Inhibition of respiration and nitrate assimilation enhances photohydrogen evolution under low oxygen concentrations in Syneehocystis sp PCC 6803
Inhibition of respiration and nitrate assimilation enhances photohydrogen evolution under low oxygen concentrations in Syneehocystis sp PCC 6803
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DOI：
10.1016/j.bbabio.2006.12.003
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发表时间：
2007-02-01
影响因子：
4.3
通讯作者：
Appel, Jens
中科院分区：
文献类型：
--
作者：
Gutthann, Franziska;Egert, Melanie;Appel, Jens
在蓝藻细胞膜中，光合作用、光反应和呼吸作用相互交织。结果表明，集胞藻PCC 6803的单一氢化酶与光反应有关。我们对呼吸电子传递复合物缺失突变体的氢化酶活性、发酵产氢和光产氢进行了测定。所有的单，双和三重突变体的三个终端呼吸氧化酶和ndhB-突变体没有一个功能复杂的我进行了研究。通过在黑暗中应用厌氧条件激活氢化酶后，在光照开始时测量氢的产生。在这些条件下，呼吸能力和产生的光氢量被发现是负相关的。特别是与野生型细胞相比，醌醇氧化酶的缺乏诱导了氢化酶活性的增加和光下氢产量的增加。我们的研究结果支持氢化酶以及醌醇氧化酶功能的电子阀在低氧浓度。当光系统11和I（PSII和PSI）的活性不平衡时，或者在光反应以比暗反应更高的速度进行的情况下，氢化酶是防止PSI的受体侧限制所必需的，并且醌醇氧化酶是防止质体醌库（PSII的受体侧）过度还原所必需的。除了氧气，硝酸盐同化被认为是一个重要的电子汇。硝酸还原酶的抑制导致发酵产氢量增加以及光氢量增加。(c)2006 Elsevier B. V.保留所有权利。
In cyanobacterial membranes photosynthetic light reaction and respiration are intertwined. It was shown that the single hydrogenase of Synechocystis sp. PCC 6803 is connected to the light reaction. We conducted measurements of hydrogenase activity, fermentative hydrogen evolution and photohydrogen production of deletion mutants of respiratory electron transport complexes. All single, double and triple mutants of the three terminal respiratory oxidases and the ndhB-mutant without a functional complex I were studied. After activating the hydrogenase by applying anaerobic conditions in the dark hydrogen production was measured at the onset of light. Under these conditions respiratory capacity and amount of photohydrogen produced were found to be inversely correlated. Especially the absence of the quinol oxidase induced an increased hydrogenase activity and an increased production of hydrogen in the light compared to wild type cells. Our results support that the hydrogenase as well as the quinol oxidase function as electron valves under low oxygen concentrations. When the activities of photosystem 11 and I (PSII and PSI) are not in equilibrium or in case that the light reaction is working at a higher pace than the dark reaction, the hydrogenase is necessary to prevent an acceptor side limitation of PSI, and the quinol oxidase to prevent an overreduction of the plastoquinone pool (acceptor side of PSII). Besides oxygen, nitrate assimilation was found to be an important electron sink. Inhibition of nitrate reductase resulted in an increased fermentative hydrogen production as well as higher amounts of photohydrogen. (c) 2006 Elsevier B.V. All rights reserved.