Depka B, Jahns P, Trebst A
Biochemie der Pflanzen, Ruhr-Universität Bochum, Germany.
FEBS Lett. 1998 Mar 13;424(3):267-70. doi: 10.1016/s0014-5793(98)00188-4.
The carotenoid composition was investigated during enhanced D1 protein turnover in Chlamydomonas reinhardtii exposed to high light. After 2 h of high light there was no loss of the D1 protein yet. However, the beta-carotene content was significantly reduced. In parallel, an increase of the zeaxanthin content was found, which was higher than can be accounted for by the light-induced de-epoxidation of violaxanthin in the xanthophyll cycle reactions. We therefore assume that beta-carotene of photosystem II (PS II) is hydroxylated to zeaxanthin under high light stress. Inhibitors of carotene biosynthesis led to the loss of both PS II activity and D1 protein, indicating the requirement of beta-carotene synthesis for the reassembly of PS II in high light. Diuron blocked D1 protein as well as beta-carotene turnover. In the presence of chloramphenicol -- which allows just one turnover of the D1 protein -- 15% of the total beta-carotene was lost, calculated to be two beta-carotene.
在高光条件下莱茵衣藻中D1蛋白周转增强的过程中，对类胡萝卜素组成进行了研究。高光照射2小时后，D1蛋白尚未损失。然而，β-胡萝卜素含量显著降低。同时，发现玉米黄质含量增加，其增加量高于叶黄素循环反应中光诱导紫黄质脱环氧化所能解释的量。因此，我们推测在高光胁迫下，光系统II（PS II）的β-胡萝卜素会羟基化为玉米黄质。类胡萝卜素生物合成抑制剂导致PS II活性和D1蛋白均丧失，这表明在高光条件下PS II重新组装需要β-胡萝卜素的合成。敌草隆阻断了D1蛋白以及β-胡萝卜素的周转。在氯霉素存在的情况下（氯霉素仅允许D1蛋白周转一次），总β-胡萝卜素的15%损失，经计算为两个β-胡萝卜素。
