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Yun JH, Park JH, Jin Z, Ohki M, Wang Y, Lupala CS, Liu H, Park SY, Lee W. Structure-Based Functional Modification Study of a Cyanobacterial Chloride Pump for Transporting Multiple Anions. J Mol Biol 2020; 432:5273-5286. [PMID: 32721401 DOI: 10.1016/j.jmb.2020.07.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 07/21/2020] [Accepted: 07/22/2020] [Indexed: 11/16/2022]
Abstract
Understanding the structure and functional mechanisms of cyanobacterial halorhodopsin has become increasingly important, given the report that Synechocystis halorhodopsin (SyHR), a homolog of the cyanobacterial halorhodopsin from Mastigocladopsis repens (MrHR), can take up divalent ions, such as SO42-, as well as chloride ions. Here, the crystal structure of MrHR, containing a unique "TSD" chloride ion conduction motif, was determined as a homotrimer at a resolution of 1.9 Å. The detailed structure of MrHR revealed a unique trimeric topology of the light-driven chloride pump, with peculiar coordination of two water molecules and hydrogen-mediated bonds near the TSD motif, as well as a short B-C loop. Structural and functional analyses of MrHR revealed key residues responsible for the anion selectivity of cyanobacterial halorhodopsin and the involvement of two chloride ion-binding sites in the ion conduction pathway. Alanine mutant of Asn63, Pro118, and Glu182 locating in the anion inlet induce multifunctional uptake of chloride, nitrate, and sulfate ions. Moreover, the structure of N63A/P118A provides information on how SyHR promotes divalent ion transport. Our findings significantly advance the structural understanding of microbial rhodopsins with different motifs. They also provide insight into the general structural framework underlying the molecular mechanisms of the cyanobacterial chloride pump containing SyHR, the only molecule known to transport both sulfate and chloride ions.
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Affiliation(s)
- Ji-Hye Yun
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea
| | - Jae-Hyun Park
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea
| | - Zeyu Jin
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea
| | - Mio Ohki
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Tsurumi, Yokohama 230-0045, Japan
| | - Yang Wang
- Complex Systems Division, Beijing Computational Science Research Center, 10 E. Xibeiwang Rd., Haidian District, Beijing 100193, China
| | - Cecylia Severin Lupala
- Complex Systems Division, Beijing Computational Science Research Center, 10 E. Xibeiwang Rd., Haidian District, Beijing 100193, China
| | - Haiguang Liu
- Complex Systems Division, Beijing Computational Science Research Center, 10 E. Xibeiwang Rd., Haidian District, Beijing 100193, China; Department of Physics, Beijing Normal University, Haidian, Beijing, 100875, China
| | - Sam-Yong Park
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Tsurumi, Yokohama 230-0045, Japan.
| | - Weontae Lee
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea.
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Besaw JE, Ou WL, Morizumi T, Eger BT, Sanchez Vasquez JD, Chu JHY, Harris A, Brown LS, Miller RJD, Ernst OP. The crystal structures of a chloride-pumping microbial rhodopsin and its proton-pumping mutant illuminate proton transfer determinants. J Biol Chem 2020; 295:14793-14804. [PMID: 32703899 DOI: 10.1074/jbc.ra120.014118] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/14/2020] [Indexed: 01/25/2023] Open
Abstract
Microbial rhodopsins are versatile and ubiquitous retinal-binding proteins that function as light-driven ion pumps, light-gated ion channels, and photosensors, with potential utility as optogenetic tools for altering membrane potential in target cells. Insights from crystal structures have been central for understanding proton, sodium, and chloride transport mechanisms of microbial rhodopsins. Two of three known groups of anion pumps, the archaeal halorhodopsins (HRs) and bacterial chloride-pumping rhodopsins, have been structurally characterized. Here we report the structure of a representative of a recently discovered third group consisting of cyanobacterial chloride and sulfate ion-pumping rhodopsins, the Mastigocladopsis repens rhodopsin (MastR). Chloride-pumping MastR contains in its ion transport pathway a unique Thr-Ser-Asp (TSD) motif, which is involved in the binding of a chloride ion. The structure reveals that the chloride-binding mode is more similar to HRs than chloride-pumping rhodopsins, but the overall structure most closely resembles bacteriorhodopsin (BR), an archaeal proton pump. The MastR structure shows a trimer arrangement reminiscent of BR-like proton pumps and shows features at the extracellular side more similar to BR than the other chloride pumps. We further solved the structure of the MastR-T74D mutant, which contains a single amino acid replacement in the TSD motif. We provide insights into why this point mutation can convert the MastR chloride pump into a proton pump but cannot in HRs. Our study points at the importance of precise coordination and exact location of the water molecule in the active center of proton pumps, which serves as a bridge for the key proton transfer.
