1
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Hildebrandt P. Vibrational Spectroscopy of Phytochromes. Biomolecules 2023; 13:1007. [PMID: 37371587 DOI: 10.3390/biom13061007] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 06/12/2023] [Accepted: 06/14/2023] [Indexed: 06/29/2023] Open
Abstract
Phytochromes are biological photoswitches that translate light into physiological functions. Spectroscopic techniques are essential tools for molecular research into these photoreceptors. This review is directed at summarizing how resonance Raman and IR spectroscopy contributed to an understanding of the structure, dynamics, and reaction mechanism of phytochromes, outlining the substantial experimental and theoretical challenges and describing the strategies to master them. It is shown that the potential of the various vibrational spectroscopic techniques can be most efficiently exploited using integral approaches via a combination of theoretical methods as well as other experimental techniques.
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Affiliation(s)
- Peter Hildebrandt
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Straße des 17. Juni 135, D-10623 Berlin, Germany
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2
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Kikuchi H. Redshifting and Blueshifting of β82 Chromophores in the Phycocyanin Hexamer of Porphyridium purpureum Phycobilisomes Due to Linker Proteins. Life (Basel) 2022; 12:1833. [PMID: 36362988 PMCID: PMC9694638 DOI: 10.3390/life12111833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/03/2022] [Accepted: 11/07/2022] [Indexed: 09/10/2024] Open
Abstract
Phycobilisomes in cyanobacteria and red algae are large protein complexes that absorb light and transfer energy for use in photosynthesis. The light energy absorbed by chromophores binding to phycobiliproteins in the peripheral rods can be funneled to the core through chromophores at very high efficiency. The molecular mechanism of excitation energy transfer within a phycobilisome is an example of a higher and unique function in a living organism. However, the mechanism underlying the high efficiency remains unclear. Thus, this study was carried out as a step to resolve this mechanism theoretically. The three-dimensional structure of phycobilisomes containing the linker proteins of the red alga Porphyridium purpureum was determined by cryoelectron microscopy at 2.82 Å resolution in 2020. Using these data, the absorption wavelength of each β82 chromophore in the phycocyanin hexamer located next to the core was calculated using quantum chemical treatment, considering the electric effect from its surrounding phycocyanin proteins and two linker proteins. In addition to unaffected chromophores, chromophores that were redshifted and blueshifted under the electrical influence of the two linker proteins were found. Namely, the chromophore serving as the energy sink in the rod was determined.
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Affiliation(s)
- Hiroto Kikuchi
- Department of Physics, Nippon Medical School, 1-7-1 Kyonan-cho, Musashino, Tokyo 180-0023, Japan
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3
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Sil S, Tilluck RW, Mohan T M N, Leslie CH, Rose JB, Domínguez-Martín MA, Lou W, Kerfeld CA, Beck WF. Excitation energy transfer and vibronic coherence in intact phycobilisomes. Nat Chem 2022; 14:1286-1294. [PMID: 36123451 DOI: 10.1038/s41557-022-01026-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 07/21/2022] [Indexed: 11/09/2022]
Abstract
The phycobilisome is an oligomeric chromoprotein complex that serves as the principal mid-visible light-harvesting system in cyanobacteria. Here we report the observation of excitation-energy-transfer pathways involving delocalized optical excitations of the bilin (linear tetrapyrrole) chromophores in intact phycobilisomes isolated from Fremyella diplosiphon. By using broadband multidimensional electronic spectroscopy with 6.7-fs laser pulses, we are able to follow the progress of excitation energy from the phycoerythrin disks at the ends of the phycobilisome's rods to the C-phycocyanin disks along their length in <600 fs. Oscillation maps show that coherent wavepacket motions prominently involving the hydrogen out-of-plane vibrations of the bilins mediate non-adiabatic relaxation of a manifold of vibronic exciton states. However, the charge-transfer character of the bilins in the allophycocyanin-containing segments localizes the excitations in the core of the phycobilisome, yielding a kinetic bottleneck that enables photoregulatory mechanisms to operate efficiently on the >10-ps timescale.
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Affiliation(s)
- Sourav Sil
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Ryan W Tilluck
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Nila Mohan T M
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Chase H Leslie
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Justin B Rose
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | | | - Wenjing Lou
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
| | - Cheryl A Kerfeld
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
| | - Warren F Beck
- Department of Chemistry, Michigan State University, East Lansing, MI, USA.
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4
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Okuda Y, Miyoshi R, Kamo T, Fujisawa T, Nagae T, Mishima M, Eki T, Hirose Y, Unno M. Raman Spectroscopy of an Atypical C15-E,syn Bilin Chromophore in Cyanobacteriochrome RcaE. J Phys Chem B 2022; 126:813-821. [DOI: 10.1021/acs.jpcb.1c09652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yuji Okuda
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Risako Miyoshi
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Takanari Kamo
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
| | - Tomotsumi Fujisawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Takayuki Nagae
- Synchrotron Radiation Research Center, Nagoya University, Chikusa, Nagoya 464-8603, Japan
| | - Masaki Mishima
- Department of Molecular Biophysics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Toshihiko Eki
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
| | - Yuu Hirose
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
| | - Masashi Unno
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
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5
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Kraskov A, Buhrke D, Scheerer P, Shaef I, Sanchez JC, Carrillo M, Noda M, Feliz D, Stojković EA, Hildebrandt P. On the Role of the Conserved Histidine at the Chromophore Isomerization Site in Phytochromes. J Phys Chem B 2021; 125:13696-13709. [PMID: 34843240 DOI: 10.1021/acs.jpcb.1c08245] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phytochromes are sensory photoreceptors that use light to drive protein structural changes, which in turn trigger physiological reaction cascades. The process starts with a double-bond photoisomerization of the linear methine-bridged tetrapyrrole chromophore in the photosensory core module. The molecular mechanism of the photoconversion depends on the structural and electrostatic properties of the chromophore environment, which are highly conserved in related phytochromes. However, the specific role of individual amino acids is yet not clear. A histidine in the vicinity of the isomerization site is highly conserved and almost invariant among all phytochromes. The present study aimed at analyzing its role by taking advantage of a myxobacterial phytochrome SaBphP1 from Stigmatella aurantiaca, where this histidine is naturally substituted with a threonine (Thr289), and comparing it to its normal, His-containing counterpart from the same organism SaBphP2 (His275). We have carried out a detailed resonance Raman and IR spectroscopic investigation of the wild-type proteins and their respective His- or Thr-substituted variants (SaBphP1-T289H and SaBphP2-H275T) using the well-characterized prototypical phytochrome Agp1 from Agrobacterium fabrum as a reference. The overall mechanism of the photoconversion is insensitive toward the His substitution. However, the chromophore geometry at the isomerization site appears to be affected, with a slightly stronger twist of ring D in the presence of Thr, which is sufficient to cause different light absorption properties in SaBphP1 and SaBphP2. Furthermore, the presence of His allows for multiple hydrogen-bonding interactions with the ring D carbonyl which may be the origin for the geometric differences of the C-D methine bridge compared to the Thr-containing variants. Other structural and mechanistic differences are independent of the presence of His. The most striking finding is the protonation of the ring C propionate in the Pfr states of SaBphP2, which is common among bathy phytochromes but so far has not been reported in prototypical phytochromes.
