Photosynthetic microorganisms such as the cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis) can be exploited for the light-driven synthesis of valuable compounds. Thermodynamically, it is most beneficial to branch-off photosynthetic electrons at ferredoxin (Fd), which provides electrons for a variety of fundamental metabolic pathways in the cell, with the Ferredoxin-NADP+-OxidoReductase (FNR, PetH) being the main target. In order to re-direct electrons from Fd to another consumer, the high electron transport rate between Fd and FNR has to be reduced. Based on our previous in vitro experiments, corresponding FNR-mutants at position FNR_K190 (Wiegand, K., et al.: "Rational redesign of the ferredoxin-NADP-oxido-reductase/ferredoxin-interaction for photosynthesis-dependent H2-production". Biochim Biophys Acta, 2018) have been generated in Synechocystis cells to study their impact on the cellular metabolism and their potential for a future hydrogen producing design cell. Out of two promising candidates, mutation FNR_K190D proved to be lethal due to oxidative stress, while FNR_K190A was successfully generated and characterized: The light induced NADPH formation is clearly impaired in this mutant and it shows also major metabolic adaptations like a higher glucose metabolism as evidenced by quantitative mass spectrometric analysis. These results indicate a high potential for the future use of photosynthetic electrons in engineered design cells - for instance for hydrogen production. They also show substantial differences of interacting proteins in an in vitro environment vs. physiological conditions in whole cells.

中文翻译：

---

重塑集胞藻的光合作用电子运输。PCC 6803用于将来从水中制氢。

光合微生物，例如蓝藻Synechocystis sp.。PCC 6803（Synechocystis）可以用于光驱动合成有价值的化合物。在热力学上，最有利的是在铁氧还蛋白（Fd）处分支光合电子，从而为细胞中各种基本代谢途径提供电子，其中铁氧还蛋白-NADP +-氧化还原酶（FNR，PetH）是主要靶标。为了将电子从Fd重定向到另一个使用者，必须降低Fd和FNR之间的高电子传输速率。根据我们先前的体外实验，在FNR_K190位置处对应的FNR突变体（Wiegand，K.等人：“铁氧还蛋白-NADP-氧化还原酶/铁氧还蛋白相互作用的合理重新设计，用于光合作用依赖性H2的产生”。 Biochim Biophys Acta，2018年）已在集胞囊藻细胞中产生，以研究它们对细胞代谢的影响以及未来产氢设计细胞的潜力。在两个有前途的候选基因中，突变型FNR_K190D被证明是由于氧化应激而致死的，而成功生成并表征了FNR_K190A：在该突变型中，光诱导的NADPH形成明显受损，并且还显示出主要的代谢适应性，例如更高的葡萄糖代谢通过定量质谱分析。这些结果表明光合电子在工程设计电池中的未来使用潜力很大，例如用于制氢。它们还显示出体外环境中相互作用蛋白与全细胞中生理条件之间的显着差异。