1
|
Nishikino T, Sugimoto T, Kandori H. Low-temperature FTIR spectroscopy of the L/Q switch of proteorhodopsin. Phys Chem Chem Phys 2024. [PMID: 39171479 DOI: 10.1039/d4cp02248c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
Rhodopsins are photoreceptive membrane proteins containing a retinal chromophore, and the color tuning mechanism in rhodopsins is one of the important topics. Color switch is a color-determining residue at the same position, where replacement of red- and blue-shifting amino acids in two wild-type rhodopsins causes spectral blue- and red-shifts, respectively. The first and most famous color switch in microbial rhodopsins is the L/Q switch in proteorhodopsins (PRs). Green- or blue-absorbing PR (GPR or BPR) contains Leu and Gln at position 105 of the C-helix (TM3), respectively, and their replacement converted absorbing colors. The L/Q switch enables bacteria to absorb green or blue light in shallow or deep ocean waters, respectively. Although Gln and Leu are hydrophilic and hydrophobic residues, respectively, a comprehensive mutation study of position 105 in GPR revealed that the λmax correlated with the volume of residues, not the hydropathy index. To gain structural insights into the mechanism, we applied low-temperature FTIR spectroscopy of L105Q GPR, and the obtained spectra were compared with those of GPR and BPR. The difference FTIR spectra of L105Q GPR were similar to those of BPR, not GPR, implying that the L/Q switch converts the GPR structure into a BPR structure in terms of the local environments of the retinal chromophore. It includes retinal skeletal vibration, hydrogen-bonding strength of the protonated Schiff base, amide-A vibration (peptide backbone), and protein-bound water molecules. Consequently color is switched accompanying such structural alterations, and known as the L/Q switch.
Collapse
Affiliation(s)
- Tatsuro Nishikino
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Teppei Sugimoto
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| |
Collapse
|
2
|
Nakamura T, Shinozaki Y, Otomo A, Urui T, Mizuno M, Abe-Yoshizumi R, Hashimoto M, Kojima K, Sudo Y, Kandori H, Mizutani Y. Unusual Vibrational Coupling of the Schiff Base in the Retinal Chromophore of Sodium Ion-Pumping Rhodopsins. J Phys Chem B 2024; 128:7813-7821. [PMID: 39090991 DOI: 10.1021/acs.jpcb.4c04466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
A Schiff base in the retinal chromophore of microbial rhodopsin is crucial to its ion transport mechanism. Here, we discovered an unprecedented isotope effect on the C═N stretching frequency of the Schiff base in sodium ion-pumping rhodopsins, showing an unusual interaction of the Schiff base. No amino acid residue attributable to the unprecedented isotope effect was identified, suggesting that the H-O-H bending vibration of a water molecule near the Schiff base was coupled with the C═N stretching vibration. A twist in the polyene chain in the chromophore for the sodium ion-pumping rhodopsins enabled this unusual interaction of the Schiff base. The present discovery provides new insights into the interaction network of the retinal chromophore in microbial rhodopsins.
Collapse
Affiliation(s)
- Taiki Nakamura
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yuka Shinozaki
- Department of Chemistry, School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Akihiro Otomo
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Taito Urui
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
- Department of Chemistry, School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Rei Abe-Yoshizumi
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Manami Hashimoto
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-Naka, Okayama 700-8530, Japan
| | - Keiichi Kojima
- Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-Naka, Okayama 700-8530, Japan
| | - Yuki Sudo
- Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-Naka, Okayama 700-8530, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
- Department of Chemistry, School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| |
Collapse
|
3
|
Urui T, Shionoya T, Mizuno M, Inoue K, Kandori H, Mizutani Y. Chromophore-Protein Interactions Affecting the Polyene Twist and π-π* Energy Gap of the Retinal Chromophore in Schizorhodopsins. J Phys Chem B 2024; 128:2389-2397. [PMID: 38433395 DOI: 10.1021/acs.jpcb.3c08465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
The properties of a prosthetic group are broadened by interactions with its neighboring residues in proteins. The retinal chromophore in rhodopsins absorbs light, undergoes structural changes, and drives functionally important structural changes in proteins during the photocycle. It is therefore crucial to understand how chromophore-protein interactions regulate the molecular structure and electronic state of chromophores in rhodopsins. Schizorhodopsin is a newly discovered subfamily of rhodopsins found in the genomes of Asgard archaea, which are extant prokaryotes closest to the last common ancestor of eukaryotes and of other microbial species. Here, we report the effects of a hydrogen bond between a retinal Schiff base and its counterion on the twist of the polyene chain and the color of the retinal chromophore. Correlations between spectral features revealed the unexpected fact that the twist of the polyene chain is reduced as the hydrogen bond becomes stronger, suggesting that the twist is caused by tight atomic contacts between the chromophore and nearby residues. In addition, the strength of the hydrogen bond is the primary factor affecting the color-tuning of the retinal chromophore in schizorhodopsins. The findings of this study are valuable for manipulating the molecular structure and electronic state of the chromophore by controlling chromophore-protein interactions.
Collapse
Affiliation(s)
- Taito Urui
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Tomomi Shionoya
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| |
Collapse
|
4
|
Urui T, Hayashi K, Mizuno M, Inoue K, Kandori H, Mizutani Y. Cis- Trans Reisomerization Preceding Reprotonation of the Retinal Chromophore Is Common to the Schizorhodopsin Family: A Simple and Rational Mechanism for Inward Proton Pumping. J Phys Chem B 2024; 128:744-754. [PMID: 38204413 DOI: 10.1021/acs.jpcb.3c07510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
The creation of unidirectional ion transporters across membranes represents one of the greatest challenges in chemistry. Proton-pumping rhodopsins are composed of seven transmembrane helices with a retinal chromophore bound to a lysine side chain via a Schiff base linkage and provide valuable insights for designing such transporters. What makes these transporters particularly intriguing is the discovery of both outward and inward proton-pumping rhodopsins. Surprisingly, despite sharing identical overall structures and membrane topologies, these proteins facilitate proton transport in opposite directions, implying an underlying rational mechanism that can transport protons in different directions within similar protein structures. In this study, we unraveled this mechanism by examining the chromophore structures of deprotonated intermediates in schizorhodopsins, a recently discovered subfamily of inward proton-pumping rhodopsins, using time-resolved resonance Raman spectroscopy. The photocycle of schizorhodopsins revealed the cis-trans thermal isomerization that precedes reprotonation at the Schiff base of the retinal chromophore. Notably, this order has not been observed in other proton-pumping rhodopsins, but here, it was observed in all seven schizorhodopsins studied across the archaeal domain, strongly suggesting that cis-trans thermal isomerization preceding reprotonation is a universal feature of the schizorhodopsin family. Based on these findings, we propose a structural basis for the remarkable order of events crucial for facilitating inward proton transport. The mechanism underlying inward proton transport by schizorhodopsins is straightforward and rational. The insights obtained from this study hold great promise for the design of transmembrane unidirectional ion transporters.
Collapse
Affiliation(s)
- Taito Urui
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Kouhei Hayashi
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| |
Collapse
|
5
|
Li Z, Mizuno M, Ejiri T, Hayashi S, Kandori H, Mizutani Y. Unique Vibrational Characteristics and Structures of the Photoexcited Retinal Chromophore in Ion-Pumping Rhodopsins. J Phys Chem B 2023; 127:9873-9886. [PMID: 37940604 DOI: 10.1021/acs.jpcb.3c02146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Photoisomerization of an all-trans-retinal chromophore triggers ion transport in microbial ion-pumping rhodopsins. Understanding chromophore structures in the electronically excited (S1) state provides insights into the structural evolution on the potential energy surface of the photoexcited state. In this study, we examined the structure of the S1-state chromophore in Natronomonas pharaonis halorhodopsin (NpHR), a chloride ion-pumping rhodopsin, using time-resolved resonance Raman spectroscopy. The spectral patterns of the S1-state chromophore were completely different from those of the ground-state chromophore, resulting from unique vibrational characteristics and the structure of the S1 state. Mode assignments were based on a combination of deuteration shifts of the Raman bands and hybrid quantum mechanics-molecular mechanics calculations. The present observations suggest a weakened bond alternation in the π conjugation system. A strong hydrogen-out-of-plane bending band was observed in the Raman spectra of the S1-state chromophore in NpHR, indicating a twisted polyene structure. Similar frequency shifts for the C═N/C═C and C-C stretching modes of the S1-state chromophore in NpHR were observed in the Raman spectra of sodium ion-pumping and proton-pumping rhodopsins, suggesting that these unique features are common to the S1 states of ion-pumping rhodopsins.