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Affiliation(s)
- Anastasia Kraskov
- Institut für Chemie, Technische Universität Berlin, Sekr. PC14, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - David Buhrke
- Institut für Chemie, Technische Universität Berlin, Sekr. PC14, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Patrick Scheerer
- Charité─Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, D-10117 Berlin, Germany
| | - Ida Shaef
- Institut für Chemie, Technische Universität Berlin, Sekr. PC14, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Juan C Sanchez
- Department of Biology, Northeastern Illinois University, 5500 North St. Louis Avenue, Chicago, Illinois 60625, United States
| | - Melissa Carrillo
- Department of Biology, Northeastern Illinois University, 5500 North St. Louis Avenue, Chicago, Illinois 60625, United States
| | - Moraima Noda
- Department of Biology, Northeastern Illinois University, 5500 North St. Louis Avenue, Chicago, Illinois 60625, United States
| | - Denisse Feliz
- Department of Biology, Northeastern Illinois University, 5500 North St. Louis Avenue, Chicago, Illinois 60625, United States
| | - Emina A Stojković
- Department of Biology, Northeastern Illinois University, 5500 North St. Louis Avenue, Chicago, Illinois 60625, United States
| | - Peter Hildebrandt
- Institut für Chemie, Technische Universität Berlin, Sekr. PC14, Straße des 17. Juni 135, D-10623 Berlin, Germany
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6
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Kikuchi H. Functional roles of the hexamer structure of C-phycocyanin revealed by calculation of absorption wavelength. FEBS Open Bio 2021; 11:164-172. [PMID: 33190413 PMCID: PMC7780113 DOI: 10.1002/2211-5463.13038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/27/2020] [Accepted: 11/11/2020] [Indexed: 11/11/2022] Open
Abstract
Cyanophyta-phycocyanin (C-PC) is the main constituent of the rod of phycobilisome (PBS), which is a highly ordered and large peripheral light-harvesting protein complex present on the cytoplasmic side of the thylakoid membrane in cyanobacteria and red algae. The C-PC monomer comprises two chains, α- and β-subunits, and aggregates to form ring-shaped trimers (αβ)3 with rotational symmetry. The ring-shaped trimer (αβ)3 is a structural block unit (SBU) that forms the rod of PBS. Two (αβ)3 SBUs are arranged in a face-to-face manner to form an (αβ)6 -hexamer. In this study, the electronic states of three phycocyanobilins, α84, β84, and β155 in C-phycocyanin, constituting the rod of the PBS, were calculated for both the trimer and hexamer models by considering the effect of the electrostatic field of protein moieties and water molecules. For the hexamer, the absorption wavelengths of α84, β84, and β155 were similar to those obtained experimentally; however, for the trimer, only the absorption wavelength of β155 shifted toward a shorter-wavelength. The nature of the hexamer structure as a hierarchical structure is revealed by considering the calculated absorption wavelength and energy transfer.
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Affiliation(s)
- Hiroto Kikuchi
- Department of PhysicsNippon Medical SchoolMusashinoJapan
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7
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Sato T, Kikukawa T, Miyoshi R, Kajimoto K, Yonekawa C, Fujisawa T, Unno M, Eki T, Hirose Y. Protochromic absorption changes in the two-cysteine photocycle of a blue/orange cyanobacteriochrome. J Biol Chem 2019; 294:18909-18922. [PMID: 31649035 DOI: 10.1074/jbc.ra119.010384] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/23/2019] [Indexed: 11/06/2022] Open
Abstract
Cyanobacteriochromes (CBCRs) are phytochrome-related photosensors with diverse spectral sensitivities spanning the entire visible spectrum. They covalently bind bilin chromophores via conserved cysteine residues and undergo 15Z/15E bilin photoisomerization upon light illumination. CBCR subfamilies absorbing violet-blue light use an additional cysteine residue to form a second bilin-thiol adduct in a two-Cys photocycle. However, the process of second thiol adduct formation is incompletely understood, especially the involvement of the bilin protonation state. Here, we focused on the Oscil6304_2705 protein from the cyanobacterium Oscillatoria acuminata PCC 6304, which photoconverts between a blue-absorbing 15Z state ( 15Z Pb) and orange-absorbing 15E state ( 15E Po). pH titration analysis revealed that 15Z Pb was stable over a wide pH range, suggesting that bilin protonation is stabilized by a second thiol adduct. As revealed by resonance Raman spectroscopy, 15E Po harbored protonated bilin at both acidic and neutral pH, but readily converted to a deprotonated green-absorbing 15Z state ( 15Z Pg) at alkaline pH. Site-directed mutagenesis revealed that the conserved Asp-71 and His-102 residues are required for second thiol adduct formation in 15Z Pb and bilin protonation in 15E Po, respectively. An Oscil6304_2705 variant lacking the second cysteine residue, Cys-73, photoconverted between deprotonated 15Z Pg and protonated 15E Pr, similarly to the protochromic photocycle of the green/red CBCR subfamily. Time-resolved spectroscopy revealed 15Z Pg formation as an intermediate in the 15E Pr-to- 15Z Pg conversion with a significant solvent-isotope effect, suggesting the sequential occurrence of 15EP-to-15Z photoisomerization, deprotonation, and second thiol adduct formation. Our findings uncover the details of protochromic absorption changes underlying the two-Cys photocycle of violet-blue-absorbing CBCR subfamilies.
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Affiliation(s)
- Teppei Sato
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580, Japan
| | - Takashi Kikukawa
- Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Kita10 Nishi8, Kita-ku, Sapporo 060-0810, Japan; Faculty of Advanced Life Science, Hokkaido University, Kita10 Nishi8, Kita-ku, Sapporo 060-0810, Japan
| | - Risako Miyoshi
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Kousuke Kajimoto
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Chinatsu Yonekawa
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580, Japan
| | - Tomotsumi Fujisawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Masashi Unno
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Toshihiko Eki
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580, Japan
| | - Yuu Hirose
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580, Japan.
