A research group led by Tatsuya Tsuchida (at the time of the research) , Associate Professor Takahiro Soeta and Professor Yutaka Ukaji at Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, in collaboration with research groups at Toyohashi University of Technology, Tokyo University of Pharmacy and Life Sciences, and others, had clarified the mechanism of operation of the photosensor that regulates photosynthesis for the first time in the world.
Cyanobacteria sense the presence of green and red light and regulate the composition of their antenna molecules to more efficiently absorb photosynthetic light. Although this phenomenon has been known for more than a century, the detailed mechanism of how they distinguish between green and red light was not understood. In this study, they focused on the cyanobacteriochrome RcaE and analyzed the structure and details of the green light-absorbing (Pg) state of RcaE. By comparing the structure of RcaE with that of the red-absorbing state (Pr), which was previously published by this research group, they were able to elucidate how the photoswitch molecule senses the green and red states.
The results of this study are expected to contribute to the understanding of the environmental response mechanism of photosynthesis and to the advancement of applied research such as photogenetics.
These results were published in the international journal Science Advances on June 12, 2024 at 14:00 (EST).
【Key points of this research】
- Photosynthetic cyanobacteria switch the color of the light they use for photosynthesis in order to optimize photosynthesis in response to different light. For example, some cyanobacteria can switch from red light photosynthesis to green light photosynthesis and vice versa. This phenomenon has been known for over a century, but the detailed mechanism of how they distinguish between green and red light was not understood.
- In this study, the structure of the "photoswitch molecule" used by cyanobacteria to distinguish red light from green light was clarified when green light is sensed via several methods including chemical synthesis of the regioselectively 15N-labeled chromophores. By comparing the structure of the photoswitch molecule when sensing red light with the structure of the photoswitch molecule when sensing green light, which was previously reported by the same group, the researchers were able to elucidate how the photoswitch molecule senses green and red light. The mechanism revealed is completely new and has not been reported in other photoswitches in other organisms such as plants.
- These results are expected not only to elucidate how photosynthetic organisms flexibly adapt to changes in their environment, but also to provide better tools for optogenetics, the study of how light controls the functions of organisms.
Figure 1: Regulation of light color acclimation by cyanobacteriochromes RcaE.
Click here to see the press release【Japanese only】
Journal：Science Advances
Researcher's Information： Yutaka Ukaji
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