1
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Suzuki T, Yoshimura M, Arai M, Narikawa R. Crucial Residue for Tuning Thermal Relaxation Kinetics in the Biliverdin-binding Cyanobacteriochrome Photoreceptor Revealed by Site-saturation Mutagenesis. J Mol Biol 2024; 436:168451. [PMID: 38246412 DOI: 10.1016/j.jmb.2024.168451] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 01/23/2024]
Abstract
Cyanobacteriochromes (CBCRs) are cyanobacterial photoreceptors distantly related to the phytochromes sensing red and far-red light reversibly. Only the cGMP phosphodiesterase/Adenylate cyclase/FhlA (GAF) domain is needed for chromophore incorporation and proper photoconversion. The CBCR GAF domains covalently ligate linear tetrapyrrole chromophores and show reversible photoconversion between two light-absorbing states. In most cases, the two light-absorbing states are stable under dark conditions, but in some cases, the photoproduct state undergoes thermal relaxation back to the dark-adapted state during thermal relaxation. In this study, we examined the engineered CBCR GAF domain, AnPixJg2_BV4. AnPixJg2_BV4 covalently binds biliverdin IX-alpha (BV) and shows reversible photoconversion between a far-red-absorbing Pfr dark-adapted state and an orange-absorbing Po photoproduct state. Because the BV is an intrinsic chromophore of mammalian cells and absorbs far-red light penetrating into deep tissues, BV-binding CBCR molecules are useful for the development of optogenetic and bioimaging tools used in mammals. To obtain a better developmental platform molecule, we performed site-saturation random mutagenesis on the Phe319 position. We succeeded in obtaining variant molecules with higher chromophore-binding efficiency and higher molar extinction coefficient. Furthermore, we observed a wide variation in thermal relaxation kinetics, with an 81-fold difference between the slowest and fastest rates. Both molecules with relatively slow and fast thermal relaxation would be advantageous for optogenetic control.
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Affiliation(s)
- Takahisa Suzuki
- Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397, Japan.
| | - Masataka Yoshimura
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan
| | - Munehito Arai
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan; Department of Physics, Graduate School of Science, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan
| | - Rei Narikawa
- Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397, Japan.
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2
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Takeda Y, Ohtsu I, Suzuki T, Nakasone Y, Fushimi K, Ikeuchi M, Terazima M, Dohra H, Narikawa R. Conformational change in an engineered biliverdin-binding cyanobacteriochrome during the photoconversion process. Arch Biochem Biophys 2023; 745:109715. [PMID: 37549803 DOI: 10.1016/j.abb.2023.109715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 08/02/2023] [Accepted: 08/05/2023] [Indexed: 08/09/2023]
Abstract
Cyanobacteriochromes (CBCRs) derived from cyanobacteria are linear-tetrapyrrole-binding photoreceptors related to the canonical red/far-red reversible phytochrome photoreceptors. CBCRs contain chromophore-binding cGMP-specific phosphodiesterase/adenylate cyclase/FhlA (GAF) domains that are highly diverse in their primary sequences and are categorized into many subfamilies. Among this repertoire, the biliverdin (BV)-binding CBCR GAF domains receive considerable attention for their in vivo optogenetic and bioimaging applications because BV is a mammalian intrinsic chromophore and can absorb far-red light that penetrates deep into the mammalian body. The typical BV-binding CBCR GAF domain exhibits reversible photoconversion between far-red-absorbing dark-adapted and orange-absorbing photoproduct states. Herein, we applied various biochemical and spectral studies to identify the details of the conformational change during this photoconversion process. No oligomeric state change was observed, whereas the surface charge would change with a modification of the α-helix structures during the photoconversion process. Combinatorial analysis using partial protease digestion and mass spectrometry identified the region where the conformational change occurred. These results provide clues for the future development of optogenetic tools.
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Affiliation(s)
- Yuka Takeda
- Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga, Shizuoka, 422-8529, Japan
| | - Itsuki Ohtsu
- Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga, Shizuoka, 422-8529, Japan
| | - Takahisa Suzuki
- Graduate School of Biological Sciences, Faculty of Science, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo, 192-0397, Japan
| | - Yusuke Nakasone
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Keiji Fushimi
- Graduate School of Science, Technology and Innovation, Kobe University, Hyogo, 657-0013, Japan
| | - Masahiko Ikeuchi
- Graduate School of Biological Sciences, Faculty of Science, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo, 192-0397, Japan
| | - Masahide Terazima
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Hideo Dohra
- Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga, Shizuoka, 422-8529, Japan; Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga, Shizuoka, 422-8529, Japan
| | - Rei Narikawa
- Graduate School of Biological Sciences, Faculty of Science, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo, 192-0397, Japan.