Collapse
Affiliation(s)
- Zixuan Li
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Osaka, Toyonaka 560-0043, Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Osaka, Toyonaka 560-0043, Japan
| | - Tomo Ejiri
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Shigehiko Hayashi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Osaka, Toyonaka 560-0043, Japan
| |
Collapse
|
6
|
Nishikawa K, Kuroiwa R, Tamogami J, Unno M, Fujisawa T. Raman Optical Activity of Retinal Chromophore in Sensory Rhodopsin II. J Phys Chem B 2023; 127:7244-7250. [PMID: 37556781 DOI: 10.1021/acs.jpcb.3c02391] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
Raman optical activity (ROA) spectroscopy was used to study the conformation of the retinal chromophore in sensory rhodopsin II (SRII), which is a blue-green light sensor of microbes. The ROA spectrum consisted of the negative vibrational bands of the chromophore, whose relative intensities are similar to those of the parent Raman spectrum. This spectral feature was explained by the left-handed helical twist of the retinal chromophore on the basis of quantum chemical calculations. On the other hand, we found that the chromophore conformation based on the crystal structures of SRII has a right-handed helical twist, which does not agree with the observation. This specific result suggests that the consistency with chiro-optical properties can be a key criterion for the accurate prediction and/or evaluation of chromophore conformation in retinal-binding proteins.
Collapse
Affiliation(s)
- Kouhei Nishikawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Ryosuke Kuroiwa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Jun Tamogami
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
| | - Masashi Unno
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Tomotsumi Fujisawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| |
Collapse
|
7
|
Shibata K, Oda K, Nishizawa T, Hazama Y, Ono R, Takaramoto S, Bagherzadeh R, Yawo H, Nureki O, Inoue K, Akiyama H. Twisting and Protonation of Retinal Chromophore Regulate Channel Gating of Channelrhodopsin C1C2. J Am Chem Soc 2023; 145:10779-10789. [PMID: 37129501 DOI: 10.1021/jacs.3c01879] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Channelrhodopsins (ChRs) are light-gated ion channels and central optogenetic tools that can control neuronal activity with high temporal resolution at the single-cell level. Although their application in optogenetics has rapidly progressed, it is unsolved how their channels open and close. ChRs transport ions through a series of interlocking elementary processes that occur over a broad time scale of subpicoseconds to seconds. During these processes, the retinal chromophore functions as a channel regulatory domain and transfers the optical input as local structural changes to the channel operating domain, the helices, leading to channel gating. Thus, the core question on channel gating dynamics is how the retinal chromophore structure changes throughout the photocycle and what rate-limits the kinetics. Here, we investigated the structural changes in the retinal chromophore of canonical ChR, C1C2, in all photointermediates using time-resolved resonance Raman spectroscopy. Moreover, to reveal the rate-limiting factors of the photocycle and channel gating, we measured the kinetic isotope effect of all photoreaction processes using laser flash photolysis and laser patch clamp, respectively. Spectroscopic and electrophysiological results provided the following understanding of the channel gating: the retinal chromophore highly twists upon the retinal Schiff base (RSB) deprotonation, causing the surrounding helices to move and open the channel. The ion-conducting pathway includes the RSB, where inflowing water mediates the proton to the deprotonated RSB. The twisting of the retinal chromophore relaxes upon the RSB reprotonation, which closes the channel. The RSB reprotonation rate-limits the channel closing.
Collapse
Affiliation(s)
- Keisei Shibata
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Kazumasa Oda
- Department of Biological Sciences Graduate School of Science, The University of Tokyo, Tokyo 113-0034, Japan
| | - Tomohiro Nishizawa
- Department of Biological Sciences Graduate School of Science, The University of Tokyo, Tokyo 113-0034, Japan
| | - Yuji Hazama
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Ryohei Ono
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
- Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan
| | - Shunki Takaramoto
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Reza Bagherzadeh
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Hiromu Yawo
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Osamu Nureki
- Department of Biological Sciences Graduate School of Science, The University of Tokyo, Tokyo 113-0034, Japan
| | - Keiichi Inoue
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Hidefumi Akiyama
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| |
Collapse
|
8
|
Urui T, Das I, Mizuno M, Sheves M, Mizutani Y. Origin of a Double-Band Feature in the Ethylenic C═C Stretching Modes of the Retinal Chromophore in Heliorhodopsins. J Phys Chem B 2022; 126:8680-8688. [PMID: 36281583 DOI: 10.1021/acs.jpcb.2c04883] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Photoreceptor proteins play a critical role in light utilization for energy conversion and environmental sensing. Rhodopsin is a prototypical photoreceptor protein containing a retinal group that functions as a light-receptive site. It is essential to characterize the structure of the retinal chromophore because the chromophore structure, along with retinal-protein interactions, regulates which wavelengths of light are absorbed. Resonance Raman spectroscopy is a powerful tool to characterize chromophore structures in proteins. The resonance Raman spectra of heliorhodopsins, a recently discovered rhodopsin family, were previously reported to exhibit two intense ethylenic C═C stretching bands never observed for type-1 rhodopsins. Here, we show that the double-band feature in the ethylenic C═C stretching modes is not due to structural inhomogeneity but rather to the retinal polyene chain's linear structure. It contrasts with bent all-trans chromophore in type-1 rhodopsins. The linear structure of the chromophore results from weak atomic contacts between the 13-methyl group and a nearby Trp side chain, which can slow thermal reisomerization in the photocycle. It is possible that the deceleration of reisomerization increases the lifetime of the signaling intermediate for photosensory function.
Collapse
Affiliation(s)
- Taito Urui
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043, Osaka, Japan
| | - Ishita Das
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 76305, Israel
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043, Osaka, Japan
| | - Mordechai Sheves
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 76305, Israel
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043, Osaka, Japan
| |
Collapse
|
9
|
Church JR, Amoyal GS, Borin VA, Adam S, Olsen JMH, Schapiro I. Deciphering the Spectral Tuning Mechanism in Proteorhodopsin: The Dominant Role of Electrostatics Instead of Chromophore Geometry. Chemistry 2022; 28:e202200139. [PMID: 35307890 PMCID: PMC9325082 DOI: 10.1002/chem.202200139] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Indexed: 11/11/2022]
Abstract
Proteorhodopsin (PR) is a photoactive proton pump found in marine bacteria. There are two phenotypes of PR exhibiting an environmental adaptation to the ocean's depth which tunes their maximum absorption: blue‐absorbing proteorhodopsin (BPR) and green‐absorbing proteorhodopsin (GPR). This blue/green color‐shift is controlled by a glutamine to leucine substitution at position 105 which accounts for a 20 nm shift. Typically, spectral tuning in rhodopsins is rationalized by the external point charge model but the Q105L mutation is charge neutral. To study this tuning mechanism, we employed the hybrid QM/MM method with sampling from molecular dynamics. Our results reveal that the positive partial charge of glutamine near the C14−C15 bond of retinal shortens the effective conjugation length of the chromophore compared to the leucine residue. The derived mechanism can be applied to explain the color regulation in other retinal proteins and can serve as a guideline for rational design of spectral shifts.
Collapse
Affiliation(s)
- Jonathan R Church
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
| | - Gil S Amoyal
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
| | - Veniamin A Borin
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
| | - Suliman Adam
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
| | | | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
| |
Collapse
|
10
|
Shionoya T, Singh M, Mizuno M, Kandori H, Mizutani Y. Strongly Hydrogen-Bonded Schiff Base and Adjoining Polyene Twisting in the Retinal Chromophore of Schizorhodopsins. Biochemistry 2021; 60:3050-3057. [PMID: 34601881 DOI: 10.1021/acs.biochem.1c00529] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A transmembrane proton gradient is generated and maintained by proton pumps in a cell. Metagenomics studies have recently identified a new category of rhodopsin intermediates between type-1 rhodopsins and heliorhodopsins, named schizorhodopsins (SzRs). SzRs are light-driven inward proton pumps. Comprehensive resonance Raman measurements were conducted to characterize the structure of the retinal chromophore in the unphotolyzed state of four SzRs. The spectra of all four SzRs show that the retinal chromophore is in the all-trans and 15-anti configuration and that the Schiff base is protonated. The polyene chain is planar in the center of the retinal chromophore and is twisted in the vicinity of the protonated Schiff base. The protonated Schiff base in the SzRs forms a stronger hydrogen bond than that in outward proton-pumping rhodopsins. We determined that the hydrogen-bonding partner of the protonated Schiff base is not a water molecule but an amino acid residue, presumably an Asp residue in helix G. The present observations provide valuable insights into the inward proton-pumping mechanism of SzRs.
