the activation of NPQ and adjustment of electron transfer characteristics, and that degradation of PsbS is essential in the fully HL acclimated state.



中文翻译:

PsbS有助于莱茵衣藻的光保护,而与能量耗散无关。

光合生物经常暴露在过量的光照条件下,因此遭受光氧化应激。为了抵消光氧化损伤,陆地植物和大多数藻类利用了多余光能的非光化学猝灭(NPQ),特别是快速诱导和松弛的qE机制。在维管植物中,组成型活性PsbS蛋白是qE的关键调节因子。在绿藻C中莱茵衣藻,然而,qE时激活是初始高光(HL)驯化后只可能数小时,并且需要LHCSR蛋白充当qE时调节器的合成。PsbS的精确功能,在C的HL适应过程中瞬时表达。赖因哈蒂,目前尚不清楚。在这里,我们调查了不同的PsbS量对C的HL适应特性的影响。赖因哈蒂细胞。我们证明,较低的PsbS含量会对HL适应水平产生不同程度的负面影响,包括NPQ容量,电子传输特性,天线组织和形态变化,从而导致整体HL敏感性增加和细胞活力降低。相反,较高的PsbS含量不会导致较高的NPQ能力,但仍会提供较高的适应性和对HL压力的耐受性。令人惊讶地,发现组成型表达的PsbS蛋白在HL适应过程中被降解。我们建议在HL适应过程中暂时需要PsbS来重组类囊体膜和/或触角蛋白,以及NPQ的激活和电子传递特性的调节,并且在完全HL适应状态下PsbS的降解至关重要。

更新日期:2020-03-22
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