In the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, glucose 6-phosphate dehydrogenase (G6PDH) plays an important role in producing the power for reducing nitrogenase under light conditions. Our previous study showed that thioredoxin suppresses G6PDH by reducing its activator protein OpcA, implying that G6PDH is inactivated under light conditions because thioredoxins are considered to be reduced by the photosynthetic electron transport system in cyanobacteria. To address how Anabaena sp. PCC 7120 maintains G6PDH activity even under light conditions when nitrogen fixation occurs, we investigated the redox regulation system in vegetative cells and specific nitrogen-fixing cells named heterocysts, individually. We found that thioredoxin-target proteins were more oxidized in heterocysts than in vegetative cells under light conditions. Alterations in the redox regulation mechanism of heterocysts may affect the redox states of thioredoxin-target proteins, including OpcA, so that G6PDH is activated in heterocysts even under light conditions.

中文翻译：

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硫氧还蛋白靶标在蓝藻鱼腥藻的异囊中被调节。PCC 7120以与光无关的方式。

在固氮蓝细菌鱼腥藻中。PCC 7120中的6-磷酸葡萄糖脱氢酶（G6PDH）在产生光条件下还原固氮酶的能力中起着重要作用。我们先前的研究表明，硫氧还蛋白通过减少其激活蛋白OpcA来抑制G6PDH，这意味着G6PDH在光照条件下会失活，因为硫氧还蛋白被蓝细菌的光合作用电子传输系统还原了。为了解决鱼腥藻如何。PCC 7120甚至在光照条件下发生固氮时也能维持G6PDH活性，我们分别研究了营养细胞和特定的固氮细胞异种囊肿中的氧化还原调节系统。我们发现，在光照条件下，异质囊中的硫氧还蛋白靶蛋白比营养细胞中的氧化程度更高。