Collapse
Affiliation(s)
- Tomomi Shionoya
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Manish Singh
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| |
Collapse
|
11
|
Fujisawa T, Nishikawa K, Tamogami J, Unno M. Conformational Analysis of a Retinal Schiff Base Chromophore in Proteorhodopsin by Raman Optical Activity. J Phys Chem Lett 2021; 12:9564-9568. [PMID: 34581580 DOI: 10.1021/acs.jpclett.1c02552] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Raman optical activity (ROA) spectroscopy was used to study the conformation of the retinal Schiff base chromophore in green-light-absorbing proteorhodopsin, which is a globally distributed light-driven proton pump of aquatic bacteria. The ROA spectrum consisted mostly of the negative vibrational bands of the chromophore, while the hydrogen out-of-plane mode (at 960 cm-1) appeared as the sole positive band. This distinct spectral feature was not explained by the twisted structure of the retinal Schiff base but was reproduced by the structural model in which the polyene chain on the β-ionone ring side was bent out-of-plane. The bent chromophore structure potentially couples with proton pumping through the motion of the sixth helix in contact with the β-ionone ring.
Collapse
Affiliation(s)
- Tomotsumi Fujisawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Kouhei Nishikawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Jun Tamogami
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
| | - Masashi Unno
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| |
Collapse
|
12
|
Urui T, Mizuno M, Otomo A, Kandori H, Mizutani Y. Resonance Raman Determination of Chromophore Structures of Heliorhodopsin Photointermediates. J Phys Chem B 2021; 125:7155-7162. [PMID: 34167296 DOI: 10.1021/acs.jpcb.1c04010] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Light is utilized as energy or information by rhodopsins (membrane proteins that contain a retinal chromophore). Heliorhodopsins (HeRs) are a new class of rhodopsins with low sequence identity (<15%) to microbial and animal rhodopsins. Their physiological roles remain unknown, although the involvement of a long-lived intermediate in the photocycle suggests a light-sensor function. Characterization of the molecular structures of the intermediates is essential to an understanding of the roles and mechanisms of HeRs. We determined the chromophore structures of the intermediates in HeR 48C12 by time-resolved resonance Raman spectroscopy and observed that the hydrogen bond of the protonated Schiff base strengthened prior to deprotonation. The chromophore is photoisomerized from the all-trans to the 13-cis form and is reisomerized in the transition from the O intermediate to the unphotolyzed state. Our results demonstrate that the chromophore structure evolves similarly to microbial rhodopsins, despite the dissimilarity in amino acid residues surrounding the chromophore.
Collapse
Affiliation(s)
- Taito Urui
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Akihiro Otomo
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| |
Collapse
|
13
|
Abstract
This is a review of relevant Raman spectroscopy (RS) techniques and their use in structural biology, biophysics, cells, and tissues imaging towards development of various medical diagnostic tools, drug design, and other medical applications. Classical and contemporary structural studies of different water-soluble and membrane proteins, DNA, RNA, and their interactions and behavior in different systems were analyzed in terms of applicability of RS techniques and their complementarity to other corresponding methods. We show that RS is a powerful method that links the fundamental structural biology and its medical applications in cancer, cardiovascular, neurodegenerative, atherosclerotic, and other diseases. In particular, the key roles of RS in modern technologies of structure-based drug design are the detection and imaging of membrane protein microcrystals with the help of coherent anti-Stokes Raman scattering (CARS), which would help to further the development of protein structural crystallography and would result in a number of novel high-resolution structures of membrane proteins—drug targets; and, structural studies of photoactive membrane proteins (rhodopsins, photoreceptors, etc.) for the development of new optogenetic tools. Physical background and biomedical applications of spontaneous, stimulated, resonant, and surface- and tip-enhanced RS are also discussed. All of these techniques have been extensively developed during recent several decades. A number of interesting applications of CARS, resonant, and surface-enhanced Raman spectroscopy methods are also discussed.
Collapse
|
14
|
Han S, Kim SH, Cho JC, Song J, Bleckner G, Jung KH. Photochemical characterization of flavobacterial rhodopsin: The importance of the helix E region for heat stability. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148092. [PMID: 31669491 DOI: 10.1016/j.bbabio.2019.148092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/26/2019] [Accepted: 10/18/2019] [Indexed: 11/19/2022]
Abstract
Although many microbial rhodopsins have been discovered many of organisms in a variety of habitats, little is known about the property and diversity of rhodopsin in flavobacteria. Recent studies discovered that many proteorhodopsin (PR)-like proteins exist in genomes of flavobacteria. Following the isolation of a flavobacterial rhodopsins (FR) from the flavobacteria IMCC1997 from the East Sea of Korea, we characterized its photochemical features. We confirmed that the FR expression is induced by light in the IMCC1997 cell. Upon receiving light energy in vitro, the proton acceptor (D83) and donor (E94) of the FR translocate protons from intracellular to extracellular regions. Compared with proteorhodopsin (PR), the FR from IMCC 1997 cells is very unstable, which may be explained by their primary sequence differences. The ratio of all trans/13-cis retinal conformation does not influence this stability. To measure the stability of FR, we tested heat endurance at 70 °C and found that the heat endurance time of some FR mutants increased. Based upon these results, we found the helix E of this protein to be critical for the unstability of FR.
Collapse
Affiliation(s)
- SongI Han
- Dept. of Bioengineering, Rice University, Houston, TX 77005, USA
| | - Se-Hwan Kim
- Dept. of Life Science and Institute of Biological Interfaces, Sogang University, Seoul 04107, Republic of Korea
| | - Jang-Chon Cho
- Dept. of Biological Sciences, Inha University, Incheon 22212, Republic of Korea
| | - Jaeho Song
- Dept. of Biological Sciences, Inha University, Incheon 22212, Republic of Korea
| | - Gwen Bleckner
- Princeton international school of mathematics and science, Princeton, NJ 08540, USA
| | - Kwang-Hwan Jung
- Dept. of Life Science and Institute of Biological Interfaces, Sogang University, Seoul 04107, Republic of Korea.
| |
Collapse
|
15
|
Mei G, Mamaeva N, Ganapathy S, Wang P, DeGrip WJ, Rothschild KJ. Analog Retinal Redshifts Visible Absorption of QuasAr Transmembrane Voltage Sensors into Near-infrared. Photochem Photobiol 2019; 96:55-66. [PMID: 31556123 PMCID: PMC7004139 DOI: 10.1111/php.13169] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 09/05/2019] [Accepted: 09/07/2019] [Indexed: 12/01/2022]
Abstract
Opsin‐based transmembrane voltage sensors (OTVSs) are increasingly important tools for neuroscience enabling neural function in complex brain circuits to be explored in live, behaving animals. However, the visible wavelengths required for fluorescence excitation of the current generation of OTVSs limit optogenetic imaging in the brain to depths of only a few mm due to the strong absorption and scattering of visible light by biological tissues. We report that substitution of the native A1 retinal chromophore of the widely used QuasAr1/2 OTVSs with the retinal analog MMAR containing a methylamino‐modified dimethylphenyl ring results in over a 100‐nm redshift of the maxima of the absorption and fluorescence emission bands to near 700 and 840 nm, respectively. FT‐Raman spectroscopy reveals that at pH 7 QuasAr1 with both the A1 and MMAR chromophores possess predominantly an all‐trans protonated Schiff base configuration with the MMAR chromophore exhibiting increased torsion of the polyene single‐/double‐bond system similar to the O‐intermediate of the BR photocycle. In contrast, the A1 and the MMAR chromophores of QuasAr2 exist partially in a 13‐cis PSB configuration. These results demonstrate that QuasArs containing the MMAR chromophore are attractive candidates for use as NIR‐OTVSs, especially for applications such as deep brain imaging.
