Botanical Institute, Christian-Albrechts-University, 24118, Kiel, Germany.
Institute of Geosciences, Christian-Albrechts-University, 24118, Kiel, Germany.
Sci Rep. 2018 Apr 17;8(1):6083. doi: 10.1038/s41598-018-24430-y.
Cyanobacteria provide all components for sunlight driven biohydrogen production. Their bidirectional NiFe-hydrogenase is resistant against low levels of oxygen with a preference for hydrogen evolution. However, until now it was unclear if its catalytic efficiency can keep pace with the photosynthetic electron transfer rate. We identified NikKLMQO (sll0381-sll0385) as a nickel transporter, which is required for hydrogen production. ICP-MS measurements were used to quantify hydrogenase molecules per cell. We found 400 to 2000 hydrogenase molecules per cell depending on the conditions. In-vivo turnover frequencies of the enzyme ranged from 62 H/s in the wild type to 120 H/s in a mutant during photohydrogen production. These frequencies are above maximum in-vivo photosynthetic electron transfer rates of 47 e/s (equivalent to 24 H/s). They are also above those of existing in-vitro systems working with unlimited electron supply and show that in-vivo photohydrogen production is limited by electron delivery to the enzyme.
蓝藻为阳光驱动的生物制氢提供所有组件。它们的双向 NiFe-氢化酶对低氧水平具有抗性，并且优先进行氢的析出。然而，直到现在，其催化效率是否能跟上光合作用电子转移速率还不清楚。我们鉴定出 NikKLMQO（sll0381-sll0385）作为镍转运蛋白，其对于产氢是必需的。我们使用 ICP-MS 测量来定量每个细胞中的氢化酶分子。我们发现，根据条件的不同，每个细胞中有 400 到 2000 个氢化酶分子。在光生物制氢过程中，该酶的体内转化频率在野生型中为 62 H/s，在突变体中为 120 H/s。这些频率高于最大的体内光合作用电子转移率 47 e/s（相当于 24 H/s）。它们也高于那些具有无限电子供应的现有体外系统，表明体内光生物制氢受到电子向酶的传递限制。
