Converting a light-driven proton pump into a light-gated proton channel

Keiichi Inoue, Takashi Tsukamoto, Kazumi Shimono, Yuto Suzuki, Seiji Miyauchi, Shigehiko Hayashi, Hideki Kandori, Yuki Sudo

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

There are two types of membrane-embedded ion transport machineries in nature. The ion pumps generate electrochemical potential by energy-coupled active ion transportation, while the ion channels produce action potential by stimulus-dependent passive ion transportation. About 80% of the amino acid residues of the light-driven proton pump archaerhodopsin-3 (AR3) and the light-gated cation channel channelrhodopsin (ChR) differ although they share the close similarity in architecture. Therefore, the question arises: How can these proteins function differently? The absorption maxima of ion pumps are red-shifted about 30-100 nm compared with ChRs, implying a structural difference in the retinal binding cavity. To modify the cavity, a blue-shifted AR3 named AR3-T was produced by replacing three residues located around the retinal (i.e., M128A, G132V, and A225T). AR3-T showed an inward H+ flux across the membrane, raising the possibility that it works as an inward H+ pump or an H+ channel. Electrophysiological experiments showed that the reverse membrane potential was nearly zero, indicating light-gated ion channeling activity of AR3-T. Spectroscopic characterization of AR3-T revealed similar photochemical properties to some of ChRs, including an all-trans retinal configuration, a strong hydrogen bond between the protonated retinal Schiff base and its counterion, and a slow photocycle. From these results, we concluded that the functional determinant in the H+ transporters is localized at the center of the membrane-spanning domain, but not in the cytoplasmic and extracellular domains.

Original languageEnglish
Pages (from-to)3291-3299
Number of pages9
JournalJournal of the American Chemical Society
Volume137
Issue number9
DOIs
Publication statusPublished - 2015

Fingerprint

Proton Pumps
Ion Pumps
Protons
Pumps
Ions
Membranes
Light
Schiff Bases
Ion Transport
Ion Channels
Membrane Potentials
Action Potentials
Cations
Hydrogen
Amino Acids
Hydrogen bonds
Fluxes
Proteins
Amino acids
Positive ions

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Inoue, K., Tsukamoto, T., Shimono, K., Suzuki, Y., Miyauchi, S., Hayashi, S., ... Sudo, Y. (2015). Converting a light-driven proton pump into a light-gated proton channel. Journal of the American Chemical Society, 137(9), 3291-3299. https://doi.org/10.1021/ja511788f

Converting a light-driven proton pump into a light-gated proton channel. / Inoue, Keiichi; Tsukamoto, Takashi; Shimono, Kazumi; Suzuki, Yuto; Miyauchi, Seiji; Hayashi, Shigehiko; Kandori, Hideki; Sudo, Yuki.

In: Journal of the American Chemical Society, Vol. 137, No. 9, 2015, p. 3291-3299.

Research output: Contribution to journalArticle

Inoue, K, Tsukamoto, T, Shimono, K, Suzuki, Y, Miyauchi, S, Hayashi, S, Kandori, H & Sudo, Y 2015, 'Converting a light-driven proton pump into a light-gated proton channel', Journal of the American Chemical Society, vol. 137, no. 9, pp. 3291-3299. https://doi.org/10.1021/ja511788f
Inoue K, Tsukamoto T, Shimono K, Suzuki Y, Miyauchi S, Hayashi S et al. Converting a light-driven proton pump into a light-gated proton channel. Journal of the American Chemical Society. 2015;137(9):3291-3299. https://doi.org/10.1021/ja511788f
Inoue, Keiichi ; Tsukamoto, Takashi ; Shimono, Kazumi ; Suzuki, Yuto ; Miyauchi, Seiji ; Hayashi, Shigehiko ; Kandori, Hideki ; Sudo, Yuki. / Converting a light-driven proton pump into a light-gated proton channel. In: Journal of the American Chemical Society. 2015 ; Vol. 137, No. 9. pp. 3291-3299.
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