Novel optogenetic tools based on heliorhodopsins

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K15900
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 46010:Neuroscience-general-related
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Hososhima Shoko 名古屋工業大学, 工学(系)研究科(研究院), 研究員 (90847914)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 微生物ロドプシン / ヘリオロドプシン / チャネルロドプシン / 光遺伝学 / オプトジェネティクス

Outline of Final Research Achievements

Rhodopsins convert light into signals and energy in animals and microbes. Heliorhodopsins (HeRs), a recently discovered new rhodopsin family, are widely present in archaea, bacteria, unicellular eukaryotes, and giant viruses, but their function remains unknown. In this study, we revealed that a viral HeR from Emiliania huxleyi virus 202 (V2HeR3) is a light-activated proton transporter. Furthermore, the cryptophyte algae, Guillardia theta, possesses 46 genes that are homologous to microbial rhodopsins. Five of these are functionally light-gated cation channelrhodopsins (GtCCR1-5), which are phylogenetically distinct from chlorophyte channelrhodopsins (ChRs) such as ChR2 from Chlamydomonas reinhardtii. In this study, we investigated the ion channel properties of these five CCRs and compared them with ChR2 and other ChRs widely used in optogenetics. We revealed that GtCCR1-5 have different light sensitivities, and that GtCCR4 has a high light sensitivity.

Free Research Field

生物物理

Academic Significance and Societal Importance of the Research Achievements

円石藻ウイルスの持つヘリオロドプシンが、光依存的にプロトンを輸送することを世界に先駆けて明らかにした。本研究はヘリオロドプシンを膜配向制御に利用しようと開始したため、その機能が明らかになったことは想定外の発見であった。円石藻は海洋中の二酸化炭素を固定するため、海洋の炭素循環に重要な役割を担っている。円石藻の大量発生は白潮を発生させ、海洋の環境悪化を引き起こす。白潮は円石藻ウイルスの感染により崩壊することが知られているが、本研究からヘリオロドプシンが光を使って円石藻の崩壊を促す可能性が示唆され、地球環境の観点からも注目された。