Does evolution increase pigment protein?

May 18, 2020

Three-dimensional structure of photosystem I-light-harvesting pigmentprotein supercomplex of diatoms

A joint research group of Okayama University, the University of Tsukuba, the RIKEN Center for Sustainable Resource Science, Kyoto University, the University of Hyogo, the National Institute for Basic Biology, and Kobe University successfully analyzed the three-dimensional structure of photosystem I-light-harvesting pigment-protein supercomplex of marine diatoms using cryoelectron microscopy. The results reveled that photosynthetic organisms regulate the number and binding pattern of light-harvesting pigment protein in order to adapt to a variety of photoenvironments.

The achievement of this study provides information to answer the questions of why photosynthetic organisms have variations in colors and how they have expanded their habitats. The variation in color is part of the survival strategies for photosynthetic organisms. Diatoms have been able to expand their habitats because their reddish color enables them to efficiently use the limited light energy transmitted through the water. The study showed that the light-harvesting pigment protein that binds to the photochemical system I protein of diatoms is greatly different from that of red algae living in relatively deep seas and green plants that live on land. The achievement provides knowledge to illustrate the variations of light-harvesting pigment proteins in photosynthetic organisms and also to solve the evolutionary question, "why do photosynthetic organisms have ifferent colors in appearance?"

The structure shown in this study is expected to provide a guideline on the design of molecular arrangement necessary for the conversion of solar energy into electrical energy using the spectral components of sunlight. The findings on the structure obtained in this study, along with the existing knowledge on the structures of other photosynthesis devices, are expected to contribute to development of devices for energy use based on the selective use of sunlight’s spectral components.

Original article
Nature Communications doi:10.1038/s41467-020-16324-3
R. Nagao, K. Kato, K. Ifuku, T. Suzuki, M. Kumazawa, I. Uchiyama, Y. Kashino, N. Dohmae, S. Akimoto, J.-R. Shen, N. Miyazaki, F. Akita,
"Structural basis for assembly and function of a diatom photosystem I-light harvesting supercomplex".
Naoshi Dohmae
Unit Leader
Biomolecular Characterization Unit