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8
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Osoegawa S, Miyoshi R, Watanabe K, Hirose Y, Fujisawa T, Ikeuchi M, Unno M. Identification of the Deprotonated Pyrrole Nitrogen of the Bilin-Based Photoreceptor by Raman Spectroscopy with an Advanced Computational Analysis. J Phys Chem B 2019; 123:3242-3247. [PMID: 30913882 DOI: 10.1021/acs.jpcb.9b00965] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phytochrome and cyanobacteriochrome utilize a linear methine-bridged tetrapyrrole (bilin) to control numerous biological processes. They show a reversible photoconversion between two spectrally distinct states. This photocycle is initiated by a C═C double-bond photoisomerization of the bilin followed by its thermal relaxations with transient and/or stationary changes in the protonation state of the pyrrole moiety. However, it has never been identified which of the four pyrrole nitrogen atoms is deprotonated. Here, we report a resonance Raman spectroscopic study on cyanobacteriochrome RcaE, which has been proposed to contain a deprotonated bilin for its green-absorbing 15 Z state. The observed Raman spectra were well reproduced by a simulated structure whose bilin B ring is deprotonated, with the aid of molecular dynamics and quantum mechanics/molecular mechanics calculations. The results revealed that the deprotonation of B and C rings has the distinct effect on the overall bilin structure, which will be relevant to the color tuning and photoconversion mechanisms of the phytochrome superfamily. Furthermore, this study documents the ability of vibrational spectroscopy combined with the advanced spectral analysis to visualize a proton of a cofactor molecule embedded in a protein moiety.
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Affiliation(s)
- Shinsuke Osoegawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering , Saga University , Saga 840-8502 , Japan
| | - Risako Miyoshi
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering , Saga University , Saga 840-8502 , Japan
| | - Kouhei Watanabe
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering , Saga University , Saga 840-8502 , Japan
| | - Yuu Hirose
- Department of Environmental and Life Sciences , Toyohashi University of Technology , Toyohashi , Aichi 441-8580 , Japan
| | - Tomotsumi Fujisawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering , Saga University , Saga 840-8502 , Japan
| | - Masahiko Ikeuchi
- Department of Life Sciences (Biology) , The University of Tokyo , Meguro, Tokyo 153-8902 , Japan
| | - Masashi Unno
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering , Saga University , Saga 840-8502 , Japan
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9
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Modi V, Donnini S, Groenhof G, Morozov D. Protonation of the Biliverdin IXα Chromophore in the Red and Far-Red Photoactive States of a Bacteriophytochrome. J Phys Chem B 2019; 123:2325-2334. [PMID: 30762368 PMCID: PMC6727380 DOI: 10.1021/acs.jpcb.9b01117] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
![]()
The
tetrapyrrole chromophore biliverdin IXα (BV) in the bacteriophytochrome
from Deinococcus radiodurans (DrBphP)
is usually assumed to be fully protonated, but this assumption has
not been systematically validated by experiments or extensive computations.
Here, we use force field molecular dynamics simulations and quantum
mechanics/molecular mechanics calculations with density functional
theory and XMCQDPT2 methods to investigate the effect of the five
most probable protonation forms of BV on structural stability, binding
pocket interactions, and absorption spectra in the two photochromic
states of DrBphP. While agreement with X-ray structural data and measured
UV/vis spectra suggest that in both states the protonated form of
the chromophore dominates, we also find that a minor population with
a deprotonated D-ring could contribute to the red-shifted tail in
the absorption spectra.
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10
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Inakollu VSS, Yu H. A systematic benchmarking of computational vibrational spectroscopy with DFTB3: Normal mode analysis and fast Fourier transform dipole autocorrelation function. J Comput Chem 2018; 39:2067-2078. [DOI: 10.1002/jcc.25390] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 06/04/2018] [Accepted: 06/12/2018] [Indexed: 11/10/2022]
Affiliation(s)
- V. S. Sandeep Inakollu
- School of Chemistry and Molecular Bioscience University of Wollongong Wollongong New South Wales 2522 Australia
- Molecular Horizons University of Wollongong New South Wales 2522 Australia
| | - Haibo Yu
- School of Chemistry and Molecular Bioscience University of Wollongong Wollongong New South Wales 2522 Australia
- Molecular Horizons University of Wollongong New South Wales 2522 Australia
- Illawarra Health and Medical Research Institute Wollongong New South Wales 2522 Australia
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11
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Corbella M, Toa ZSD, Scholes GD, Luque FJ, Curutchet C. Determination of the protonation preferences of bilin pigments in cryptophyte antenna complexes. Phys Chem Chem Phys 2018; 20:21404-21416. [PMID: 30105318 DOI: 10.1039/c8cp02541j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The light-harvesting mechanisms of cryptophyte antenna complexes have attracted considerable attention due to their ability to exhibit maximal photosynthetic activity under very low-light conditions and to display several colors, as well as the observation of vibronic coherent features in their two-dimensional electronic spectra. However, detailed investigations on the interplay between the protein environment and their light-harvesting properties are hampered by the uncertainty related to the protonation state of the underlying bilin pigments. Here we study the protonation preferences of four types of bilin pigments including 15,16-dihydrobiliverdin (DBV), phycoerythrobilin (PEB), phycocyanobilin (PCB) and mesobiliverdin (MBV), which are found in phycoerythrin PE545 and phycocyanin PC577, PC612, PC630 and PC645 complexes. We apply quantum chemical calculations coupled to continuum solvation calculations to predict the intrinsic acidity of bilins in aqueous solution, and then combine molecular dynamics simulations with empirical pKa estimates to investigate the impact of the local protein environment on the acidity of the pigments. We also report measurements of the absorption spectra of the five complexes in a wide range of pH in order to validate our simulations and investigate possible changes in the light harvesting properties of the complexes in the range of physiological pH found in the lumen (pH ∼ 5-7). The results suggest a pKa > 7 for DBV and MBV pigments in the α polypeptide chains of PE545 and PC630/PC645 complexes, which are not coordinated to a negatively charged amino acid. For the other PEB, DBV and PCB pigments, which interact with a Glu or Asp side chain, higher pKa values (pKa > 8) are estimated. Overall, the results support a preferential population of the fully protonated state for bilins in cryptophyte complexes under physiological conditions regardless of the specific type of pigment and local protein environment.
