Yang Fan, Zhang Junli, Cai Zhen, Zhou Jie, Li Yin
CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
University of the Chinese Academy of Sciences, Beijing, China.
AMB Express. 2021 May 8;11(1):65. doi: 10.1186/s13568-021-01224-6.
The oxygenase activity of Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) converts ribulose-1,5-bisphosphate (RuBP) into 2-phosphoglycolate, which in turn channels into photorespiration, resulting in carbon and energy loss in higher plants. We observed that glycolate can be accumulated extracellularly when two genes encoding the glycolate dehydrogenase of cyanobacteria Synechocystis sp. PCC 6803 were inactivated. This inspired us to explore the oxygenase function of Rubisco for production of glycolate, an important industrial chemical, from CO by engineered cyanobacteria. Since the oxygenase activity of Rubisco is generally low in CO-rich carboxysome of cyanobacteria, we introduced Form II Rubisco, which cannot be assembled in carboxysome, into the cytoplasm of cyanobacteria. Heterologous expression of a Form II Rubisco from endosymbiont of tubeworm Riftia pachyptila (RPE Rubisco) significantly increased glycolate production. We show that the RPE Rubisco is expressed in the cytoplasm. Glycolate production increased upon addition of NaHCO but decreased upon supplying CO. The titer of glycolate reached 2.8 g/L in 18 days, a 14-fold increase compared with the initial strain with glycolate dehydrogenase inactivated. This is also the highest glycolate titer biotechnologically produced from CO ever reported. Photosynthetic production of glycolate demonstrated the oxygenase activity of Form II Rubisco can be explored for production of chemicals from CO.
1,5-二磷酸核酮糖羧化酶/加氧酶（Rubisco）的加氧酶活性将1,5-二磷酸核酮糖（RuBP）转化为2-磷酸乙醇酸，进而进入光呼吸途径，导致高等植物中的碳和能量损失。我们观察到，当编码蓝藻集胞藻PCC 6803乙醇酸脱氢酶的两个基因失活时，乙醇酸可以在细胞外积累。这启发我们探索Rubisco的加氧酶功能，以便通过工程蓝藻从CO生产重要的工业化学品乙醇酸。由于蓝藻富含CO的羧酶体中Rubisco的加氧酶活性通常较低，我们将不能组装在羧酶体中的II型Rubisco引入蓝藻细胞质中。来自管虫巨型硫细菌内共生体的II型Rubisco（RPE Rubisco）的异源表达显著提高了乙醇酸的产量。我们表明RPE Rubisco在细胞质中表达。添加NaHCO时乙醇酸产量增加，但供应CO时产量下降。18天内乙醇酸滴度达到2.8 g/L，与乙醇酸脱氢酶失活的初始菌株相比增加了14倍。这也是有史以来报道的通过生物技术从CO生产的最高乙醇酸滴度。乙醇酸的光合生产表明，可以探索II型Rubisco的加氧酶活性用于从CO生产化学品。