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Buhrke D, Lahav Y, Rao A, Ruf J, Schapiro I, Hamm P. Transient 2D IR Spectroscopy and Multiscale Simulations Reveal Vibrational Couplings in the Cyanobacteriochrome Slr1393-g3. J Am Chem Soc 2023. [PMID: 37450891 DOI: 10.1021/jacs.3c00896] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
Cyanobacteriochromes are bistable photoreceptor proteins with desirable photochemical properties for biotechnological applications, such as optogenetics or fluorescence microscopy. Here, we investigate Slr1393-g3, a cyanobacteriochrome that reversibly photoswitches between a red-absorbing (Pr) and green-absorbing (Pg) form. We applied advanced IR spectroscopic methods to track the sequence of intermediates during the photocycle over many orders of magnitude in time. In the conversion from Pg to Pr, we have revealed a new intermediate with distinct spectroscopic features in the IR, which precedes Pr formation using transient IR spectroscopy. In addition, stationary and transient 2D IR experiments measured the vibrational couplings between different groups of the chromophore and the protein in these intermediate states, as well as their structural disorder. Anharmonic QM/MM calculations predict spectra in good agreement with experimental 2D IR spectra of the initial and final states of the photocycle. They facilitate the assignment of the IR spectra that serve as a basis for the interpretation of the spectroscopic results and suggest structural changes of the intermediates along the photocycle.
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Affiliation(s)
- David Buhrke
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
- Institute of Biology, Humboldt University Berlin, 10115 Berlin, Germany
| | - Yigal Lahav
- Fritz Haber Center for Molecular Dynamics, Hebrew University of Jerusalem, 9190401 Jerusalem, Israel
- MIGAL - Galilee Research Institute, 1101602 Kiryat Shmona, Israel
| | - Aditya Rao
- Fritz Haber Center for Molecular Dynamics, Hebrew University of Jerusalem, 9190401 Jerusalem, Israel
| | - Jeannette Ruf
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics, Hebrew University of Jerusalem, 9190401 Jerusalem, Israel
| | - Peter Hamm
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
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4
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Wu XJ, Qu JY, Wang CT, Zhang YP, Li PP. Biliverdin incorporation into the cyanobacteriochrome SPI1085g3 from Spirulina. Front Microbiol 2022; 13:952678. [PMID: 35983329 PMCID: PMC9378818 DOI: 10.3389/fmicb.2022.952678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 07/11/2022] [Indexed: 11/14/2022] Open
Abstract
Cyanobacteriochromes (CBCRs) bind linear tetrapyrrole chromophores, mostly phycocyanobilin (PCB), and exhibit considerable spectral diversity with a high potential for biotechnological applications. Particular attention has been given to the conversion into intrinsic biliverdin (BV) incorporation due to the absence of PCB in mammalian cells. Our recent study discovered that a red/green CBCR of Spirulina subsalsa, SPI1085g3, was covalently attached to PCB and exhibited strong red fluorescence with a unique red/dark switch. In this study, we found that SPI1085g3 could be modestly chromophorylated with BV and absorb somewhat shifted (10 nm) red light, while the single C448S mutant could efficiently bind BV and exhibit unidirectional photoconversion and moderate dark reversion. The fluorescence in its dark-adapted state was switched off by red light, followed by a moderate recovery in the dark, and these were properties similar to those of PCB-binding SPI1085g3. Furthermore, by introducing the CY motif into the conserved CH motif for chromophore attachment, we developed another variant, C448S_CY, which showed increased BV-binding efficiency. As expected, C448S_CY had a significant enhancement in fluorescence quantum yield, reaching that of PCB-binding SPI1085g3 (0.14). These BV-binding CBCRs offer an improved platform for the development of unique photoswitchable fluorescent proteins compared with PCB-binding CBCRs.