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Affiliation(s)
- Marina Corbella
- Departament de Farmàcia i Tecnologia Farmacèutica i Fisicoquímica and Institut de Química Teòrica i Computacional (IQTCUB), Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain.
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12
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Velazquez Escobar F, Utesch T, Narikawa R, Ikeuchi M, Mroginski MA, Gärtner W, Hildebrandt P. Photoconversion mechanism of the second GAF domain of cyanobacteriochrome AnPixJ and the cofactor structure of its green-absorbing state. Biochemistry 2013; 52:4871-80. [PMID: 23808413 DOI: 10.1021/bi400506a] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyanobacteriochromes are members of the phytochrome superfamily. In contrast to classical phytochromes, these small photosensors display a considerable variability of electronic absorption maxima. We have studied the light-induced conversions of the second GAF domain of AnPixJ, AnPixJg2, a phycocyanobilin-binding protein from the cyanobacterium Anabaena PCC 7120, using low-temperature resonance Raman spectroscopy combined with molecular dynamics simulations. AnPixJg2 is formed biosynthetically as a red-absorbing form (Pr) and can be photoconverted into a green-absorbing form (Pg). Forward and backward phototransformations involve the same reaction sequences and intermediates of similar cofactor structures as the corresponding processes in canonical phytochromes, including a transient cofactor deprotonation. Whereas the cofactor of the Pr state shows far-reaching similarities to the Pr states of classical phytochromes, the Pg form displays significant upshifts of the methine bridge stretching frequencies concomitant to the hypsochromically shifted absorption maximum. However, the cofactor in Pg is protonated and adopts a conformation very similar to the Pfr state of classical phytochromes. The spectral differences are probably related to an increased solvent accessibility of the chromophore which may reduce the π-electron delocalization in the phycocyanobilin and thus raise the energies of the first electronic transition and the methine bridge stretching modes. Molecular dynamics simulations suggest that the Z → E photoisomerization of the chromophore at the C-D methine bridge alters the interactions with the nearby Trp90 which in turn may act as a gate, allowing the influx of water molecules into the chromophore pocket. Such a mechanism of color tuning AnPixJg2 is unique among the cyanobacteriochromes studied so far.
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Affiliation(s)
- Francisco Velazquez Escobar
- Institut für Chemie, Technische Universität Berlin , Sekr. PC14, Straße des 17 Juni 135, D-10623 Berlin, Germany
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13
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Thomas DB, McGoverin CM, McGraw KJ, James HF, Madden O. Vibrational spectroscopic analyses of unique yellow feather pigments (spheniscins) in penguins. J R Soc Interface 2013; 10:20121065. [PMID: 23516063 DOI: 10.1098/rsif.2012.1065] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Many animals extract, synthesize and refine chemicals for colour display, where a range of compounds and structures can produce a diverse colour palette. Feather colours, for example, span the visible spectrum and mostly result from pigments in five chemical classes (carotenoids, melanins, porphyrins, psittacofulvins and metal oxides). However, the pigment that generates the yellow colour of penguin feathers appears to represent a sixth, poorly characterized class of feather pigments. This pigment class, here termed 'spheniscin', is displayed by half of the living penguin genera; the larger and richer colour displays of the pigment are highly attractive. Using Raman and mid-infrared spectroscopies, we analysed yellow feathers from two penguin species (king penguin, Aptenodytes patagonicus; macaroni penguin, Eudyptes chrysolophus) to further characterize spheniscin pigments. The Raman spectrum of spheniscin is distinct from spectra of other feather pigments and exhibits 17 distinctive spectral bands between 300 and 1700 cm(-1). Spectral bands from the yellow pigment are assigned to aromatically bound carbon atoms, and to skeletal modes in an aromatic, heterocyclic ring. It has been suggested that the penguin pigment is a pterin compound; Raman spectra from yellow penguin feathers are broadly consistent with previously reported pterin spectra, although we have not matched it to any known compound. Raman spectroscopy can provide a rapid and non-destructive method for surveying the distribution of different classes of feather pigments in the avian family tree, and for correlating the chemistry of spheniscin with compounds analysed elsewhere. We suggest that the sixth class of feather pigments may have evolved in a stem-lineage penguin and endowed modern penguins with a costly plumage trait that appears to be chemically unique among birds.
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Affiliation(s)
- Daniel B Thomas
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA.
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14
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Turner DB, Dinshaw R, Lee KK, Belsley MS, Wilk KE, Curmi PMG, Scholes GD. Quantitative investigations of quantum coherence for a light-harvesting protein at conditions simulating photosynthesis. Phys Chem Chem Phys 2012; 14:4857-74. [PMID: 22374579 DOI: 10.1039/c2cp23670b] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Recent measurements using two-dimensional electronic spectroscopy (2D ES) have shown that the initial dynamic response of photosynthetic proteins can involve quantum coherence. We show how electronic coherence can be differentiated from vibrational coherence in 2D ES. On that basis we conclude that both electronic and vibrational coherences are observed in the phycobiliprotein light-harvesting complex PC645 from Chroomonas sp. CCMP270 at ambient temperature. These light-harvesting antenna proteins of the cryptophyte algae are suspended in the lumen, where the pH drops significantly under sustained illumination by sunlight. Here we measured 2D ES of PC645 at increasing levels of acidity to determine if the change in pH affects the quantum coherence; quantitative analysis reveals that the dynamics are insensitive to the pH change.
