Dr. SHEN Jian-Ren

Dr. SHEN Jian-Ren, Professor from the Institute of Botany, CAS, paid a visit to Institute of Hydrobiology, Chinese Academy of Sciences (IHB) and gave a lecture entitled "Atomic structure of photosystem II membrane-protein complex and the mechanism of photosynthetic water-splitting."

Photosystem II (PSII) is a multi-subunit membrane protein complex consisting of 20 subunits with a total molecular mass of 350 kDa, which catalyzes the light-induced water splitting reaction, resulting in the generation of electrons, protons and molecular oxygen. This reaction is extremely important to all oxygenic life forms on the earth as it provides oxygen to the atmosphere and converts light energy into biologically useful chemical energy, both indispensable for sustaining life on the earth.

In order to reveal the molecular mechanisms of water-splitting, Dr. Shen’s group have analyzed the structure of PSII at 1.9 ？ resolution, making PSII the largest membrane-protein complex whose structure has been solved beyond 2.0 ？ resolution. Their analysis revealed not only the detailed structure of the whole PSII dimer complex including nearly 2,800 water molecules, but also elucidated for the first time the detailed structure of a Mn₄CaO₅-cluster, the catalytic center for water-splitting.

Dr. Shen’s results showed that the Mn₄CaO₅-cluster is organized in a distorted chair form, implying that it has a high structural flexibility, enabling it easier to undergo structural changes occurring in the water-splitting reaction. Based on these and their related studies, Dr. Shen discussed the mechanism of light-induced water-splitting that may have important implications for synthesis of artificial catalysts for water-splitting, an important task in the studies of artificial photosynthesis. In view of the importance of light-induced water-splitting, the structural analysis of PSII has been chosen by AAAS Science as one of the runners-up for "Breakthroughs of the year" for 2011.

Dr. Shen is a professor in the division of Bioscience, Okayama University, Japan and also in the Institute of Botany, CAS, China, who was chosen in the Recruitment Program of Global Experts in 2012.