Diversity in photosynthetic electron transport under CO2-limitation: the cyanobacterium Synechococcus sp. PCC7002 and green alga Chlamydomonas reinhardtii drive an O2-dependent alternative electron flow and non-photochemical quenching of chlorophyll fluor
Diversity in photosynthetic electron transport under CO2-limitation: the cyanobacterium Synechococcus sp. PCC7002 and green alga Chlamydomonas reinhardtii drive an O2-dependent alternative electron flow and non-photochemical quenching of chlorophyll fluor
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CO2限制下光合电子传递的多样性：蓝藻聚球藻属。
DOI：
10.1007/s11120-016-0253-y
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
and C. Miyake
中科院分区：
文献类型：
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作者：
G. Shimakawa;S. Akimoto;Y. Ueno;A. Wada;K. Shaku;Y. Takahashi;and C. Miyake
一些蓝藻（但不是全部）在二氧化碳限制的光合作用过程中会产生替代电子流（AEF）。例如，集胞藻属 (Synechocystissp)。 PCC 6803 (S. 6803) 表现出 AEF，但细长聚球藻 (Synechococcus elongatussp.) 表现出 AEF。 PCC 7942 没有。这种差异是由于 S.6803 中存在黄二铁 2 和 4 蛋白 (FLV2/4)，其催化向 O2 提供电子。在这项研究中，我们在海洋蓝藻聚球藻中观察到低[CO2]诱导的AEF。缺少 FLV2/4 的 PCC 7002。与 S.6803 中由 FLV2/4 介导的 AEF 相比，AEF 对 O2 显示出高亲和力，并且可以在极低的 [O2]（约几个 µM O2）下进行。此外，从 CO2 饱和到 CO2 限制的光合作用的转变导致 PSI 优先激发到 PSII，并增加叶绿素荧光的非光化学猝灭。我们发现模型绿藻莱茵衣藻也具有 O2 依赖性 AEF，显示出与 S. 7002 中相同的 O2 亲和力。这些数据代表了蓝藻和绿藻中驱动 AEF 的不同分子机制。在本文中，我们进一步讨论了蓝藻和绿藻光合作用中二氧化碳限制策略的多样性、进化和生理功能。
Some cyanobacteria, but not all, experience an induction of alternative electron flow (AEF) during CO2-limited photosynthesis. For example,Synechocystissp. PCC 6803 (S. 6803) exhibits AEF, butSynechococcus elongatussp. PCC 7942 does not. This difference is due to the presence of flavodiiron 2 and 4 proteins (FLV2/4) in S. 6803, which catalyze electron donation to O2. In this study, we observed a low-[CO2] induced AEF in the marine cyanobacteriumSynechococcussp. PCC 7002 that lacks FLV2/4. The AEF shows high affinity for O2, compared with AEF mediated by FLV2/4 in S. 6803, and can proceed under extreme low [O2] (about a few µM O2). Further, the transition from CO2-saturated to CO2-limited photosynthesis leads a preferential excitation of PSI to PSII and increased non-photochemical quenching of chlorophyll fluorescence. We found that the model green algaChlamydomonas reinhardtiialso has an O2-dependent AEF showing the same affinity for O2as that in S. 7002. These data represent the diverse molecular mechanisms to drive AEF in cyanobacteria and green algae. In this paper, we further discuss the diversity, the evolution, and the physiological function of strategy to CO2-limitation in cyanobacterial and green algal photosynthesis.