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Affiliation(s)
- Xian-Jun Wu
- College of Biology and the Environment, Nanjing Forestry University, Nanjing, China
- Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing, China
- National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, China
- *Correspondence: Xian-Jun Wu,
| | - Jia-Ying Qu
- College of Biology and the Environment, Nanjing Forestry University, Nanjing, China
| | - Chang-Tian Wang
- College of Biology and the Environment, Nanjing Forestry University, Nanjing, China
| | - Ya-Ping Zhang
- College of Biology and the Environment, Nanjing Forestry University, Nanjing, China
| | - Ping-Ping Li
- College of Biology and the Environment, Nanjing Forestry University, Nanjing, China
- Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing, China
- National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, China
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5
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Rockwell NC, Moreno MV, Martin SS, Lagarias JC. Protein-chromophore interactions controlling photoisomerization in red/green cyanobacteriochromes. Photochem Photobiol Sci 2022; 21:471-491. [PMID: 35411484 PMCID: PMC9609751 DOI: 10.1007/s43630-022-00213-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/21/2022] [Indexed: 10/18/2022]
Abstract
Photoreceptors in the phytochrome superfamily use 15,16-photoisomerization of a linear tetrapyrrole (bilin) chromophore to photoconvert between two states with distinct spectral and biochemical properties. Canonical phytochromes include master regulators of plant growth and development in which light signals trigger interconversion between a red-absorbing 15Z dark-adapted state and a metastable, far-red-absorbing 15E photoproduct state. Distantly related cyanobacteriochromes (CBCRs) carry out a diverse range of photoregulatory functions in cyanobacteria and exhibit considerable spectral diversity. One widespread CBCR subfamily typically exhibits a red-absorbing 15Z dark-adapted state similar to that of phytochrome that gives rise to a distinct green-absorbing 15E photoproduct. This red/green CBCR subfamily also includes red-inactive examples that fail to undergo photoconversion, providing an opportunity to study protein-chromophore interactions that either promote photoisomerization or block it. In this work, we identified a conserved lineage of red-inactive CBCRs. This enabled us to identify three substitutions sufficient to block photoisomerization in photoactive red/green CBCRs. The resulting red-inactive variants faithfully replicated the fluorescence and circular dichroism properties of naturally occurring examples. Converse substitutions restored photoconversion in naturally red-inactive CBCRs. This work thus identifies protein-chromophore interactions that control the fate of the excited-state population in red/green cyanobacteriochromes.
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Affiliation(s)
- Nathan C Rockwell
- Department of Molecular and Cellular Biology, University of California at Davis, Davis, CA, 95616, USA.
| | - Marcus V Moreno
- Department of Molecular and Cellular Biology, University of California at Davis, Davis, CA, 95616, USA
| | - Shelley S Martin
- Department of Molecular and Cellular Biology, University of California at Davis, Davis, CA, 95616, USA
| | - J Clark Lagarias
- Department of Molecular and Cellular Biology, University of California at Davis, Davis, CA, 95616, USA.
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6
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Buhrke D. The impact of chromophore choice on the assembly kinetics and primary photochemistry of a red/green cyanobacteriochrome. Phys Chem Chem Phys 2021; 23:20867-20874. [PMID: 34374395 PMCID: PMC8479780 DOI: 10.1039/d1cp02696h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/04/2021] [Indexed: 11/24/2022]
Abstract
Cyanobacteriochromes (CBCRs) are bi-stable photoreceptor proteins with high potential for biotechnological applications. Most of these proteins utilize phycocyanobilin (PCB) as a light-sensing co-factor, which is unique to cyanobacteria, but some variants also incorporate biliverdin (BV). The latter are of particular interest for biotechnology due to the natural abundance and red-shifted absorption of BV. Here, AmI-g2 was investigated, a CBCR capable of binding both PCB and BV. The assembly kinetics and primary photochemistry of AmI-g2 with both chromophores were studied in vitro. The assembly reaction with PCB is roughly 10× faster than BV, and the formation of a non-covalent intermediate was identified as the rate-limiting step in the case of BV. This step is fast for PCB, where the formation of the covalent thioether bond between AmI-g2 and PCB becomes rate-limiting. The photochemical quantum yields of the forward and backward reactions of AmI-g2 were estimated and discussed in the context of homologous CBCRs.
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Affiliation(s)
- David Buhrke
- Department of Chemistry, University of Zürich, Zürich, Switzerland.
