2025-10-15 東京大学
紫外光に応答して、イオンを輸送するアプソモナド類のロドプシン
<関連情報>
- https://www.issp.u-tokyo.ac.jp/maincontents/news2.html?pid=28457
- https://www.issp.u-tokyo.ac.jp/news/wp-content/uploads/2025/10/press_1015_uv-rhodopsin.pdf
- https://www.pnas.org/doi/10.1073/pnas.2510619122
アプソモナス・ロドプシン:紫外線から青色光を吸収するロドプシンチャネルの新しいファミリー Apusomonad rhodopsins: A new family of ultraviolet to blue light–absorbing rhodopsin channels
Luis Javier Galindo, Shunki Takaramoto, Takashi Nagata, +3 , and Keiichi Inoue
Proceedings of the National Academy of Sciences Published:October 13, 2025
DOI:https://doi.org/10.1073/pnas.2510619122
Significance
Protists are well known to harbor diverse families of retinal-binding photoreceptive proteins known as microbial rhodopsins. However, less is known about the overall diversity of microbial rhodopsins in heterotrophic flagellates (HFs), an understudied and highly diverse protist category. Apusomonads are a clade of HFs sister to Opisthokonta (animals, fungi, and protist relatives). We have found genes of a group of phylogenetically distinct microbial rhodopsins in apusomonads, ApuRs. ApuRs absorb near UV/violet or blue light and are a new class of rhodopsin channels. ApuRs are the first rhodopsin channels capable of responding to UV light, thus expanding our understanding of the photobiology of protists and pave the way to development of novel UV-based biotechnological applications.
Abstract
Apusomonads are sediment-dwelling bacterivorous protists that are sister to all Opisthokonta. They have been found to show a negative phototactic response to blue light, mediated by an as-yet unidentified photoreceptive system. Here, by screening available apusomonad omics data we found genes of a distinct group of microbial rhodopsins, apusomonad rhodopsins (ApuRs). ApuRs, heterologously expressed in mammalian cells, absorbed near-UV or violet light, suggesting that ApuRs could be involved in apusomonads’ photoavoidance response toward short-wavelength light. Electrophysiological measurements indicate that ApuRs are anion-selective rhodopsin channels which evolved independently of the family of channelrhodopsins widespread in other unicellular eukaryotes. In ApuRs, channel opening is triggered by photoisomerization of the retinal from its all-trans form to 13-cis and 11-cis forms. We found that intracellular proton transfer is involved in channel opening and determines the channel’s open/close kinetics. These findings expand our understanding of the photobiology of heterotrophic flagellates and demonstrate that UV-absorbing ApuRs are in fact the most blue-shifted rhodopsin channels known to date.
