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Ohki Y, Shinone T, Inoko S, Sudo M, Demura M, Kikukawa T, Tsukamoto T. The preferential transport of NO 3- by full-length Guillardia theta anion channelrhodopsin 1 is enhanced by its extended cytoplasmic domain. J Biol Chem 2023; 299:105305. [PMID: 37778732 PMCID: PMC10637977 DOI: 10.1016/j.jbc.2023.105305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 09/21/2023] [Accepted: 09/24/2023] [Indexed: 10/03/2023] Open
Abstract
Previous research of anion channelrhodopsins (ACRs) has been performed using cytoplasmic domain (CPD)-deleted constructs and therefore have overlooked the native functions of full-length ACRs and the potential functional role(s) of the CPD. In this study, we used the recombinant expression of full-length Guillardia theta ACR1 (GtACR1_full) for pH measurements in Pichia pastoris cell suspensions as an indirect method to assess its anion transport activity and for absorption spectroscopy and flash photolysis characterization of the purified protein. The results show that the CPD, which was predicted to be intrinsically disordered and possibly phosphorylated, enhanced NO3- transport compared to Cl- transport, which resulted in the preferential transport of NO3-. This correlated with the extended lifetime and large accumulation of the photocycle intermediate that is involved in the gate-open state. Considering that the depletion of a nitrogen source enhances the expression of GtACR1 in native algal cells, we suggest that NO3- transport could be the natural function of GtACR1_full in algal cells.
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Affiliation(s)
- Yuya Ohki
- Division of Soft Matter, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Tsukasa Shinone
- Division of Soft Matter, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Sayo Inoko
- Division of Macromolecular Functions, Department of Biological Science, School of Science, Hokkaido University, Sapporo, Japan
| | - Miu Sudo
- Division of Macromolecular Functions, Department of Biological Science, School of Science, Hokkaido University, Sapporo, Japan
| | - Makoto Demura
- Division of Soft Matter, Graduate School of Life Science, Hokkaido University, Sapporo, Japan; Division of Macromolecular Functions, Department of Biological Science, School of Science, Hokkaido University, Sapporo, Japan; Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Takashi Kikukawa
- Division of Soft Matter, Graduate School of Life Science, Hokkaido University, Sapporo, Japan; Division of Macromolecular Functions, Department of Biological Science, School of Science, Hokkaido University, Sapporo, Japan; Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Takashi Tsukamoto
- Division of Soft Matter, Graduate School of Life Science, Hokkaido University, Sapporo, Japan; Division of Macromolecular Functions, Department of Biological Science, School of Science, Hokkaido University, Sapporo, Japan; Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan.
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Preference of Proteomonas sulcata anion channelrhodopsin for NO 3- revealed using a pH electrode method. Sci Rep 2021; 11:7908. [PMID: 33846397 PMCID: PMC8041784 DOI: 10.1038/s41598-021-86812-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 03/17/2021] [Indexed: 11/13/2022] Open
Abstract
Ion channel proteins are physiologically important molecules in living organisms. Their molecular functions have been investigated using electrophysiological methods, which enable quantitative, precise and advanced measurements and thus require complex instruments and experienced operators. For simpler and easier measurements, we measured the anion transport activity of light-gated anion channelrhodopsins (ACRs) using a pH electrode method, which has already been established for ion pump rhodopsins. Using that method, we successfully measured the anion transport activity and its dependence on the wavelength of light, i.e. its action spectra, and on the anion species, i.e. its selectivity or preference, of several ACRs expressed in yeast cells. In addition, we identified the strong anion transport activity and the preference for NO3− of an ACR from a marine cryptophyte algae Proteomonas sulcata, named PsuACR_353. Such a preference was discovered for the first time in microbial pump- or channel-type rhodopsins. Nitrate is one of the most stable forms of nitrogen and is used as a nitrogen source by most organisms including plants. Therefore, PsuACR_353 may play a role in NO3− transport and might take part in NO3−-related cellular functions in nature. Measurements of a mutant protein revealed that a Thr residue in the 3rd transmembrane helix, which corresponds to Cys102 in GtACR1, contributed to the preference for NO3−. These findings will be helpful to understand the mechanisms of anion transport, selectivity and preference of PsuACR_353.
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Biophysical research in Hokkaido University, Japan. Biophys Rev 2020; 12:233-236. [PMID: 32347462 DOI: 10.1007/s12551-020-00649-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 02/11/2020] [Indexed: 10/24/2022] Open
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