Collapse
Affiliation(s)
- Gaoxiang Mei
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, MA
| | - Natalia Mamaeva
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, MA
| | - Srividya Ganapathy
- Department of Biophysical Organic Chemistry, Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | | | - Willem J DeGrip
- Department of Biophysical Organic Chemistry, Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands.,Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kenneth J Rothschild
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, MA
| |
Collapse
|
16
|
Mizuno M, Shimoo Y, Kandori H, Mizutani Y. Effect of a bound anion on the structure and dynamics of halorhodopsin from Natronomonas pharaonis. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:054703. [PMID: 31673569 PMCID: PMC6811361 DOI: 10.1063/1.5125621] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Accepted: 10/09/2019] [Indexed: 06/10/2023]
Abstract
Active ion transport across membranes is vital to maintaining the electrochemical gradients of ions in cells and is mediated by transmembrane proteins. Halorhodopsin (HR) functions as a light-driven inward pump for chloride ions. The protein contains all-trans-retinal bound to a specific lysine residue through a protonated Schiff base. Interaction between the bound chloride ion and the protonated Schiff base is crucial for ion transport because chloride ion movement is driven by the flipping of the protonated Schiff base upon photoisomerization. However, it remains unknown how this interaction evolves in the HR photocycle. Here, we addressed the effect of the bound anion on the structure and dynamics of HR from Natronomonas pharaonis in the early stage of the photocycle. Comparison of the chloride-bound, formate-bound, and anion-depleted forms provided insights into the interaction between the bound anion and the chromophore/protein moiety. In the unphotolyzed state, the bound anion affects the π-conjugation of the polyene chain and the hydrogen bond of the protonated Schiff base of the retinal chromophore. Picosecond time scale measurements showed that the band intensities of the W16 and W18 modes of the tryptophan residues decreased instantaneously upon photoexcitation of the formate-bound form. In contrast, these intensity decreases were delayed for the chloride-bound and anion-depleted forms. These observations suggest the stronger interactions of the bound formate ion with the retinal chromophore and the chromophore pocket. On the nanosecond to microsecond timescales, we found that the interaction between the protonated Schiff base and the bound ion is broken upon formation of the K intermediate and is recovered following translocation of the bound anion toward the protonated Schiff base in the L intermediate. Our results demonstrate that the hydrogen-bonding ability of the bound anion plays an essential role in the ion transport of light-driven anion pumps.
Collapse
Affiliation(s)
- Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yumi Shimoo
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| |
Collapse
|
17
|
Nishimura N, Mizuno M, Kandori H, Mizutani Y. Distortion and a Strong Hydrogen Bond in the Retinal Chromophore Enable Sodium-Ion Transport by the Sodium-Ion Pump KR2. J Phys Chem B 2019; 123:3430-3440. [DOI: 10.1021/acs.jpcb.9b00928] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nao Nishimura
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| |
Collapse
|
18
|
Mei G, Mamaeva N, Ganapathy S, Wang P, DeGrip WJ, Rothschild KJ. Raman spectroscopy of a near infrared absorbing proteorhodopsin: Similarities to the bacteriorhodopsin O photointermediate. PLoS One 2018; 13:e0209506. [PMID: 30586409 PMCID: PMC6306260 DOI: 10.1371/journal.pone.0209506] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 12/06/2018] [Indexed: 02/07/2023] Open
Abstract
Microbial rhodopsins have become an important tool in the field of optogenetics. However, effective in vivo optogenetics is in many cases severely limited due to the strong absorption and scattering of visible light by biological tissues. Recently, a combination of opsin site-directed mutagenesis and analog retinal substitution has produced variants of proteorhodopsin which absorb maximally in the near-infrared (NIR). In this study, UV-Visible-NIR absorption and resonance Raman spectroscopy were used to study the double mutant, D212N/F234S, of green absorbing proteorhodopsin (GPR) regenerated with MMAR, a retinal analog containing a methylamino modified β-ionone ring. Four distinct subcomponent absorption bands with peak maxima near 560, 620, 710 and 780 nm are detected with the NIR bands dominant at pH <7.3, and the visible bands dominant at pH 9.5. FT-Raman using 1064-nm excitation reveal two strong ethylenic bands at 1482 and 1498 cm-1 corresponding to the NIR subcomponent absorption bands based on an extended linear correlation between λmax and γC = C. This spectrum exhibits two intense bands in the fingerprint and HOOP mode regions that are highly characteristic of the O640 photointermediate from the light-adapted bacteriorhodopsin photocycle. In contrast, 532-nm excitation enhances the 560-nm component, which exhibits bands very similar to light-adapted bacteriorhodopsin and/or the acid-purple form of bacteriorhodopsin. Native GPR and its mutant D97N when regenerated with MMAR also exhibit similar absorption and Raman bands but with weaker contributions from the NIR absorbing components. Based on these results it is proposed that the NIR absorption in GPR-D212N/F234S with MMAR arises from an O-like chromophore, where the Schiff base counterion D97 is protonated and the MMAR adopts an all-trans configuration with a non-planar geometry due to twists in the conjugated polyene segment. This configuration is characterized by extensive charge delocalization, most likely involving nitrogens atoms in the MMAR chromophore.
Collapse
Affiliation(s)
- Gaoxiang Mei
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, Massachusetts, United States of America
| | - Natalia Mamaeva
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, Massachusetts, United States of America
| | - Srividya Ganapathy
- Department of Biophysical Organic Chemistry, Leiden Institute of Chemistry, Leiden UniversityAR Leiden, The Netherlands
| | - Peng Wang
- Bruker Corporation, Billerica, MA, United States of America
| | - Willem J. DeGrip
- Department of Biophysical Organic Chemistry, Leiden Institute of Chemistry, Leiden UniversityAR Leiden, The Netherlands
| | - Kenneth J. Rothschild
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
19
|
Otomo A, Mizuno M, Singh M, Shihoya W, Inoue K, Nureki O, Béjà O, Kandori H, Mizutani Y. Resonance Raman Investigation of the Chromophore Structure of Heliorhodopsins. J Phys Chem Lett 2018; 9:6431-6436. [PMID: 30351947 DOI: 10.1021/acs.jpclett.8b02741] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Heliorhodopsins (HeRs) are a new category of retinal-bound proteins recently discovered through functional metagenomics analysis that exhibit obvious differences from type-1 microbial rhodopsins. We conducted the first detailed structural characterization of the retinal chromophore in HeRs using resonance Raman spectroscopy. The observed spectra clearly show that the Schiff base of the chromophore is protonated and forms a strong hydrogen bond to a species other than a water molecule, highly likely a counterion residue. The vibrational mode of the Schiff base of HeRs exhibits similarities with that of photosensory microbial rhodopsins, that is consistent with the previous proposal that HeRs function as photosensors. We also revealed unusual spectral features of the in-plane chain vibrations of the chromophore, suggesting an unprecedented geometry of the Schiff base caused by a difference in the retinal pocket structure of HeRs. These data demonstrate structural characteristics of the photoreceptive site in this novel type of rhodopsin family.
