Comparative Studies of the Fluorescence Properties of Microbial Rhodopsins: Spontaneous Emission Versus Photointermediate Fluorescence

Keiichi Kojima, Rika Kurihara, Masayuki Sakamoto, Tsukasa Takanashi, Hikaru Kuramochi, Xiao Min Zhang, Haruhiko Bito, Tahei Tahara, Yuki Sudo

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Rhodopsins are seven-transmembrane photoreceptor proteins that bind to the retinal chromophore and have been utilized as a genetically encoded voltage indicator (GEVI). So far, archaerhodopsin-3 (AR3) has been successfully used as a GEVI, despite its low fluorescence intensity. We performed comparative and quantitative fluorescence analyses of 15 microbial rhodopsins to explore these highly fluorescent molecules and to clarify their fluorescence mechanism. These rhodopsins showed a wide range of fluorescence intensities in mouse hippocampal neurons. Some of them, GR, HwBR, IaNaR, MR, and NpHR, showed fluorescence intensities comparable with or higher than that of AR3, suggesting their potential for GEVIs. The fluorescence intensity in neurons correlated with that of the bright fluorescent photointermediate such as a Q-intermediate (R = 0.75), suggesting that the fluorescence in neurons originates from the fluorescence of the photointermediate. Our findings provide a crucial step for producing next-generation rhodopsin-based GEVIs.

Original languageEnglish
Pages (from-to)7361-7367
Number of pages7
JournalJournal of Physical Chemistry B
Volume124
Issue number34
DOIs
Publication statusPublished - Aug 27 2020

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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