On October 23, Nature published a three-dimensional structural analysis paper on key enzymes for chlorophyll biosynthesis. The results were jointly completed by the Institute of Biotechnology of the Chinese Academy of Agricultural Sciences, Manchester University and Shanghai Jiaotong University. For the first time, this study analyzed the three-dimensional crystal structure of the light-dependent protochlorophyllide oxidoreductase (LPOR), a key enzyme of chlorophyll biosynthesis, and unveiled the true structure of the biological transformation “valve” of the ultimate energy source of photosynthesis. The structural basis and the kinetic mechanism of light-driven enzymes fill the gaps in the three-dimensional structure of key enzymes for chlorophyll biosynthesis in the photosynthesis pathway in the past 100 years in the world, with a "milestone" type.

“Everything grows by the sun”, and the energy used in life on Earth is directly or indirectly transformed through photosynthesis. According to Dr. Cheng Qi, the corresponding author of the paper, LPOR is a key enzyme for chlorophyll synthesis in cyanobacteria, algae and multicellular plants. It is directly related to the greening ability of yellowing seedlings and is essential for the growth and development of green plants. The discovery of this key enzyme has been nearly a hundred years, and the analysis of its structure and mechanism of action is of great significance to the theory and application of photosynthesis. It is one of the major scientific issues to besolved in this field.

This study reports the crystal structure of LPOR enzyme monomer and LPOR-NADPH protein complex at different diffraction rates. Through the analysis of the crystal structure of LPOR and the accurate modeling of LPOR-NADPH- protochlorophyllide ternary complex, the precise process of LPOR protein catalyzing the conversion of protochlorophyllide to chlorophyllide was clarified, how to use light energy to drive plants. Enzyme catalysis provides important information and paves the way for quantitative calculation and analysis of quantitative energy conversion reactions. It has great significance for the photocatalytic chemical and biological catalysts and the engineering design of related small molecule inhibitors.

By Wang Youhua (wangyouhua@caas.cn)