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7
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An Engineered Biliverdin-Compatible Cyanobacteriochrome Enables a Unique Ultrafast Reversible Photoswitching Pathway. Int J Mol Sci 2021; 22:ijms22105252. [PMID: 34065754 PMCID: PMC8156171 DOI: 10.3390/ijms22105252] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/09/2021] [Accepted: 05/14/2021] [Indexed: 11/17/2022] Open
Abstract
Cyanobacteriochromes (CBCRs) are promising optogenetic tools for their diverse absorption properties with a single compact cofactor-binding domain. We previously uncovered the ultrafast reversible photoswitching dynamics of a red/green photoreceptor AnPixJg2, which binds phycocyanobilin (PCB) that is unavailable in mammalian cells. Biliverdin (BV) is a mammalian cofactor with a similar structure to PCB but exhibits redder absorption. To improve the AnPixJg2 feasibility in mammalian applications, AnPixJg2_BV4 with only four mutations has been engineered to incorporate BV. Herein, we implemented femtosecond transient absorption (fs-TA) and ground state femtosecond stimulated Raman spectroscopy (GS-FSRS) to uncover transient electronic dynamics on molecular time scales and key structural motions responsible for the photoconversion of AnPixJg2_BV4 with PCB (Bpcb) and BV (Bbv) cofactors in comparison with the parent AnPixJg2 (Apcb). Bpcb adopts the same photoconversion scheme as Apcb, while BV4 mutations create a less bulky environment around the cofactor D ring that promotes a faster twist. The engineered Bbv employs a reversible clockwise/counterclockwise photoswitching that requires a two-step twist on ~5 and 35 picosecond (ps) time scales. The primary forward Pfr → Po transition displays equal amplitude weights between the two processes before reaching a conical intersection. In contrast, the primary reverse Po → Pfr transition shows a 2:1 weight ratio of the ~35 ps over 5 ps component, implying notable changes to the D-ring-twisting pathway. Moreover, we performed pre-resonance GS-FSRS and quantum calculations to identify the Bbv vibrational marker bands at ~659,797, and 1225 cm-1. These modes reveal a stronger H-bonding network around the BV cofactor A ring with BV4 mutations, corroborating the D-ring-dominant reversible photoswitching pathway in the excited state. Implementation of BV4 mutations in other PCB-binding GAF domains like AnPixJg4, AM1_1870g3, and NpF2164g5 could promote similar efficient reversible photoswitching for more directional bioimaging and optogenetic applications, and inspire other bioengineering advances.
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8
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Ruf J, Hamm P, Buhrke D. Needles in a haystack: H-bonding in an optogenetic protein observed with isotope labeling and 2D-IR spectroscopy. Phys Chem Chem Phys 2021; 23:10267-10273. [PMID: 33899887 PMCID: PMC8099029 DOI: 10.1039/d1cp00996f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 04/09/2021] [Indexed: 11/29/2022]
Abstract
Recently, re-purposing of cyanobacterial photoreceptors as optogentic actuators enabled light-regulated protein expression in different host systems. These new bi-stable optogenetic tools enable interesting new applications, but their light-driven working mechanism remains largely elusive on a molecular level. Here, we study the optogenetic cyanobacteriochrome Am1-c0023g2 with isotope labeling and two dimensional infrared (2D-IR) spectroscopy. Isotope labeling allows us to isolate two site-specific carbonyl marker modes from the overwhelming mid-IR signal of the peptide backbone vibrations. Unlike conventional difference-FTIR spectroscopy, 2D-IR is sensitive to homogeneous and inhomogeneous broadening mechanisms of these two vibrational probes in the different photostates of the protein. We analyse the 2D-IR line shapes in the context of available structural models and find that they reflect the hydrogen-bonding environment of these two marker groups.
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Affiliation(s)
- Jeannette Ruf
- Department of Chemistry, University of Zürich, Zürich, Switzerland.
| | - Peter Hamm
- Department of Chemistry, University of Zürich, Zürich, Switzerland.
| | - David Buhrke
- Department of Chemistry, University of Zürich, Zürich, Switzerland.
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9
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Rao AG, Wiebeler C, Sen S, Cerutti DS, Schapiro I. Histidine protonation controls structural heterogeneity in the cyanobacteriochrome AnPixJg2. Phys Chem Chem Phys 2021; 23:7359-7367. [PMID: 33876095 DOI: 10.1039/d0cp05314g] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Cyanobacteriochromes are compact and spectrally diverse photoreceptor proteins that bind a linear tetrapyrrole as a chromophore. They show photochromicity by having two stable states that can be interconverted by the photoisomerization of the chromophore. These photochemical properties make them an attractive target for biotechnological applications. However, their application is impeded by structural heterogeneity that reduces the yield of the photoconversion. The heterogeneity can originate either from the chromophore structure or the protein environment. Here, we study the origin of the heterogeneity in AnPixJg2, a representative member of the red/green cyanobacteriochrome family, that has a red absorbing parental state and a green absorbing photoproduct state. Using molecular dynamics simulations and umbrella sampling we have identified the protonation state of a conserved histidine residue as a trigger for structural heterogeneity. When the histidine is in a neutral form, the chromophore structure is homogenous, while in a positively charged form, the chromophore is heterogeneous with two different conformations. We have identified a correlation between the protonation of the histidine and the structural heterogeneity of the chromophore by detailed characterization of the interactions in the protein binding site. Our findings reconcile seemingly contradicting spectroscopic studies that attribute the heterogeneity to different sources. Furthermore, we predict that circular dichroism can be used as a diagnostic tool to distinguish different substates.
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Affiliation(s)
- Aditya G Rao
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
| | - Christian Wiebeler
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
| | - Saumik Sen
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
| | - David S Cerutti
- Department of Chemistry and Chemical Biology, Rutgers University, USA
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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