Collapse
Affiliation(s)
- Akihiro Otomo
- Department of Chemistry , Graduate School of Science, Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Misao Mizuno
- Department of Chemistry , Graduate School of Science, Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Manish Singh
- Department of Life Science and Applied Chemistry , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan
| | - Wataru Shihoya
- Department of Biological Sciences , Graduate School of Science, The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-0032 , Japan
| | - Keiichi Inoue
- Department of Life Science and Applied Chemistry , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan
- OptoBioTechnology Research Center , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan
- The Institute for Solid State Physics , The University of Tokyo , Kashiwa 277-8581 , Japan
| | - Osamu Nureki
- Department of Biological Sciences , Graduate School of Science, The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-0032 , Japan
| | - Oded Béjà
- Faculty of Biology , Technion Israel Institute of Technology , Haifa 32000 , Israel
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan
- OptoBioTechnology Research Center , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan
| | - Yasuhisa Mizutani
- Department of Chemistry , Graduate School of Science, Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| |
Collapse
|
20
|
Fujisawa T, Abe M, Tamogami J, Kikukawa T, Kamo N, Unno M. Low-temperature Raman spectroscopy reveals small chromophore distortion in primary photointermediate of proteorhodopsin. FEBS Lett 2018; 592:3054-3061. [PMID: 30098005 DOI: 10.1002/1873-3468.13219] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/29/2018] [Accepted: 08/03/2018] [Indexed: 11/07/2022]
Abstract
Proteorhodopsin (PR) is a microbial rhodopsin functioning as a light-driven proton pump in aquatic bacteria. We performed low-temperature Raman measurements of PR to obtain the structure of the primary photoproduct, the K intermediate (PRK ). PRK showed the hydrogen-out-of-plane modes that are much less intense than those of bacteriorhodopsin as the prototypical light-driven proton pump from haloarchaea. The present results reveal the significantly relaxed chromophore structure in PRK , which can be coupled to the slow kinetics of the K intermediate. This structure suggests that PR transports protons using the small energy storage within the chromophore at the start of its photocycle.
Collapse
Affiliation(s)
- Tomotsumi Fujisawa
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University, Japan
| | - Masahiro Abe
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University, Japan
| | - Jun Tamogami
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime, Japan
| | - Takashi Kikukawa
- Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan.,Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Naoki Kamo
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime, Japan
| | - Masashi Unno
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University, Japan
| |
Collapse
|
21
|
Shionoya T, Mizuno M, Tsukamoto T, Ikeda K, Seki H, Kojima K, Shibata M, Kawamura I, Sudo Y, Mizutani Y. High Thermal Stability of Oligomeric Assemblies of Thermophilic Rhodopsin in a Lipid Environment. J Phys Chem B 2018; 122:6945-6953. [PMID: 29893559 DOI: 10.1021/acs.jpcb.8b04894] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Thermophilic rhodopsin (TR) is a light-driven proton pump from the extreme thermophile Thermus thermophilus JL-18. Previous studies on TR solubilized with detergent showed that the protein exhibits high thermal stability and forms a trimer at room temperature but irreversibly dissociates into monomers when incubated at physiological temperature (75 °C). In the present study, we used resonance Raman (RR) spectroscopy, solid-state NMR spectroscopy, and high-speed atomic force microscopy to analyze the oligomeric structure of TR in a lipid environment. The obtained spectra and microscopic images demonstrate that TR adopts a pentameric form in a lipid environment and that this assembly is stable at the physiological temperature, in contrast to the behavior of the protein in the solubilized state. These results indicate that the thermal stability of the oligomeric assembly of TR is higher in a lipid environment than in detergent micelles. The observed RR spectra also showed that the retinal chromophore is strongly hydrogen bonded to an internal water molecule via a protonated Schiff base, which is characteristic of proton-pumping rhodopsins. The obtained data strongly suggest that TR functions in the pentameric form at physiological temperature in the extreme thermophile T. thermophilus JL-18. We utilized the high thermal stability of the monomeric form of solubilized TR and here report the first RR spectra of the monomeric form of a microbial rhodopsin. The observed RR spectra revealed that the monomerization of TR alters the chromophore structure: there are changes in the bond alternation of the polyene chain and in the hydrogen-bond strength of the protonated Schiff base. The present study revealed the high thermal stability of oligomeric assemblies of TR in the lipid environment and suggested the importance of using TR embedded in lipid membrane for elucidation of its functional mechanism.
Collapse
Affiliation(s)
- Tomomi Shionoya
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Takashi Tsukamoto
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama University , 1-1-1 Tsushima-naka , Kita-ku, Okayama 700-8530 , Japan
| | | | - Hayato Seki
- Graduate School of Engineering , Yokohama National University , Hodogaya-ku, Yokohama 240-8501 , Japan
| | - Keiichi Kojima
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama University , 1-1-1 Tsushima-naka , Kita-ku, Okayama 700-8530 , Japan
| | | | - Izuru Kawamura
- Graduate School of Engineering , Yokohama National University , Hodogaya-ku, Yokohama 240-8501 , Japan
| | - Yuki Sudo
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama University , 1-1-1 Tsushima-naka , Kita-ku, Okayama 700-8530 , Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| |
Collapse
|
22
|
Mizuno M, Nakajima A, Kandori H, Mizutani Y. Structural Evolution of a Retinal Chromophore in the Photocycle of Halorhodopsin from Natronobacterium pharaonis. J Phys Chem A 2018; 122:2411-2423. [DOI: 10.1021/acs.jpca.7b12332] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and
| | - Ayumi Nakajima
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and
| | - Hideki Kandori
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and
| |
Collapse
|
23
|
Buda F, Keijer T, Ganapathy S, de Grip WJ. A Quantum-mechanical Study of the Binding Pocket of Proteorhodopsin: Absorption and Vibrational Spectra Modulated by Analogue Chromophores. Photochem Photobiol 2017; 93:1399-1406. [DOI: 10.1111/php.12800] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 05/22/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Francesco Buda
- Leiden University; Leiden Institute of Chemistry; Leiden The Netherlands
| | - Tom Keijer
- Leiden University; Leiden Institute of Chemistry; Leiden The Netherlands
| | - Srividya Ganapathy
- Leiden University; Leiden Institute of Chemistry; Leiden The Netherlands
| | - Willem J. de Grip
- Leiden University; Leiden Institute of Chemistry; Leiden The Netherlands
- Radboud University Medical Center; Radboud Institute for Molecular Life Sciences; Nijmegen The Netherlands
| |
Collapse
|
24
|
Yi A, Li H, Mamaeva N, Fernandez De Cordoba RE, Lugtenburg J, DeGrip WJ, Spudich JL, Rothschild KJ. Structural Changes in an Anion Channelrhodopsin: Formation of the K and L Intermediates at 80 K. Biochemistry 2017; 56:2197-2208. [PMID: 28350445 DOI: 10.1021/acs.biochem.7b00002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A recently discovered natural family of light-gated anion channelrhodopsins (ACRs) from cryptophyte algae provides an effective means of optogenetically silencing neurons. The most extensively studied ACR is from Guillardia theta (GtACR1). Earlier studies of GtACR1 have established a correlation between formation of a blue-shifted L-like intermediate and the anion channel "open" state. To study structural changes of GtACR1 in the K and L intermediates of the photocycle, a combination of low-temperature Fourier transform infrared (FTIR) and ultraviolet-visible absorption difference spectroscopy was used along with stable-isotope retinal labeling and site-directed mutagenesis. In contrast to bacteriorhodopsin (BR) and other microbial rhodopsins, which form only a stable red-shifted K intermediate at 80 K, GtACR1 forms both stable K and L-like intermediates. Evidence includes the appearance of positive ethylenic and fingerprint vibrational bands characteristic of the L intermediate as well as a positive visible absorption band near 485 nm. FTIR difference bands in the carboxylic acid C═O stretching region indicate that several Asp/Glu residues undergo hydrogen bonding changes at 80 K. The Glu68 → Gln and Ser97 → Glu substitutions, residues located close to the retinylidene Schiff base, altered the K:L ratio and several of the FTIR bands in the carboxylic acid region. In the case of the Ser97 → Glu substitution, a significant red-shift of the absorption wavelength of the K and L intermediates occurs. Sequence comparisons suggest that L formation in GtACR1 at 80 K is due in part to the substitution of the highly conserved Leu or Ile at position 93 in helix 3 (BR sequence) with the homologous Met105 in GtACR1.
