Berepiki Adokiye, Hitchcock Andrew, Moore C Mark, Bibby Thomas S
Ocean and Earth Sciences, National Oceanography Centre, University of Southampton , Southampton, United Kingdom.
Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield, United Kingdom.
ACS Synth Biol. 2016 Dec 16;5(12):1369-1375. doi: 10.1021/acssynbio.6b00100. Epub 2016 Aug 1.
Increasing the efficiency of the conversion of light energy to products by photosynthesis represents a grand challenge in biotechnology. Photosynthesis is limited by the carbon-fixing enzyme Rubisco resulting in much of the absorbed energy being wasted as heat or fluorescence or lost as excess reductant via alternative electron dissipation pathways. To harness this wasted reductant, we engineered the model cyanobacterium Synechococcus PCC 7002 to express the mammalian cytochrome P450 CYP1A1 to serve as an artificial electron sink for excess electrons derived from light-catalyzed water-splitting. This improved photosynthetic efficiency by increasing the maximum rate of photosynthetic electron flow by 31.3%. A simple fluorescent assay for CYP1A1 activity demonstrated that the P450 was functional in the absence of its native reductase, that activity was light-dependent and scaled with irradiance. We show for the first time in live cells that photosynthetic reductant can be redirected to power a heterologous cytochrome P450. Furthermore, Synechococcus PCC 7002 expressing CYP1A1 degraded the herbicide atrazine, which is a widespread environmental pollutant.
提高光合作用将光能转化为产物的效率是生物技术领域的一项重大挑战。光合作用受限于碳固定酶核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco），导致大量吸收的能量以热量或荧光形式浪费，或通过替代电子耗散途径以过量还原剂形式损失。为了利用这些浪费的还原剂，我们对模式蓝藻聚球藻PCC 7002进行工程改造，使其表达哺乳动物细胞色素P450 CYP1A1，作为光催化水分解产生的过量电子的人工电子阱。这通过将光合电子流的最大速率提高31.3%，提高了光合效率。一种用于CYP1A1活性的简单荧光测定法表明，该细胞色素P450在没有其天然还原酶的情况下具有功能，其活性依赖于光并与辐照度成比例。我们首次在活细胞中证明光合还原剂可被重新定向以驱动异源细胞色素P450。此外，表达CYP1A1的聚球藻PCC 7002降解了除草剂阿特拉津，阿特拉津是一种广泛存在的环境污染物。
