Ferritin is required for rapid remodeling of the photosynthetic apparatus and minimizes photo-oxidative stress in response to iron availability in Chlamydomonas reinhardtii
Ferritin is required for rapid remodeling of the photosynthetic apparatus and minimizes photo-oxidative stress in response to iron availability in Chlamydomonas reinhardtii
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DOI：
10.1111/j.1365-313x.2008.03490.x
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发表时间：
2008-07-01
期刊：
影响因子：
7.2
通讯作者：
Hippler, Michael
中科院分区：
文献类型：
--
作者：
Busch, Andreas;Rimbauld, Blandine;Hippler, Michael
铁蛋白是铁稳态的关键参与者，因为它能够储存大量的铁。莱茵衣藻含有两个铁蛋白的核基因（ferr1和ferr2），当衣藻细胞被转移到缺铁条件下时会被诱导。在响应减少铁的可用性，光系统I（PSI）的降解和重塑其光捕获复合物发生。在光合作用不可或缺的光自养条件下，这种活性PSI降解减慢。我们观察到一个强有力的诱导铁蛋白与PSI降解的程度在缺铁。PSI水平可以恢复到正常的24小时内，在铁的补充后，在积累的铁蛋白的费用，表明铁蛋白存储的铁允许快速调整的光合机构相对于铁的可用性。铁蛋白量显著减少的RNAi菌株在铁缺乏下显示PSI降解的显著延迟。此外，这些菌株在强光条件下对光氧化应激更敏感。我们的结论是：（i）铁蛋白是用来缓冲释放的光合复合物的降解铁，（ii）细胞的生理状态决定了用于克服缺铁的影响的策略，（iii）铁蛋白的可用性是重要的快速降解PSI缺铁，和（iv）铁蛋白在光氧化应激条件下起着保护作用。
Ferritin is a key player in the iron homeostasis due to its ability to store large quantities of iron. Chlamydomonas reinhardtii contains two nuclear genes for ferritin (ferr1 and ferr2) that are induced when Chlamydomonas cells are shifted to iron-deficient conditions. In response to the reduced iron availability, degradation of photosystem I (PSI) and remodeling of its light-harvesting complex occur. This active PSI degradation slows down under photo-autotrophic conditions where photosynthesis is indispensable. We observed a strong induction of ferritin correlated with the degree of PSI degradation during iron deficiency. The PSI level can be restored to normal within 24 h after iron repletion at the expense of the accumulated ferritin, indicating that the ferritin-stored iron allows fast adjustment of the photosynthetic apparatus with respect to iron availability. RNAi strains that are significantly reduced in the amount of ferritin show a striking delay in the degradation of PSI under iron deficiency. Furthermore, these strains are more susceptible to photo-oxidative stress under high-light conditions. We conclude that (i) ferritin is used to buffer the iron released by degradation of the photosynthetic complexes, (ii) the physiological status of the cell determines the strategy used to overcome the impact of iron deficiency, (iii) the availability of ferritin is important for rapid degradation of PSI under iron deficiency, and (iv) ferritin plays a protective role under photo-oxidative stress conditions.