Collapse
Affiliation(s)
- Adrian Yi
- Molecular Biophysics Laboratory, Photonics Center, and Department of Physics, Boston University , Boston, Massachusetts 02215, United States
| | - Hai Li
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, McGovern Medical School , Houston, Texas 77030, United States
| | - Natalia Mamaeva
- Molecular Biophysics Laboratory, Photonics Center, and Department of Physics, Boston University , Boston, Massachusetts 02215, United States
| | - Roberto E Fernandez De Cordoba
- Molecular Biophysics Laboratory, Photonics Center, and Department of Physics, Boston University , Boston, Massachusetts 02215, United States
| | - Johan Lugtenburg
- Department of Biophysical Organic Chemistry, Leiden Institute of Chemistry, Leiden University , 2300 AR Leiden, The Netherlands
| | - Willem J DeGrip
- Department of Biophysical Organic Chemistry, Leiden Institute of Chemistry, Leiden University , 2300 AR Leiden, The Netherlands
| | - John L Spudich
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, McGovern Medical School , Houston, Texas 77030, United States
| | - Kenneth J Rothschild
- Molecular Biophysics Laboratory, Photonics Center, and Department of Physics, Boston University , Boston, Massachusetts 02215, United States
| |
Collapse
|
25
|
Niho A, Yoshizawa S, Tsukamoto T, Kurihara M, Tahara S, Nakajima Y, Mizuno M, Kuramochi H, Tahara T, Mizutani Y, Sudo Y. Demonstration of a Light-Driven SO42– Transporter and Its Spectroscopic Characteristics. J Am Chem Soc 2017; 139:4376-4389. [DOI: 10.1021/jacs.6b12139] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Akiko Niho
- Faculty
of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Susumu Yoshizawa
- Atmosphere
and Ocean Research Institute, The University of Tokyo, Chiba 277-8564, Japan
| | - Takashi Tsukamoto
- Faculty
of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Marie Kurihara
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Shinya Tahara
- Molecular
Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | - Yu Nakajima
- Atmosphere
and Ocean Research Institute, The University of Tokyo, Chiba 277-8564, Japan
| | - Misao Mizuno
- Department
of Chemistry, Graduate School of Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hikaru Kuramochi
- Molecular
Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
- Ultrafast
Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako 351-0198, Japan
| | - Tahei Tahara
- Molecular
Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
- Ultrafast
Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako 351-0198, Japan
| | - Yasuhisa Mizutani
- Department
of Chemistry, Graduate School of Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yuki Sudo
- Faculty
of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| |
Collapse
|
26
|
Yi A, Mamaeva N, Li H, Spudich JL, Rothschild KJ. Resonance Raman Study of an Anion Channelrhodopsin: Effects of Mutations near the Retinylidene Schiff Base. Biochemistry 2016; 55:2371-80. [PMID: 27039989 DOI: 10.1021/acs.biochem.6b00104] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Optogenetics relies on the expression of specific microbial rhodopsins in the neuronal plasma membrane. Most notably, this includes channelrhodopsins, which when heterologously expressed in neurons function as light-gated cation channels. Recently, a new class of microbial rhodopsins, termed anion channel rhodopsins (ACRs), has been discovered. These proteins function as efficient light-activated channels strictly selective for anions. They exclude the flow of protons and other cations and cause hyperpolarization of the membrane potential in neurons by allowing the inward flow of chloride ions. In this study, confocal near-infrared resonance Raman spectroscopy (RRS) along with hydrogen/deuterium exchange, retinal analogue substitution, and site-directed mutagenesis were used to study the retinal structure as well as its interactions with the protein in the unphotolyzed state of an ACR from Guillardia theta (GtACR1). These measurements reveal that (i) the retinal chromophore exists as an all-trans configuration with a protonated Schiff base (PSB) very similar to that of bacteriorhodopsin (BR), (ii) the chromophore RRS spectrum is insensitive to changes in pH from 3 to 11, whereas above this pH the Schiff base (SB) is deprotonated, (iii) when Ser97, the homologue to Asp85 in BR, is replaced with a Glu, it remains in a neutral form (i.e., as a carboxylic acid) but is deprotonated at higher pH to form a blue-shifted species, (iv) Asp234, the homologue of the protonated retinylidene SB counterion Asp212 in BR, does not serve as the primary counteranion for the protonated SB, and (v) substitution of Glu68 with an Gln increases the pH at which SB deprotonation is observed. These results suggest that Glu68 and Asp234 located near the SB exist in a neutral state in unphotolyzed GtACR1 and indicate that other unidentified negative charges stabilize the protonated state of the GtACR1 SB.
Collapse
Affiliation(s)
- Adrian Yi
- Molecular Biophysics Laboratory, Photonics Center, and Department of Physics, Boston University , Boston, Massachusetts 02215, United States
| | - Natalia Mamaeva
- Molecular Biophysics Laboratory, Photonics Center, and Department of Physics, Boston University , Boston, Massachusetts 02215, United States
| | - Hai Li
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, McGovern Medical School , Houston, Texas 77030, United States
| | - John L Spudich
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, McGovern Medical School , Houston, Texas 77030, United States
| | - Kenneth J Rothschild
- Molecular Biophysics Laboratory, Photonics Center, and Department of Physics, Boston University , Boston, Massachusetts 02215, United States
| |
Collapse
|
27
|
Mao J, Do NN, Scholz F, Reggie L, Mehler M, Lakatos A, Ong YS, Ullrich SJ, Brown LJ, Brown RCD, Becker-Baldus J, Wachtveitl J, Glaubitz C. Structural basis of the green-blue color switching in proteorhodopsin as determined by NMR spectroscopy. J Am Chem Soc 2014; 136:17578-90. [PMID: 25415762 DOI: 10.1021/ja5097946] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Proteorhodopsins (PRs) found in marine microbes are the most abundant retinal-based photoreceptors on this planet. PR variants show high levels of environmental adaptation, as their colors are tuned to the optimal wavelength of available light. The two major green and blue subfamilies can be interconverted through a L/Q point mutation at position 105. Here we reveal the structural basis behind this intriguing color-tuning effect. High-field solid-state NMR spectroscopy was used to visualize structural changes within green PR directly within the lipid bilayer upon introduction of the green-blue L105Q mutation. The observed effects are localized within the binding pocket and close to retinal carbons C14 and C15. Subsequently, magic-angle spinning (MAS) NMR spectroscopy with sensitivity enhancement by dynamic nuclear polarization (DNP) was applied to determine precisely the retinal structure around C14-C15. Upon mutation, a significantly stretched C14-C15 bond, deshielding of C15, and a slight alteration of the retinal chain's out-of-plane twist was observed. The L105Q blue switch therefore acts locally on the retinal itself and induces a conjugation defect between the isomerization region and the imine linkage. Consequently, the S0-S1 energy gap increases, resulting in the observed blue shift. The distortion of the chromophore structure also offers an explanation for the elongated primary reaction detected by pump-probe spectroscopy, while chemical shift perturbations within the protein can be linked to the elongation of late-photocycle intermediates studied by flash photolysis. Besides resolving a long-standing problem, this study also demonstrates that the combination of data obtained from high-field and DNP-enhanced MAS NMR spectroscopy together with time-resolved optical spectroscopy enables powerful synergies for in-depth functional studies of membrane proteins.
Collapse
Affiliation(s)
- Jiafei Mao
- Institute of Biophysical Chemistry and Centre for Biomolecular Magnetic Resonance, Goethe University Frankfurt , 60438 Frankfurt am Main, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Ozaki Y, Kawashima T, Abe-Yoshizumi R, Kandori H. A color-determining amino acid residue of proteorhodopsin. Biochemistry 2014; 53:6032-40. [PMID: 25180875 DOI: 10.1021/bi500842w] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proteorhodopsin (PR) is a light-driven proton pump found in marine bacteria. More than 1000 PRs are classified as blue-absorbing (λmax ∼ 490 nm) and green-absorbing (λmax ∼ 525 nm) PRs. The color determinant is known to be at position 105, where blue-absorbing and green-absorbing PRs possess Gln and Leu, respectively. This suggests hydrophobicity at position 105 plays a key role in color tuning. Here we successfully introduced 19 amino acid residues into position 105 of green-absorbing PR in the membrane environment and investigated the absorption properties. High-performance liquid chromatography analysis shows that the isomeric composition of the all-trans form is >70% for all mutants, indicating little influence of different isomers on color tuning. Absorption spectra of the wild-type and 19 mutant proteins were well-characterized by the pH-dependent equilibria of the protonated and deprotonated counterion (Asp97) of the Schiff base, whereas the λmax values of these two states and the pKa value differed significantly among mutants. Although Gln and Leu are hydrophilic and hydrophobic residues, respectively, the λmax values of the two states and the pKa value did not correlate with the hydropathy index of residues. In contrast, the λmax and pKa were correlated with the volume of residues, though Gln and Leu possess similar volumes. This observation concludes that the λmax and pKa of Asp97 are determined by local and specific interactions in the Schiff base moiety, in which the volume of the residue at position 105 is more influential than its hydrophobicity. We suggest that the hydrogen-bonding network in the Schiff base moiety plays a key role in the λmax and pKa of Asp97, and the hydrogen-bonding network is significantly perturbed by large amino acid residues but may be preserved by additional water molecule(s) for small amino acid residues at position 105.
