Faculty of Agriculture, Shinshu University, Minamiminowa, Nagano, Japan.
PLoS One. 2013 Aug 6;8(8):e71581. doi: 10.1371/journal.pone.0071581. Print 2013.
The ultimate goal of this research is to construct a new direct CO2 fixation system using photosystems in living algae. Here, we report light-driven formate production from CO2 by using cyanobacterial photosystem I (PS I). Formate, a chemical hydrogen carrier and important industrial material, can be produced from CO2 by using the reducing power and the catalytic function of formate dehydrogenase (FDH). We created a bacterial FDH mutant that experimentally switched the cofactor specificity from NADH to NADPH, and combined it with an in vitro-reconstituted cyanobacterial light-driven NADPH production system consisting of PS I, ferredoxin (Fd), and ferredoxin-NADP(+)-reductase (FNR). Consequently, light-dependent formate production under a CO2 atmosphere was successfully achieved. In addition, we introduced the NADPH-dependent FDH mutant into heterocysts of the cyanobacterium Anabaena sp. PCC 7120 and demonstrated an increased formate concentration in the cells. These results provide a new possibility for photo-biological CO2 fixation.
本研究的最终目标是利用活藻中的光合系统构建新的直接 CO2 固定系统。在这里，我们报告了利用蓝细菌光系统 I（PSI）从 CO2 光驱动产生甲酸盐。甲酸盐是一种化学氢载体和重要的工业材料，可以通过使用甲酸脱氢酶（FDH）的还原力和催化功能从 CO2 中产生。我们创建了一种细菌 FDH 突变体，实验中将辅因子特异性从 NADH 切换到 NADPH，并将其与由 PS I、铁氧还蛋白（Fd）和铁氧还蛋白-NADP(+)还原酶（FNR）组成的体外重建的蓝细菌光驱动 NADPH 产生系统结合。因此，成功地在 CO2 气氛下实现了光依赖性甲酸盐的产生。此外，我们将 NADPH 依赖性 FDH 突变体引入蓝细菌鱼腥藻属 PCC 7120 的异形胞中，并证明细胞中甲酸盐浓度增加。这些结果为光生物 CO2 固定提供了新的可能性。