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Affiliation(s)
- Jessica E Besaw
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Wei-Lin Ou
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Takefumi Morizumi
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Bryan T Eger
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Juan D Sanchez Vasquez
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Jessica H Y Chu
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Andrew Harris
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada
| | - Leonid S Brown
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada
| | - R J Dwayne Miller
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada; Department of Physics, University of Toronto, Toronto, Ontario, Canada
| | - Oliver P Ernst
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
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Engelhard C, Chizhov I, Siebert F, Engelhard M. Microbial Halorhodopsins: Light-Driven Chloride Pumps. Chem Rev 2018; 118:10629-10645. [DOI: 10.1021/acs.chemrev.7b00715] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
| | - Igor Chizhov
- Institute for Biophysical Chemistry, Hannover Medical School, OE8830 Carl-Neuberg-Straße 1, 30625 Hannover, Germany
| | - Friedrich Siebert
- Institut für Molekulare Medizin und Zellforschung, Sektion Biophysik, Albert-Ludwigs-Universität Freiburg, Hermann-Herderstr. 9, 79104 Freiburg, Germany
| | - Martin Engelhard
- Max Planck Institute for Molecular Physiology, Otto Hahn Str. 11, 44227 Dortmund, Germany
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Dong B, Sánchez-Magraner L, Luecke H. Structure of an Inward Proton-Transporting Anabaena Sensory Rhodopsin Mutant: Mechanistic Insights. Biophys J 2017; 111:963-72. [PMID: 27602724 DOI: 10.1016/j.bpj.2016.04.055] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/08/2016] [Accepted: 04/12/2016] [Indexed: 02/03/2023] Open
Abstract
Microbial rhodopsins are light-activated, seven-α-helical, retinylidene transmembrane proteins that have been identified in thousands of organisms across archaea, bacteria, fungi, and algae. Although they share a high degree of sequence identity and thus similarity in structure, many unique functions have been discovered and characterized among them. Some function as outward proton pumps, some as inward chloride pumps, whereas others function as light sensors or ion channels. Unique among the microbial rhodopsins characterized thus far, Anabaena sensory rhodopsin (ASR) is a photochromic sensor that interacts with a soluble 14-kDa cytoplasmic transducer that is encoded on the same operon. The sensor itself stably interconverts between all-trans-15-anti and 13-cis-15-syn retinal forms depending on the wavelength of illumination, although only the former participates in a photocycle with a signaling M intermediate. A mutation in the cytoplasmic half-channel of the protein, replacing Asp217 with Glu (D217E), results in the creation of a light-driven, single-photon, inward proton transporter. We present the 2.3 Å structure of dark-adapted D217E ASR, which reveals significant changes in the water network surrounding Glu217, as well as a shift in the carbon backbone near retinal-binding Lys210, illustrating a possible pathway leading to the protonation of Glu217 in the cytoplasmic half-channel, located 15 Å from the Schiff base. Crystallographic evidence for the protonation of nearby Glu36 is also discussed, which was described previously by Fourier transform infrared spectroscopy analysis. Finally, two histidine residues near the extracellular surface and their possible role in proton uptake are discussed.
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Affiliation(s)
- Bamboo Dong
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California
| | | | - Hartmut Luecke
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California.
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Jardón-Valadez E, Bondar AN, Tobias DJ. Electrostatic interactions and hydrogen bond dynamics in chloride pumping by halorhodopsin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1837:1964-1972. [PMID: 25256652 DOI: 10.1016/j.bbabio.2014.09.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/15/2014] [Accepted: 09/17/2014] [Indexed: 10/24/2022]
Abstract
Translocation of negatively charged ions across cell membranes by ion pumps raises the question as to how protein interactions control the location and dynamics of the ion. Here we address this question by performing extensive molecular dynamics simulations of wild type and mutant halorhodopsin, a seven-helical transmembrane protein that translocates chloride ions upon light absorption. We find that inter-helical hydrogen bonds mediated by a key arginine group largely govern the dynamics of the protein and water groups coordinating the chloride ion.
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Affiliation(s)
- Eduardo Jardón-Valadez
- Departamento de Recursos de la Tierra, Universidad Autónoma Metropolitana-Lerma, Lerma de Villada, Estado de México 52005, México
| | - Ana-Nicoleta Bondar
- Theoretical Molecular Biophysics Department of Physics, Freie University Arnimallee 14, Berlin 14195, Germany.
| | - Douglas J Tobias
- Department of Chemistry, University of California, Irvine, CA 92697-2025, USA
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Kouyama T, Kanada S, Takeguchi Y, Narusawa A, Murakami M, Ihara K. Crystal Structure of the Light-Driven Chloride Pump Halorhodopsin from Natronomonas pharaonis. J Mol Biol 2010; 396:564-79. [DOI: 10.1016/j.jmb.2009.11.061] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 11/21/2009] [Accepted: 11/24/2009] [Indexed: 10/20/2022]
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Abstract
Halorhodopsin, a light-driven halide pump, is the second archaeal rhodopsin involved in ion pumping to be studied at high resolution by X-ray crystallography. Like its cousin bacteriorhodopsin, halorhodopsin couples vectorial ion transport to the isomerisation state of a covalently linked retinal. Given the similarity and interconvertability of these two ion pumps, a unified mechanism for ion translocation by archaeal rhodopsins is now emerging.