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Affiliation(s)
- Daniel B Turner
- Department of Chemistry, Institute for Optical Sciences, and Centre for Quantum Information and Quantum Control, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
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15
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Elucidating photoinduced structural changes in phytochromes by the combined application of resonance Raman spectroscopy and theoretical methods. J Mol Struct 2011. [DOI: 10.1016/j.molstruc.2011.02.038] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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16
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Mroginski MA, Kaminski S, von Stetten D, Ringsdorf S, Gärtner W, Essen LO, Hildebrandt P. Structure of the chromophore binding pocket in the Pr state of plant phytochrome phyA. J Phys Chem B 2010; 115:1220-31. [PMID: 21192668 DOI: 10.1021/jp108265h] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A homology structural model was generated for plant phytochrome phyA utilizing the crystal structure of the sensory module of cyanobacterial phytochrome Cph1 (Cph1Δ2). As chromophores, either the native phytochromobilin cofactor (PΦB) or phycocyanobilin (PCB), the natural cofactor in Cph1, was incorporated. These homology models were further optimized by molecular dynamics (MD) simulations revealing a satisfying overall agreement with the crystal structure of Cph1Δ2. Notable differences in the PΦB adduct of phyA result from a restructuring of the small helical segment α(7) that leads to displacements of a few amino acids away from the cofactor. This repositioning of residues also include aspartate 218 such that, instead of its carbonyl function as in Cph1Δ2, an additional water molecule forms hydrogen bonds with the ring B and C NH groups. To validate the phyA structural model in the chromophore binding pocket, Raman spectra of the cofactor were calculated by means of the quantum mechanics/molecular mechanics (QM/MM) hybrid methodology and compared with the experimental resonance Raman (RR) spectra. The satisfactory overall agreement between calculated and experimental spectra is taken as an indication for the good quality of the structural model. Moreover, the methine bridge stretching modes and the effects of isotopic labeling at selected positions of the chromophore are very well reproduced to allow confirming even details of the methine bridge geometry as predicted by the homology model. Specifically, it is demonstrated that the experimental RR spectra are consistent with a torsional angle of ring D with respect to ring C that is distinctly higher for phyA-PCB (45°) and phyA-PΦB (42°) than for Cph1Δ2 (30°). Raman spectra calculated from different points of the MD trajectory display variations of the mode frequencies and intensities reflecting the structural fluctuations from snapshot to snapshot. The snapshot spectrum of the lowest energy structure and the sum of all snapshot spectra afford an equally good description of the experimental data. Particularly large variations between the snapshots are noted for the N-H in-plane bending mode of the pyrrole rings B and C, which reflect alterations of the hydrogen bond interactions brought about by fluctuations of water molecules in the cofactor cavity. This overestimation of the water molecule mobility is a consequence of the deficiency of the current QM/MM methodology that, due to the lack of appropriate protein force fields, cannot adequately account for the electrostatics in the cofactor pocket.
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17
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Mroginski MA, von Stetten D, Escobar FV, Strauss HM, Kaminski S, Scheerer P, Günther M, Murgida DH, Schmieder P, Bongards C, Gärtner W, Mailliet J, Hughes J, Essen LO, Hildebrandt P. Chromophore structure of cyanobacterial phytochrome Cph1 in the Pr state: reconciling structural and spectroscopic data by QM/MM calculations. Biophys J 2009; 96:4153-63. [PMID: 19450486 DOI: 10.1016/j.bpj.2009.02.029] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Revised: 01/21/2009] [Accepted: 02/05/2009] [Indexed: 10/20/2022] Open
Abstract
A quantum mechanics (QM)/molecular mechanics (MM) hybrid method was applied to the Pr state of the cyanobacterial phytochrome Cph1 to calculate the Raman spectra of the bound PCB cofactor. Two QM/MM models were derived from the atomic coordinates of the crystal structure. The models differed in the protonation site of His(260) in the chromophore-binding pocket such that either the delta-nitrogen (M-HSD) or the epsilon-nitrogen (M-HSE) carried a hydrogen. The optimized structures of the two models display small differences specifically in the orientation of His(260) with respect to the PCB cofactor and the hydrogen bond network at the cofactor-binding site. For both models, the calculated Raman spectra of the cofactor reveal a good overall agreement with the experimental resonance Raman (RR) spectra obtained from Cph1 in the crystalline state and in solution, including Cph1 adducts with isotopically labeled PCB. However, a distinctly better reproduction of important details in the experimental spectra is provided by the M-HSD model, which therefore may represent an improved structure of the cofactor site. Thus, QM/MM calculations of chromoproteins may allow for refining crystal structure models in the chromophore-binding pocket guided by the comparison with experimental RR spectra. Analysis of the calculated and experimental spectra also allowed us to identify and assign the modes that sensitively respond to chromophore-protein interactions. The most pronounced effect was noted for the stretching mode of the methine bridge A-B adjacent to the covalent attachment site of PCB. Due a distinct narrowing of the A-B methine bridge bond angle, this mode undergoes a large frequency upshift as compared with the spectrum obtained by QM calculations for the chromophore in vacuo. This protein-induced distortion of the PCB geometry is the main origin of a previous erroneous interpretation of the RR spectra based on QM calculations of the isolated cofactor.
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18
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Electronic Properties and Conformation Analysis of Phytochromobilins, Chromophore in Phytochrome. B KOREAN CHEM SOC 2008. [DOI: 10.5012/bkcs.2008.29.9.1678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Petrenko T, Neese F. Analysis and prediction of absorption band shapes, fluorescence band shapes, resonance Raman intensities, and excitation profiles using the time-dependent theory of electronic spectroscopy. J Chem Phys 2008; 127:164319. [PMID: 17979350 DOI: 10.1063/1.2770706] [Citation(s) in RCA: 211] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A general method for the simulation of absorption (ABS) and fluorescence band shapes, resonance-Raman (rR) spectra, and excitation profiles based on the time-dependent theory of Heller is discussed. The following improvements to Heller's theory have been made: (a) derivation of new recurrence relations for the time-dependent wave packet overlap in the case of frequency changes between the ground and electronically excited states, (b) a new series expansion that gives insight into the nature of Savin's preresonance approximation, (c) incorporation of inhomogeneous broadening effects into the formalism at no additional computational cost, and (d) derivation of a new and simple short-time dynamics based equation for the Stokes shift that remains valid in the case of partially resolved vibrational structure. Our implementation of the time-dependent theory for the fitting of experimental spectra and the simulation of model spectra as well as the quantum mechanical calculation of the model parameters is discussed. The implementation covers all electronic structure approaches which are able to deliver ground- and excited-state energies and transition dipole moments. The technique becomes highly efficient if analytic gradients for the excited-state surface are available. In this case, the computational cost for the simultaneous prediction of ABS, fluorescence, and rR spectra is equal to that of a single excited-state geometry optimization step while the limitations of the short-time dynamics approximation are completely avoided. As a test case we discuss the well-known case of the strongly allowed 1 (1)A(g) --> 1 (1)B(u) transition in 1,3,5 trans-hexatriene in detail using method ranging from simple single-reference treatments to elaborate multireference electronic structure approaches. At the highest computational level, the computed spectra show the best agreement that has so far been obtained with quantum chemical methods for this problem.