Collapse
Affiliation(s)
- Yuya Ozaki
- Department of Frontier Materials, Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555, Japan
| | | | | | | |
Collapse
|
29
|
Ogren JI, Mamaev S, Russano D, Li H, Spudich JL, Rothschild KJ. Retinal chromophore structure and Schiff base interactions in red-shifted channelrhodopsin-1 from Chlamydomonas augustae. Biochemistry 2014; 53:3961-70. [PMID: 24869998 PMCID: PMC4072394 DOI: 10.1021/bi500445c] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
![]()
Channelrhodopsins (ChRs), which form
a distinct branch of the microbial
rhodopsin family, control phototaxis in green algae. Because ChRs
can be expressed and function in neuronal membranes as light-gated
cation channels, they have rapidly become an important optogenetic
tool in neurobiology. While channelrhodopsin-2 from the unicellular
alga Chlamydomonas reinhardtii (CrChR2) is the most commonly used and extensively studied optogenetic
ChR, little is known about the properties of the diverse group of
other ChRs. In this study, near-infrared confocal resonance Raman
spectroscopy along with hydrogen–deuterium exchange and site-directed
mutagenesis were used to study the structure of red-shifted ChR1 from Chlamydomonas augustae (CaChR1). These
measurements reveal that (i) CaChR1 has an all-trans-retinal structure similar to those of the light-driven
proton pump bacteriorhodopsin (BR) and sensory rhodopsin II but different
from that of the mixed retinal composition of CrChR2,
(ii) lowering the pH from 7 to 2 or substituting neutral residues
for Glu169 or Asp299 does not significantly shift the ethylenic stretch
frequency more than 1–2 cm–1 in contrast
to BR in which a downshift of 7–9 cm–1 occurs
reflecting neutralization of the Asp85 counterion, and (iii) the CaChR1 protonated Schiff base (SB) has stronger hydrogen
bonding than BR. A model is proposed to explain these results whereby
at pH 7 the predominant counterion to the SB is Asp299 (the homologue
to Asp212 in BR) while Glu169 (the homologue to Asp85 in BR) exists
in a neutral state. We observe an unusual constancy of the resonance
Raman spectra over the broad range from pH 9 to 2 and discuss its
implications. These results are in accord with recent visible absorption
and current measurements of CaChR1 [Sineshchekov,
O. A., et al. (2013) Intramolecular proton transfer in channelrhodopsins. Biophys. J. 104, 807–817; Li, H., et al. (2014) Role
of a helix B lysine residue in the photoactive site in channelrhodopsins. Biophys. J. 106, 1607–1617].
Collapse
Affiliation(s)
- John I Ogren
- Molecular Biophysics Laboratory, Photonics Center, and Department of Physics, Boston University , Boston, Massachusetts 02215, United States
| | | | | | | | | | | |
Collapse
|
30
|
Bamann C, Bamberg E, Wachtveitl J, Glaubitz C. Proteorhodopsin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:614-25. [PMID: 24060527 DOI: 10.1016/j.bbabio.2013.09.010] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/11/2013] [Accepted: 09/13/2013] [Indexed: 10/26/2022]
Abstract
Proteorhodopsins are the most abundant retinal based photoreceptors and their phototrophic function might be relevant in marine ecosystems. Here, we describe their remarkable molecular properties with a special focus on the green absorbing variant. Its distinct features include a high pKa value of the primary proton acceptor stabilized through an interaction with a conserved histidine, a long-range interaction between the cytoplasmic EF loop and the chromophore entailing a particular mode of color tuning and a variable proton pumping vectoriality with complex voltage-dependence. The proteorhodopsin family represents a profound example for structure-function relationships. Especially the development of a biophysical understanding of green proteorhodopsin is an excellent example for the unique opportunities offered by a combined approach of advanced spectroscopic and electrophysiological methods. This article is part of a Special Issue entitled: Retinal Proteins-You can teach an old dog new tricks.
Collapse
Affiliation(s)
- Christian Bamann
- Max Planck Institute of Biophysics, Max-von-Laue Straße 3, 60438 Frankfurt am Main, Germany.
| | - Ernst Bamberg
- Max Planck Institute of Biophysics, Max-von-Laue Straße 3, 60438 Frankfurt am Main, Germany
| | - Josef Wachtveitl
- Johann Wolfgang Goethe University, Institute for Physical and Theoretical Chemistry, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany
| | - Clemens Glaubitz
- Johann Wolfgang Goethe University, Institute for Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany
| |
Collapse
|
31
|
Saint Clair EC, Ogren JI, Mamaev S, Russano D, Kralj JM, Rothschild KJ. Near-IR resonance Raman spectroscopy of archaerhodopsin 3: effects of transmembrane potential. J Phys Chem B 2012. [PMID: 23189985 DOI: 10.1021/jp309996a] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Archaerhodopsin 3 (AR3) is a light driven proton pump from Halorubrum sodomense that has been used as a genetically targetable neuronal silencer and an effective fluorescent sensor of transmembrane potential. Unlike the more extensively studied bacteriorhodopsin (BR) from Halobacterium salinarum, AR3 readily incorporates into the plasma membrane of both E. coli and mammalian cells. Here, we used near-IR resonance Raman confocal microscopy to study the effects of pH and membrane potential on the AR3 retinal chromophore structure. Measurements were performed both on AR3 reconstituted into E. coli polar lipids and in vivo in E. coli expressing AR3 in the absence and presence of a negative transmembrane potential. The retinal chromophore structure of AR3 is in an all-trans configuration almost identical to BR over the entire pH range from 3 to 11. Small changes are detected in the retinal ethylenic stretching frequency and Schiff Base (SB) hydrogen bonding strength relative to BR which may be related to a different water structure near the SB. In the case of the AR3 mutant D95N, at neutral pH an all-trans retinal O-like species (O(all-trans)) is found. At higher pH a second 13-cis retinal N-like species (N(13-cis)) is detected which is attributed to a slowly decaying intermediate in the red-light photocycle of D95N. However, the amount of N(13-cis) detected is less in E. coli cells but is restored upon addition of carbonyl cyanide m-chlorophenyl hydrazone (CCCP) or sonication, both of which dissipate the normal negative membrane potential. We postulate that these changes are due to the effect of membrane potential on the N(13-cis) to M(13-cis) levels accumulated in the D95N red-light photocycle and on a molecular level by the effects of the electric field on the protonation/deprotonation of the cytoplasmic accessible SB. This mechanism also provides a possible explanation for the observed fluorescence dependence of AR3 and other microbial rhodopsins on transmembrane potential.
