Acknowledgements
We thank members of Pilong Li’s lab for helpful discussions and kindly provision of plasmids. We also thank Dr. Peng Li for his team and lab training and members of iGEM Tsinghua team (2018) for their guidance in brainstorming. This work was supported by Tsinghua University Initiative Scientific Research Program, Tsinghua Xuetang Program, and Student Research Training Program. This research was also financially supported by grants from the Ministry of Science and Technology of China (Grant No. 2018YFA0900200), National Natural Science Foundation of China (Grant No. 31961133019; No. 21761132013; No. 31870859), and Center of Life Sciences of Tsinghua-Peking University.