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Assefa GT, Botha JL, van Heerden B, Kyeyune F, Krüger TPJ, Gwizdala M. ApcE plays an important role in light-induced excitation energy dissipation in the Synechocystis PCC6803 phycobilisomes. PHOTOSYNTHESIS RESEARCH 2024; 160:17-29. [PMID: 38407779 PMCID: PMC11006782 DOI: 10.1007/s11120-024-01078-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 01/18/2024] [Indexed: 02/27/2024]
Abstract
Phycobilisomes (PBs) play an important role in cyanobacterial photosynthesis. They capture light and transfer excitation energy to the photosynthetic reaction centres. PBs are also central to some photoprotective and photoregulatory mechanisms that help sustain photosynthesis under non-optimal conditions. Amongst the mechanisms involved in excitation energy dissipation that are activated in response to excessive illumination is a recently discovered light-induced mechanism that is intrinsic to PBs and has been the least studied. Here, we used single-molecule spectroscopy and developed robust data analysis methods to explore the role of a terminal emitter subunit, ApcE, in this intrinsic, light-induced mechanism. We isolated the PBs from WT Synechocystis PCC 6803 as well as from the ApcE-C190S mutant of this strain and compared the dynamics of their fluorescence emission. PBs isolated from the mutant (i.e., ApcE-C190S-PBs), despite not binding some of the red-shifted pigments in the complex, showed similar global emission dynamics to WT-PBs. However, a detailed analysis of dynamics in the core revealed that the ApcE-C190S-PBs are less likely than WT-PBs to enter quenched states under illumination but still fully capable of doing so. This result points to an important but not exclusive role of the ApcE pigments in the light-induced intrinsic excitation energy dissipation mechanism in PBs.
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Affiliation(s)
- Gonfa Tesfaye Assefa
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
| | - Joshua L Botha
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
| | - Bertus van Heerden
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
- National Institute for Theoretical and Computational Sciences (NITheCS), Stellenbosch, South Africa
| | - Farooq Kyeyune
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
- Department of Physics, Faculty of Science, Kyambogo University, P.O. Box 1, Kyambogo, Kampala, Uganda
| | - Tjaart P J Krüger
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
- National Institute for Theoretical and Computational Sciences (NITheCS), Stellenbosch, South Africa
| | - Michal Gwizdala
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa.
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa.
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, 08860, Spain.
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Löhner A, Cogdell R, Köhler J. Contribution of low-temperature single-molecule techniques to structural issues of pigment-protein complexes from photosynthetic purple bacteria. J R Soc Interface 2018; 15:rsif.2017.0680. [PMID: 29321265 DOI: 10.1098/rsif.2017.0680] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 12/01/2017] [Indexed: 11/12/2022] Open
Abstract
As the electronic energies of the chromophores in a pigment-protein complex are imposed by the geometrical structure of the protein, this allows the spectral information obtained to be compared with predictions derived from structural models. Thereby, the single-molecule approach is particularly suited for the elucidation of specific, distinctive spectral features that are key for a particular model structure, and that would not be observable in ensemble-averaged spectra due to the heterogeneity of the biological objects. In this concise review, we illustrate with the example of the light-harvesting complexes from photosynthetic purple bacteria how results from low-temperature single-molecule spectroscopy can be used to discriminate between different structural models. Thereby the low-temperature approach provides two advantages: (i) owing to the negligible photobleaching, very long observation times become possible, and more importantly, (ii) at cryogenic temperatures, vibrational degrees of freedom are frozen out, leading to sharper spectral features and in turn to better resolved spectra.
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Affiliation(s)
- Alexander Löhner
- Spectroscopy of Soft Matter, University of Bayreuth, 95440 Bayreuth, Germany
| | - Richard Cogdell
- Institute of Molecular, Cell and Systems Biology, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland
| | - Jürgen Köhler
- Spectroscopy of Soft Matter, University of Bayreuth, 95440 Bayreuth, Germany .,Bayreuth Institute for Macromolecular Research (BIMF), University of Bayreuth, 95440 Bayreuth, Germany
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Kell A, Jassas M, Hacking K, Cogdell RJ, Jankowiak R. On Light-Induced Photoconversion of B800 Bacteriochlorophylls in the LH2 Antenna of the Purple Sulfur Bacterium Allochromatium vinosum. J Phys Chem B 2017; 121:9999-10006. [DOI: 10.1021/acs.jpcb.7b06185] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Kirsty Hacking
- Institute
of Molecular, Cell and Systems Biology, College of Medical, Veterinary
and Life Sciences, University of Glasgow, Glasgow G12 8TA, Scotland
| | - Richard J. Cogdell
- Institute
of Molecular, Cell and Systems Biology, College of Medical, Veterinary
and Life Sciences, University of Glasgow, Glasgow G12 8TA, Scotland
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4
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Stability and properties of quasi-stable conformational states in the LH2 light-harvesting complex of Rbl. acidophilus bacteria formed by hexacoordination of bacteriochlorophyll a magnesium atom. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2017.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Kondo T, Chen WJ, Schlau-Cohen GS. Single-Molecule Fluorescence Spectroscopy of Photosynthetic Systems. Chem Rev 2017; 117:860-898. [DOI: 10.1021/acs.chemrev.6b00195] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Toru Kondo
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge Massachusetts 02139, United States
| | - Wei Jia Chen
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge Massachusetts 02139, United States
| | - Gabriela S. Schlau-Cohen
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge Massachusetts 02139, United States
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Wientjes E, Renger J, Cogdell R, van Hulst NF. Pushing the Photon Limit: Nanoantennas Increase Maximal Photon Stream and Total Photon Number. J Phys Chem Lett 2016; 7:1604-9. [PMID: 27082249 PMCID: PMC4864408 DOI: 10.1021/acs.jpclett.6b00491] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 04/15/2016] [Indexed: 05/22/2023]
Abstract
Nanoantennas are well-known for their effective role in fluorescence enhancement, both in excitation and emission. Enhancements of 3-4 orders of magnitude have been reported. Yet in practice, the photon emission is limited by saturation due to the time that a molecule spends in singlet and especially triplet excited states. The maximal photon stream restricts the attainable enhancement. Furthermore, the total number of photons emitted is limited by photobleaching. The limited brightness and observation time are a drawback for applications, especially in biology. Here we challenge this photon limit, showing that nanoantennas can actually increase both saturation intensity and photostability. So far, this limit-shifting role of nanoantennas has hardly been explored. Specifically, we demonstrate that single light-harvesting complexes, under saturating excitation conditions, show over a 50-fold antenna-enhanced photon emission stream, with 10-fold more total photons, up to 10(8) detected photons, before photobleaching. This work shows yet another facet of the great potential of nanoantennas in the world of single-molecule biology.
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Affiliation(s)
- Emilie Wientjes
- ICFO − Institut de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- Laboratory of Biophysics, Wageningen University, 6703 HA Wageningen, The Netherlands
| | - Jan Renger
- ICFO − Institut de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- Max Planck Institute for the Science of
Light, D-91058 Erlangen, Germany
| | - Richard Cogdell
- Glasgow Biomedical Research
Building, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, U.K.
| | - Niek F. van Hulst
- ICFO − Institut de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- ICREA
− Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
- E-mail:
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