Collapse
Affiliation(s)
- Erica C Saint Clair
- Department of Physics, Photonics Center and Molecular Biophysics Laboratory, Boston University, Boston, Massachusetts 02215, USA
| | | | | | | | | | | |
Collapse
|
32
|
Maiti TK, Yamada K, Inoue K, Kandori H. L105K Mutant of Proteorhodopsin. Biochemistry 2012; 51:3198-204. [DOI: 10.1021/bi201916a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tushar Kanti Maiti
- Department
of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555,
Japan
| | - Keisuke Yamada
- Department
of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555,
Japan
| | - Keiichi Inoue
- Department
of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555,
Japan
| | - Hideki Kandori
- Department
of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555,
Japan
| |
Collapse
|
33
|
Reckel S, Gottstein D, Stehle J, Löhr F, Verhoefen MK, Takeda M, Silvers R, Kainosho M, Glaubitz C, Wachtveitl J, Bernhard F, Schwalbe H, Güntert P, Dötsch V. Solution NMR structure of proteorhodopsin. Angew Chem Int Ed Engl 2011; 50:11942-6. [PMID: 22034093 PMCID: PMC4234116 DOI: 10.1002/anie.201105648] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Indexed: 11/06/2022]
Affiliation(s)
- Sina Reckel
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438 Frankfurt, Germany, Fax: (+49)-69-798-29632
| | - Daniel Gottstein
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438 Frankfurt, Germany, Fax: (+49)-69-798-29632
| | - Jochen Stehle
- Institute for Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7-9, 60438 Frankfurt, Germany
| | - Frank Löhr
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438 Frankfurt, Germany, Fax: (+49)-69-798-29632
| | - Mirka-Kristin Verhoefen
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438 Frankfurt, Germany
| | - Mitsuhiro Takeda
- Structural Biology Research Center, Nagoya University, Furo‐cho, Chikusa-ku, 464-8601, Japan
| | - Robert Silvers
- Institute for Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7-9, 60438 Frankfurt, Germany
| | - Masatsune Kainosho
- Structural Biology Research Center, Nagoya University, Furo‐cho, Chikusa-ku, 464-8601, Japan; Center for Priority Areas, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Clemens Glaubitz
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438 Frankfurt, Germany, Fax: (+49)-69-798-29632
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438 Frankfurt, Germany
| | - Frank Bernhard
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438 Frankfurt, Germany, Fax: (+49)-69-798-29632
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7-9, 60438 Frankfurt, Germany
| | - Peter Güntert
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438 Frankfurt, Germany, Fax: (+49)-69-798-29632; Frankfurt Institute for Advanced Studies, Goethe University Frankfurt, Ruth-Moufang-Str.1, 60438 Frankfurt am Main, Germany; Center for Priority Areas, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Volker Dötsch
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438 Frankfurt, Germany, Fax: (+49)-69-798-29632
| |
Collapse
|
34
|
Reckel S, Gottstein D, Stehle J, Löhr F, Verhoefen MK, Takeda M, Silvers R, Kainosho M, Glaubitz C, Wachtveitl J, Bernhard F, Schwalbe H, Güntert P, Dötsch V. Solution NMR Structure of Proteorhodopsin. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201105648] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
35
|
Malmerberg E, Omran Z, Hub JS, Li X, Katona G, Westenhoff S, Johansson LC, Andersson M, Cammarata M, Wulff M, van der Spoel D, Davidsson J, Specht A, Neutze R. Time-resolved WAXS reveals accelerated conformational changes in iodoretinal-substituted proteorhodopsin. Biophys J 2011; 101:1345-53. [PMID: 21943415 DOI: 10.1016/j.bpj.2011.07.050] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/15/2011] [Accepted: 07/15/2011] [Indexed: 12/20/2022] Open
Abstract
Time-resolved wide-angle x-ray scattering (TR-WAXS) is an emerging biophysical method which probes protein conformational changes with time. Here we present a comparative TR-WAXS study of native green-absorbing proteorhodopsin (pR) from SAR86 and a halogenated derivative for which the retinal chromophore has been replaced with 13-desmethyl-13-iodoretinal (13-I-pR). Transient absorption spectroscopy differences show that the 13-I-pR photocycle is both accelerated and displays more complex kinetics than native pR. TR-WAXS difference data also reveal that protein structural changes rise and decay an order-of-magnitude more rapidly for 13-I-pR than native pR. Despite these differences, the amplitude and nature of the observed helical motions are not significantly affected by the substitution of the retinal's C-20 methyl group with an iodine atom. Molecular dynamics simulations indicate that a significant increase in free energy is associated with the 13-cis conformation of 13-I-pR, consistent with our observation that the transient 13-I-pR conformational state is reached more rapidly. We conclude that although the conformational trajectory is accelerated, the major transient conformation of pR is unaffected by the substitution of an iodinated retinal chromophore.
Collapse
Affiliation(s)
- Erik Malmerberg
- Department of Chemistry, Biochemistry and Biophysics, University of Gothenburg, Gothenburg, Sweden
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Ranaghan MJ, Shima S, Ramos L, Poulin DS, Whited G, Rajasekaran S, Stuart JA, Albert AD, Birge RR. Photochemical and thermal stability of green and blue proteorhodopsins: implications for protein-based bioelectronic devices. J Phys Chem B 2011; 114:14064-70. [PMID: 20964279 DOI: 10.1021/jp106633w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photochemical and thermal stability of the detergent-solubilized blue- and green-absorbing proteorhodpsins, BPR and GPR, respectively, are investigated to determine the viability of these proteins for photonic device applications. Photochemical stability is studied by using pulsed laser excitation and differential UV-vis spectroscopy to assign the photocyclicity. GPR, with a cyclicity of 7 × 10(4) photocycles protein(-1), is 4-5 times more stable than BPR (9 × 10(3) photocycles protein(-1)), but is less stable than native bacteriorhodopsin (9 × 10(5) photocycles protein(-1)) or the 4-keto-bacteriorhodopsin analogue (1 × 10(5) photocycles protein(-1)). The thermal stabilities are assigned by using differential scanning calorimetry and thermal bleaching experiments. Both proteorhodopsins display excellent thermal stability, with melting temperatures above 85 °C, and remain photochemically stable up to 75 °C. The biological relevance of our results is also discussed. The lower cyclicity of BPR is found to be adequate for the long-term biological function of the host organism at ocean depths of 50 m or more.
Collapse
Affiliation(s)
- Matthew J Ranaghan
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, Connecticut 06269, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
37
|
The retinal structure of channelrhodopsin-2 assessed by resonance Raman spectroscopy. FEBS Lett 2009; 583:3676-80. [PMID: 19854176 DOI: 10.1016/j.febslet.2009.10.052] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2009] [Revised: 10/14/2009] [Accepted: 10/19/2009] [Indexed: 12/19/2022]
Abstract
Channelrhodopsin-2 mediates phototaxis in green algae by acting as a light-gated cation channel. As a result of this property, it is used as a novel optogenetic tool in neurophysiological applications. Structural information is still scant and we present here the first resonance Raman spectra of channelrhodopsin-2. Spectra of detergent solubilized and lipid-reconstituted protein were recorded under pre-resonant conditions to exclusively probe retinal in its electronic ground state. All-trans retinal was identified to be the favoured configuration of the chromophore but significant contributions of 13-cis were detected. Pre-illumination hardly changed the isomeric composition but small amounts of presumably 9-cis retinal were found in the light-adapted state. Spectral analysis suggested that the Schiff base proton is strongly hydrogen-bonded to a nearby water molecule.
Collapse
|
38
|
Amsden JJ, Kralj JM, Bergo VB, Spudich EN, Spudich JL, Rothschild KJ. Different structural changes occur in blue- and green-proteorhodopsins during the primary photoreaction. Biochemistry 2008; 47:11490-8. [PMID: 18842006 DOI: 10.1021/bi800945t] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We examine the structural changes during the primary photoreaction in blue-absorbing proteorhodopsin (BPR), a light-driven retinylidene proton pump, using low-temperature FTIR difference spectroscopy. Comparison of the light-induced BPR difference spectrum recorded at 80 K to that of green-absorbing proteorhodopsin (GPR) reveals that there are several differences in the BPR and GPR primary photoreactions despite the similar structure of the retinal chromophore and all-trans --> 13-cis isomerization. Strong bands near 1700 cm(-1) assigned previously to a change in hydrogen bonding of Asn230 in GPR are still present in BPR. However, additional bands in the same region are assigned on the basis of site-directed mutagenesis to changes occurring in Gln105. In the amide II region, bands are assigned on the basis of total (15)N labeling to structural changes of the protein backbone, although no such bands were previously observed for GPR. A band at 3642 cm(-1) in BPR, assigned to the OH stretching mode of a water molecule on the basis of H2(18)O substitution, appears at a different frequency than a band at 3626 cm(-1) previously assigned to a water molecule in GPR. However, the substitution of Gln105 for Leu105 in BPR leads to the appearance of both bands at 3642 and 3626 cm(-1), indicating the waters assigned in BPR and GPR exist in separate distinct locations and can coexist in the GPR-like Q105L mutant of BPR. These results indicate that there exist significant differences in the conformational changes occurring in these two types proteorhodopsin during the initial photoreaction despite their similar chromophore structures, which might reflect a different arrangement of water in the active site as well as substitution of a hydrophilic for hydrophobic residue at residue 105.
Collapse
Affiliation(s)
- Jason J Amsden
- Department of Physics, Photonics Center, and Molecular Biophysics Laboratory, Boston University, Boston, Massachusetts 02215, USA
| | | | | | | | | | | |
Collapse
|