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Affiliation(s)
- Taras Petrenko
- Lehrstuhl für Theoretische Chemie, Universität Bonn, Wegelerstrasse 12, 53115 Bonn, Germany
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20
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van Thor JJ, Fisher N, Rich PR. Assignments of the Pfr-Pr FTIR difference spectrum of cyanobacterial phytochrome Cph1 using 15N and 13C isotopically labeled phycocyanobilin chromophore. J Phys Chem B 2007; 109:20597-604. [PMID: 16853666 DOI: 10.1021/jp052323t] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reversible red and far-red light-induced transitions of cyanobacterial phytochrome Cph1 from Synechocystis PCC 6803 were investigated by Fourier transform infrared (FTIR) difference spectroscopy. High-quality light-induced Pfr-Pr difference FTIR spectra were recorded for the 58 kDa N-terminal domain of Cph1 by repetitive photochemical cycling and signal averaging. The Pfr-Pr difference spectra in H(2)O and D(2)O were very similar to those previously reported for full-length 85 kDa Cph1.(1) Published assignments were extended by analysis of the effects of (13)C and (15)N isotope substitutions at selected sites in the phycocyanobilin chromophore and by (15)N global labeling of the protein. The Pfr-Pr difference spectra were dominated by an amide I peak/trough at 1653 cm(-1)(+)/1631 cm(-1)(-) and a smaller amide II band at 1554 cm(-1). Labeling effects allowed specific chromophore assignments for the C(1)=O (1736 cm(-1)(-)/1724 cm(-1)(+)) and C(19)=O (1704 cm(-1)(-)) carbonyl vibrations, C=C vibrations at 1589 cm(-1)(+), and bands at 1537(-), 1512(+), 1491(-), 1163(+), 1151(-), 1134(+), 1109(-), and 1072(-) cm(-1) that must involve chromophore C-N bonds. A variety of additional changes were insensitive to isotope labeling of the chromophore. Effects of (15)N labeling of the protein were used to tentatively assign some of these to specific amino acid changes. Those insensitive to (15)N labeling included a protonated aspartic or glutamic acid at 1734 cm(-1)(-)/1722 cm(-1)(+) and a cysteine at 2575 cm(-1)(+)/2557 cm(-1)(-). Bands sensitive to (15)N protein labeling at 1487 cm(-1)(+)/1502 cm(-1)(-) might arise from trytophan and bands at 1261 cm(-1)(+)/1244 cm(-1)(-) and 1107 cm(-1)(-)/1095 cm(-1)(+) might arise from a histidine environment or protonation change. These assignments are discussed in light of the 15Z-E photoisomerization model of phototransformation and the associated protein conformational changes.
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Affiliation(s)
- Jasper J van Thor
- Laboratory of Molecular Biophysics, Rex Richards Building, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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21
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Mroginski MA, Németh K, Bauschlicher T, Klotzbücher W, Goddard R, Heinemann O, Hildebrandt P, Mark F. Calculation of vibrational spectra of linear tetrapyrroles. 3. Hydrogen-bonded hexamethylpyrromethene dimers. J Phys Chem A 2007; 109:2139-50. [PMID: 16838985 DOI: 10.1021/jp045805y] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structure and vibrational spectra of hexamethylpyrromethene (HMPM) have been investigated by X-ray crystallography, IR and Raman spectroscopies, and density functional theory calculations. HMPM crystallizes in the form of dimers, which are held together by bifurcated N-H(...N)(2) hydrogen bonds, involving one intramolecular and one intermolecular N-H...N interaction. The monomers are essentially planar, and the mean planes of the monomers lie approximately perpendicular to one another, so that the four N atoms in the dimer form a distorted tetrahedron. The structure of the HMPM dimer is well-reproduced by B3LYP/6-31G calculations. A comparison of the calculated geometry of the dimer with that of the monomer reveals only small changes in the N-H...N entity and the methine bridge angles upon dimerization. These are a result of weakening of the intramolecular N-H...N hydrogen bond and the formation of a more linear N-H...N intermolecular hydrogen bond. Using an empirical relation between the shift of the N-H stretching frequency of pyrrole and the enthalpy of adduct formation with bases [Nozari, M. S.; Drago, R. S. J. Am. Chem. Soc. 1970, 92, 7086-7090], estimates of the strength of the intra- and intermolecular hydrogen bonds are obtained. IR and Raman spectroscopies of HMPM and its isotopomers deuterated at the pyrrolic nitrogen atom and at the methine bridge reveal that the molecule is monomeric in nonpolar organic solvents but dimeric in a solid Ar matrix and in KBr pellets. The matrix IR spectra show a splitting of vibrational modes for the dimer, particularly those involving the N-H coordinates. Due to intrinsic deficiencies of the B3LYP/6-31G approximation, a satisfactory reproduction of these modes of the monomeric and dimeric HMPM requires specific adjustments of the NH scaling factors for the calculated force constants and, in the case of the NH out-of-plane modes of HMPM dimers, also of intra- and intermolecular coupling constants. This parametrization does not significantly affect the other calculated modes, which in general reveal a very good agreement with the experimental data.
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Affiliation(s)
- Maria-Andrea Mroginski
- Max-Volmer-Laboratorium, Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17 Juni 135, D-10623 Berlin, Germany
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22
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Mroginski MA, Mark F, Thiel W, Hildebrandt P. Quantum mechanics/molecular mechanics calculation of the Raman spectra of the phycocyanobilin chromophore in alpha-C-phycocyanin. Biophys J 2007; 93:1885-94. [PMID: 17513350 PMCID: PMC1959556 DOI: 10.1529/biophysj.107.108878] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have established a quantum mechanics (QM)/molecular mechanics (MM) hybrid method for calculating the Raman spectra of protein-bound cofactors using the alpha-subunit of C-phycocyanin containing a phycocyanobilin (PCB) chromophore as a test case. The PCB cofactor was described with density functional theory, whereas the protein matrix was treated with the CHARMM force field. The Hessian matrix of the QM region was built by taking into account bonded and nonbonded interactions with the protein environment and projected onto the internal coordinate space. Force constants were scaled with a global set of scaling factors, and the Raman intensities were computed using a finite-field method combined with a fourth-order differentiation algorithm for the calculation of the polarizability derivatives. In general, the QM/MM results provided a substantially improved description of the experimental resonance Raman (RR) spectra of the protein-bound cofactor compared to QM calculations of isolated PCB models in vacuo. The results allow the assessment of the effect of the protein-cofactor interactions on the RR spectra and reveal the potential and limitations of QM calculations on isolated tetrapyrroles for determining the chromophore structures in the various species and states of phytochromes for which three-dimensional structures are not available.
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Affiliation(s)
- Maria Andrea Mroginski
- Technische Universität Berlin, Institut für Chemie, Max-Volmer-Laboratorium für Biophysikalische Chemie, Sekr. PC 14, D-10623 Berlin, Germany.
