@article {Kashiyama2019, title = {Taming chlorophylls by early eukaryotes underpinned algal interactions and the diversification of the eukaryotes on the oxygenated Earth}, journal = {The ISME Journal}, year = {2019}, note = {Publisher: Springer US tex.mendeley-tags: RCC164,RCC22,RCC24,RCC375,RCC916}, month = {feb}, pages = {1}, abstract = {Extant eukaryote ecology is primarily sustained by oxygenic photosynthesis, in which chlorophylls play essential roles. The exceptional photosensitivity of chlorophylls allows them to harvest solar energy for photosynthesis, but on the other hand, they also generate cytotoxic reactive oxygen species. A risk of such phototoxicity of the chlorophyll must become particularly prominent upon dynamic cellular interactions that potentially disrupt the mechanisms that are designed to quench photoexcited chlorophylls in the phototrophic cells. Extensive examination of a wide variety of phagotrophic, parasitic, and phototrophic microeukaryotes demonstrates that a catabolic process that converts chlorophylls into nonphotosensitive 132,173-cyclopheophorbide enols (CPEs) is phylogenetically ubiquitous among extant eukaryotes. The accumulation of CPEs is identified in phagotrophic algivores belonging to virtually all major eukaryotic assemblages with the exception of Archaeplastida, in which no algivorous species have been reported. In addition, accumulation of CPEs is revealed to be common among phototrophic microeukaryotes (i.e., microalgae) along with dismantling of their secondary chloroplasts. Thus, we infer that CPE-accumulating chlorophyll catabolism (CACC) primarily evolved among algivorous microeukaryotes to detoxify chlorophylls in an early stage of their evolution. Subsequently, it also underpinned photosynthetic endosymbiosis by securing close interactions with photosynthetic machinery containing abundant chlorophylls, which led to the acquisition of secondary chloroplasts. Our results strongly suggest that CACC, which allowed the consumption of oxygenic primary producers, ultimately permitted the successful radiation of the eukaryotes throughout and after the late Proterozoic global oxygenation.}, keywords = {Biochemistry, Biogeochemistry, Cellular microbiology, microbial ecology, RCC164, RCC22, RCC24, RCC375, RCC916}, issn = {1751-7362}, doi = {10.1038/s41396-019-0377-0}, url = {http://www.nature.com/articles/s41396-019-0377-0}, author = {Kashiyama, Yuichiro and Yokoyama, Akiko and Shiratori, Takashi and Hess, Sebastian and Not, Fabrice and Bachy, Charles and Gutierrez-Rodriguez, Andres and Kawahara, Jun and Suzaki, Toshinobu and Nakazawa, Masami and Ishikawa, Takahiro and Maruyama, Moe and Wang, Mengyun and Chen, Man and Gong, Yingchun and Seto, Kensuke and Kagami, Maiko and Hamamoto, Yoko and Honda, Daiske and Umetani, Takahiro and Shihongi, Akira and Kayama, Motoki and Matsuda, Toshiki and Taira, Junya and Yabuki, Akinori and Tsuchiya, Masashi and Hirakawa, Yoshihisa and Kawaguchi, Akane and Nomura, Mami and Nakamura, Atsushi and Namba, Noriaki and Matsumoto, Mitsufumi and Tanaka, Tsuyoshi and Yoshino, Tomoko and Higuchi, Rina and Yamamoto, Akihiro and Maruyama, Tadanobu and Yamaguchi, Aika and Uzuka, Akihiro and Miyagishima, Shinya and Tanifuji, Goro and Kawachi, Masanobu and Kinoshita, Yusuke and Tamiaki, Hitoshi} }