Salt enhances photosystem I content and cyclic electron flow via NAD(P)H dehydrogenase in the halotolerant cyanobacterium Aphanothece halophytica
Salt enhances photosystem I content and cyclic electron flow via NAD(P)H dehydrogenase in the halotolerant cyanobacterium Aphanothece halophytica
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DOI：
10.1071/pp9960321
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发表时间：
1996-01-01
期刊：
影响因子：
--
通讯作者：
Takabe, T
中科院分区：
文献类型：
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作者：
Hibino, T;Lee, BH;Takabe, T
为了揭示光系统对盐胁迫的适应机制，研究了耐盐蓝藻Aphanothece halophytica光系统化学计量和活性对盐胁迫的响应。光合作用O-2的演变是高，即使在高盐度。O-2释放活性随外加NaCl浓度的增加而增加，在1.5M NaCl时达到最大值，然后下降。类似的盐依赖性观察到光系统II活性。另一方面，光系统I活性的增加伴随着盐度的增加。光声测量表明，可观的能量存储由光系统I介导的循环电子流在高盐度。在高盐介质中，观察到通过NAD（P）H-脱氢酶复合物对光系统I反应中心的显着电子捐赠。细胞色素B（6）/f和光系统II的含量在不同盐度条件下几乎不变，而叶绿素a、光系统I、可溶性细胞色素c-553和NAD（P）H-脱氢酶的含量在高盐度条件下增加。这些结果表明，盐特异性地诱导蛋白质水平的增加，涉及光系统I周围的循环电子流，这可能需要一个重要的作用Aphanothece盐生隐杆藻细胞适应高盐度。
To uncover the adaptation mechanisms of photosystems for halotolerance, changes in stoichiometry and activity of photosystems in response to changes of salinities were examined in a halotolerant cyanobacterium, Aphanothece halophytica.. Photosynthetic O-2 evolution was high even at high salinities. O-2 evolution activity increased with increasing external concentration of NaCl, reached a maximum at 1.5 M NaCl, and then decreased. Similar salt dependence was observed for photosystem Ii activity. On the other hand, photosystem I activity increased concomitantly with increase in salinity. Photoacoustic measurements indicated that appreciable energy storage by photosystem I mediated cyclic electron flow at high salinities. Significant electron donation to photosystem I reaction centres through NAD(P)H-dehydrogenase complexes was observed in high salt media. The contents of cytochrome b(6)/f and photosystem II were almost constant under various salinity conditions, whereas the levels of chlorophyll a, photosystem I, soluble cytochrome c-553, and NAD(P)H-dehydrogenase increased in the cells grown with high salinities. These results indicate that salt specifically induces an increase of protein levels involving cyclic electron flow around photosystem I that may entail an important role for adaptation of Aphanothece halophytica cells to high salinities.