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23
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Mroginski MA, Murgida DH, Hildebrandt P. The chromophore structural changes during the photocycle of phytochrome: a combined resonance Raman and quantum chemical approach. Acc Chem Res 2007; 40:258-66. [PMID: 17279729 DOI: 10.1021/ar6000523] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phytochromes are sensory photoreceptors that, upon light irradiation, can be transformed between an inactive and an active state. The conversion is initiated by the photoisomerization of the cofactor, a linear methine-bridged tetrapyrrole, followed by conformational relaxations of the chromophore and the protein matrix that finally leads to the formation of the signaling state. To elucidate the underlying molecular processes, resonance Raman spectroscopy combined with quantum chemical calculations constitutes a powerful approach since it allows determination of the chromophore structure in the various states of phytochrome. On the basis of these studies, a molecular model for the photoinduced reaction cycle is derived.
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Affiliation(s)
- Maria Andrea Mroginski
- Technische Universität Berlin, Institut für Chemie, Max-Volmer-Laboratorium für Biophysikalische Chemie, Sekr. PC 14, Strasse des 17, Juni 135, D-10623 Berlin, Germany.
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24
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Neese F, Petrenko T, Ganyushin D, Olbrich G. Advanced aspects of ab initio theoretical optical spectroscopy of transition metal complexes: Multiplets, spin-orbit coupling and resonance Raman intensities. Coord Chem Rev 2007. [DOI: 10.1016/j.ccr.2006.05.019] [Citation(s) in RCA: 253] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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25
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Mroginski MA, Murgida DH, Hildebrandt P. Calculation of Vibrational Spectra of Linear Tetrapyrroles. 4. Methine Bridge C−H Out-of-Plane Modes. J Phys Chem A 2006; 110:10564-74. [PMID: 16956238 DOI: 10.1021/jp063128x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quantum chemical force fields obtained by density functional theory (DFT) calculations systematically overestimate the frequencies of normal modes including ethylenic C-H out-of-plane (HOOP) coordinates. Compensation of this deviation requires a specific scaling factor for this type of coordinate that is distinctly lower than those applicable to out-of-plane coordinates in general. Such a specific scaling factor (0.900) has been optimized for the DFT(B3LYP) level of theory on the basis of vibrational analyses of training molecules including the HOOP coordinate. Thus, the root-mean-square deviation for the calculated frequencies of these modes is reduced from 16 to 8 cm(-1). Although Raman intensities are yet not reproduced in a satisfactory manner, implementation of the HOOP scaling factor into the set of global scaling factors determined previously (Magdo et al. J. Phys. Chem. A 1999, 103, 289-303) allows for a substantially improved reproduction of the experimental (resonance) Raman spectra of test molecules including linear methine-bridged tetrapyrroles. A very good agreement between calculated and experimental spectra is noted for the phycocyanobilin dimethylester dimer as well as for the protein-bound phycocyanobilin in the antenna pigment alpha-CPC. However, for the phycocyanobilin chromophore in the P(r) state of the plant photoreceptor phytochrome phyA, considerable deviations remain in the spectral range between 800 and 500 cm(-1), which are attributed to the effect of specific protein-chromophore interactions. The influence of the protein environment is not considered in the present calculations that refer to the molecule in vacuo.
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Affiliation(s)
- Maria Andrea Mroginski
- Technische Universität Berlin, Institut für Chemie, Max-Volmer-Laboratorium, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany.
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26
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Borucki B. Proton transfer in the photoreceptors phytochrome and photoactive yellow protein. Photochem Photobiol Sci 2006; 5:553-66. [PMID: 16761084 DOI: 10.1039/b603846h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Light-induced activation of the photoreceptors phytochrome and photoactive yellow protein (PYP) is accompanied by protonation changes of the respective chromophores and key residues in the protein moiety. For both systems, proton exchange with the external medium could be observed with pH electrode measurements and with UV-visible absorption spectroscopy using appropriate pH indicator dyes. From these signals, the stoichiometry of proton release and uptake, respectively, was determined by different calibration procedures which will be presented and discussed. Kinetic information on these processes is only available from time-resolved measurements with pH indicator dyes. Vibrational spectroscopy methods such as Fourier transform infrared spectroscopy and resonance Raman scattering provided information on the protonation state of individual functional groups suggesting that internal proton transfer processes are involved as well. Deuterium kinetic isotope effects that occurred in the Pr --> Pfr phototransformation of the bacteriophytochromes Cph1 and Agp1 were consistent with proton transfer reactions as rate-limiting steps. In contrast, the apparent rate constants in the photocycle of PYP exhibited only small kinetic isotope effects that could not be interpreted conclusively. Possible mechanisms of proton transfer in the activation of phytochrome and PYP will be discussed.
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Affiliation(s)
- Berthold Borucki
- Biophysics Group, Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
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27
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Mroginski MA, Murgida DH, von Stetten D, Kneip C, Mark F, Hildebrandt P. Determination of the Chromophore Structures in the Photoinduced Reaction Cycle of Phytochrome. J Am Chem Soc 2004; 126:16734-5. [PMID: 15612706 DOI: 10.1021/ja043959l] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The chromophore structures in the parent states Pr and Pfr as well as in the photocycle intermediate Lumi-R of oat phytochrome phyA are determined by comparison of the experimental resonance Raman spectra with calculated Raman spectra that have been obtained by density functional theory calculations (B3LYP) using scaled force fields. The spectra were calculated for various tetrapyrrole geometries including more than twenty different methine bridge isomers. For the parent states Pr and Pfr the best agreement in terms of vibrational frequencies, isotopic shifts, and Raman intensities was achieved with the ZZZasa and ZZEssa geometry, respectively. For the first intermediate Lumi-R, the chromophore geometry is concluded to be the ZZEasa configuration. These finding imply that the primary step of the photoactivation of phytochrome is the Z/E isomerization of the C-D methine bridge double bond, whereas the single bond remains in the anti conformation. The subsequent transition to the physiologically active state Pfr includes a (partial) single bond rotation of the A-B methine bridge.
