Native 3-D Structure of Photosystem II at 1.95 A Resolution Revealed
November 27, 2014
Researchers from Okayama University and RIKEN have found the native structure of photosystem II at a resolution of 1.95 A using femtosecond X-ray pulses.
The findings were published online November 26, 2014 in the journal Nature.
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13991.html
Photosynthesis converts light energy into biologically useful chemical energy vital to life on Earth. The initial reaction of photosynthesis takes place in photosystem II (PSII), a membrane protein complex that catalyses the photo-oxidation of water into dioxygen. The structure of PSII was previously observed using X-ray diffraction at 1.9 A resolution, which revealed that the catalytic center is a Mn4CaO5-cluster coordinated by a well defined protein environment. However, the manganese cations in the catalytic cluster are easily reduced by X-ray irradiation, and thus the Mn-Mn distances determined by X-ray diffraction may have been slightly different from the actual distances.
The research group has observed a ‘radiation-damage-free’ structure of PSII from Thermosynechococcus vulcanus at a resolution of 1.95 angstroms using femtosecond X-ray pulses of the SPring-8 angstrom compact free-electron laser (SACLA) and highly isomorphous PSII crystals. Compared with the structure observed from XRD, the Mn4CaO5-cluster in the X-ray free electron laser-observed structure has Mn-Mn distances that are shorter by 0.1-0.3 angstroms and reflects the actual structure of the catalyst.
These findings provide a structural basis for the mechanism of oxygen evolution. This native structure could lead to a blueprint for the design of artificial catalysts for water oxidation.
Contact Information:
Mototaka Senda, Ph.D.
US Representative
Intellectual Property Office, Organization for Research Promotion and Collaboration, Okayama University
Fremont, California USA
TEL: 1-510-797-0907
Email: takasenda@okayama-u.ac.jp
Shen Jian-Ren, Ph.D.
Graduate School of Natural Science and Technology, Okayama University, Okayama Japan