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Affiliation(s)
- Lars-Oliver Essen
- Department of Chemistry, Philipps University, Hans-Meerwein-Strasse, D-35032 Marburg, Germany.
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Abstract
The light-activated proton-pumping bacteriorhodopsin and chloride ion-pumping halorhodopsin are compared. They belong to the family of retinal proteins, with 25% amino acid sequence homology. Both proteins have seven alpha helices across the membrane, surrounding the retinal binding pocket. Photoexcitation of all-trans retinal leads to ion transporting photocycles, which exhibit great similarities in the two proteins, despite the differences in the ion transported. The spectra of the K, L, N and O intermediates, calculated using time-resolved spectroscopic measurements, are very similar in both proteins. The absorption kinetic measurements reveal that the chloride ion transporting photocycle of halorhodopsin does not have intermediate M characteristic for deprotonated Schiff base, and intermediate L dominates the process. Energetically the photocycle of bacteriorhodopsin is driven mostly by the decrease of the entropic energy, while the photocycle of halorhodopsin is enthalpy-driven. The ion transporting steps were characterized by the electrogenicity of the intermediates, calculated from the photoinduced transient electric signal measurements. The function of both proteins could be described with the 'local access' model developed for bacteriorhodopsin. In the framework of this model it is easy to understand how bacteriorhodopsin can be converted into a chloride pump, and halorhodopsin into a proton pump, by changing the ion specificity with added ions or site-directed mutagenesis.
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Affiliation(s)
- G Váró
- Institute of Biophysics, Biological Research Center of the Hungarian Academy of Sciences, H-6701, Szeged, Hungary
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Kolbe M, Besir H, Essen LO, Oesterhelt D. Structure of the light-driven chloride pump halorhodopsin at 1.8 A resolution. Science 2000; 288:1390-6. [PMID: 10827943 DOI: 10.1126/science.288.5470.1390] [Citation(s) in RCA: 405] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Halorhodopsin, an archaeal rhodopsin ubiquitous in Haloarchaea, uses light energy to pump chloride through biological membranes. Halorhodopsin crystals were grown in a cubic lipidic phase, which allowed the x-ray structure determination of this anion pump at 1.8 angstrom resolution. Halorhodopsin assembles to trimers around a central patch consisting of palmitic acid. Next to the protonated Schiff base between Lys(242) and the isomerizable retinal chromophore, a single chloride ion occupies the transport site. Energetic calculations on chloride binding reveal a combination of ion-ion and ion-dipole interactions for stabilizing the anion 18 angstroms below the membrane surface. Ion dragging across the protonated Schiff base explains why chloride and proton translocation modes are mechanistically equivalent in archaeal rhodopsins.
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Affiliation(s)
- M Kolbe
- Department of Membrane Biochemistry, Max-Planck-Institute for Biochemistry, Am Klopferspitz 18a, D-82152 Martinsried bei München, Germany
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Abstract
In the late 1970s, on the basis of rRNA phylogeny, Archaea (archaebacteria) was identified as a distinct domain of life besides Bacteria (eubacteria) and Eucarya. Though forming a separate domain, Archaea display an enormous diversity of lifestyles and metabolic capabilities. Many archaeal species are adapted to extreme environments with respect to salinity, temperatures around the boiling point of water, and/or extremely alkaline or acidic pH. This has posed the challenge of studying the molecular and mechanistic bases on which these organisms can cope with such adverse conditions. This review considers our cumulative knowledge on archaeal mechanisms of primary energy conservation, in relationship to those of bacteria and eucarya. Although the universal principle of chemiosmotic energy conservation also holds for Archaea, distinct features have been discovered with respect to novel ion-transducing, membrane-residing protein complexes and the use of novel cofactors in bioenergetics of methanogenesis. From aerobically respiring Archaea, unusual electron-transporting supercomplexes could be isolated and functionally resolved, and a proposal on the organization of archaeal electron transport chains has been presented. The unique functions of archaeal rhodopsins as sensory systems and as proton or chloride pumps have been elucidated on the basis of recent structural information on the atomic scale. Whereas components of methanogenesis and of phototrophic energy transduction in halobacteria appear to be unique to Archaea, respiratory complexes and the ATP synthase exhibit some chimeric features with respect to their evolutionary origin. Nevertheless, archaeal ATP synthases are to be considered distinct members of this family of secondary energy transducers. A major challenge to future investigations is the development of archaeal genetic transformation systems, in order to gain access to the regulation of bioenergetic systems and to overproducers of archaeal membrane proteins as a prerequisite for their crystallization.
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Affiliation(s)
- G Schäfer
- Institut für Biochemie, Medizinische Universität zu Lübeck, Lübeck, Germany.
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