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Affiliation(s)
- Maria Andrea Mroginski
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany
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Göller AH, Strehlow D, Hermann G. Conformational Flexibility of Phycocyanobilin: An AM1 Semiempirical Study. Chemphyschem 2001; 2:665-71. [DOI: 10.1002/1439-7641(20011119)2:11<665::aid-cphc665>3.0.co;2-o] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2001] [Indexed: 11/07/2022]
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29
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Kneip C, Schlamann W, Braslavsky SE, Hildebrandt P, Schaffner K. Resonance Raman spectroscopic study of the tryptic 39-kDa fragment of phytochrome. FEBS Lett 2000; 482:252-6. [PMID: 11024470 DOI: 10.1016/s0014-5793(00)02069-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The 39-kDa fragment of oat phytochrome phyA, obtained by tryptic digestion at the amino acids 65 and 425, was studied by resonance Raman spectroscopy. The parent state P(r) reveals far-reaching similarities with that of the native phytochrome implying that the structures of the tetrapyrrole chromophore and its immediate protein environment are not affected by the proteolysis. However, the resonance Raman spectrum of the final product of the P(r) phototransformation, denoted as P(bl), is more closely related to that of the P(fr) precursor of the native phytochrome, i.e. meta-R(C), rather than to that of P(fr) itself. The resonance Raman spectra indicate a high conformational flexibility of the chromophore in P(bl) so that, unlike in P(fr), the tetrapyrrole rings C and D adopt a largely coplanar conformation. The protein interactions with ring D of the chromophore, which in the native phytochrome stabilize the specific chromophore structure of P(fr), cannot be established in the 39-kDa fragment due to the lack of the major C-terminal part of the protein. These findings, furthermore, support the view that the meta-R(C)-->P(fr) transition is associated with a coupling of chromophore and protein structural changes that represent crucial events for the photoactivation of phytochrome.
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Affiliation(s)
- C Kneip
- Max-Planck-Institut für Strahlenchemie, Postfach 101365, D-45413, Mülheim, Germany
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30
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Mroginski MA, Németh K, Magdó I, Müller M, Robben U, Della Védova C, Hildebrandt P, Mark F. Calculation of the Vibrational Spectra of Linear Tetrapyrroles. 2. Resonance Raman Spectra of Hexamethylpyrromethene Monomers. J Phys Chem B 2000. [DOI: 10.1021/jp000444h] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Maria-Andrea Mroginski
- Max-Planck-Institut für Strahlenchemie, Postfach 101365, D-45413 Mülheim a.d. Ruhr, Germany, and Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, 1900 La Plata, Argentina
| | - Károly Németh
- Max-Planck-Institut für Strahlenchemie, Postfach 101365, D-45413 Mülheim a.d. Ruhr, Germany, and Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, 1900 La Plata, Argentina
| | - Ildikó Magdó
- Max-Planck-Institut für Strahlenchemie, Postfach 101365, D-45413 Mülheim a.d. Ruhr, Germany, and Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, 1900 La Plata, Argentina
| | - Martin Müller
- Max-Planck-Institut für Strahlenchemie, Postfach 101365, D-45413 Mülheim a.d. Ruhr, Germany, and Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, 1900 La Plata, Argentina
| | - Uwe Robben
- Max-Planck-Institut für Strahlenchemie, Postfach 101365, D-45413 Mülheim a.d. Ruhr, Germany, and Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, 1900 La Plata, Argentina
| | - Carlos Della Védova
- Max-Planck-Institut für Strahlenchemie, Postfach 101365, D-45413 Mülheim a.d. Ruhr, Germany, and Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, 1900 La Plata, Argentina
| | - Peter Hildebrandt
- Max-Planck-Institut für Strahlenchemie, Postfach 101365, D-45413 Mülheim a.d. Ruhr, Germany, and Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, 1900 La Plata, Argentina
| | - Franz Mark
- Max-Planck-Institut für Strahlenchemie, Postfach 101365, D-45413 Mülheim a.d. Ruhr, Germany, and Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, 1900 La Plata, Argentina
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Abstract
Vibrational spectroscopy has become increasingly important as a tool for understanding the mechanisms of photosystem II, phytochrome and terminal oxidases. More general enzymatic or receptor systems have been studied, opening a new field of applications. Femtosecond infrared pump/probe studies of the important amide-I band seem to provide a basis for its molecular and structural interpretation.
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Affiliation(s)
- R Vogel
- Sektion Biophysik, Institut für Molekulare Medizin und Zellforschung, Albert-Ludwigs-Universität, Albertstrasse 23, D-79104 Freiburg, Germany.
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Kneip C, Hildebrandt P, Schlamann W, Braslavsky SE, Mark F, Schaffner K. Protonation state and structural changes of the tetrapyrrole chromophore during the Pr --> Pfr phototransformation of phytochrome: a resonance Raman spectroscopic study. Biochemistry 1999; 38:15185-92. [PMID: 10563801 DOI: 10.1021/bi990688w] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The photoconversion of phytochrome (phytochrome A from Avena satina) from the inactive (Pr) to the physiologically active form (Pfr) was studied by near-infrared Fourier transform resonance Raman spectroscopy at cryogenic temperatures, which allow us to trap the intermediate states. Nondeuterated and deuterated buffer solutions were used to determine the effect of H/D exchange on the resonance Raman spectra. For the first time, reliable spectra of the "bleached" intermediates meta-R(A) and meta-R(C) were obtained. The vibrational bands in the region 1300-1700 cm(-)(1), which is particularly indicative of structural changes in tetrapyrroles, were assigned on the basis of recent calculations of the Raman spectra of the chromophore in C-phycocyanin and model compounds [Kneip, C., Hildebrandt, P., Németh, K., Mark, F., Schaffner, K. (1999) Chem. Phys. Lett. 311, 479-485]. The experimental resonance Raman spectra Pr are compatible with the Raman spectra calculated for the protonated ZZZasa configuration, which hence is suggested to be the chromophore structure in this parent state of phytochrome. Furthermore, marker bands could be identified that are of high diagnostic value for monitoring structural changes in individual parts of the chromophore. Specifically, it could be shown that not only in the parent states Pr and Pfr but also in all intermediates the chromophore is protonated at the pyrroleninic nitrogen. The spectral changes observed for lumi-R confirm the view that the photoreaction of Pr is a Z --> E isomerization of the CD methine bridge. The subsequent thermal decay reaction to meta-R(A) includes relaxations of the CD methine bridge double bond, whereas the formation of meta-R(C) is accompanied by structural adaptations of the pyrrole rings B and C in the protein pocket. The far-reaching similarities between the chromophores of meta-R(A) and Pfr suggest that in the step meta-R(A) --> Pfr the ultimate structural changes of the protein matrix occur.
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Affiliation(s)
- C Kneip
- Max-Planck-Institut für Strahlenchemie, Mülheim an der Ruhr, Germany
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