Studying photosynthetic antenna complexes in vivo and in vitro using time-resolved fluorescence spectroscopy

Reza Ranjbar Choubeh

Research output: Thesisinternal PhD, WU

Abstract

In this thesis, I used time-resolved fluorescence spectroscopy to study regulation of excitation energy transfer (EET) and photoprotection in cyanobacteria and the green sulfur bacterium Chlorobaculum tepidum.

Chapter 1 provides a general introduction for the rest of the thesis.

Chapter 2 describes the study of EET in APC trimers, which are part of the antenna of cyanobacteria in crystal and functional forms. It is concluded that the same protein has at least two different structures in APC trimers and that the structure of APC trimers in crystal form deviates to some extent from the structure of APC in protein solution.

Chapter 3 presents the study of state transitions in the cyanobacterium Synechococcus elongatus 7942. It is concluded that in state II photosystem II (PSII) is quenched and the spill-over of excitation energy from PSII to PSI is not involved in state transitions. It is also shown that in state I some of the phycobilisomes (PBSs) detach from both photosystems.

Chapter 4 presents a model of photoprotection in the cyanobacterium Leptolyngbya ohadii, which is normally living in the desert. In the desiccated state, excitation energy in the PBS is severely quenched as compared to the hydrated state. It is concluded that the quenching is due to the loss of the organized structure of PC rods in the dry state.

Chapter 5 present the study of EET in the green sulfur bacterium C. tepidum. It is demonstrated that the efficiency of EET does not depend significantly on the temperature and that the time scale of excitation energy trapping in the reaction centers is comparable with other much smaller photosynthetic systems such as that of cyanobacteria.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • van Amerongen, Herbert, Promotor
  • Struik, Paul, Promotor
Award date19 Nov 2018
Place of PublicationWageningen
Publisher
Print ISBNs9789463434959
DOIs
Publication statusPublished - 2018

Fingerprint

Excitation energy
Fluorescence spectroscopy
Antennas
Energy transfer
Photosystem II Protein Complex
Sulfur
Bacteria
Crystals
Hazardous materials spills
Quenching
Proteins
Cyanobacteria

Cite this

Ranjbar Choubeh, Reza. / Studying photosynthetic antenna complexes in vivo and in vitro using time-resolved fluorescence spectroscopy. Wageningen : Wageningen University, 2018. 182 p.
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abstract = "In this thesis, I used time-resolved fluorescence spectroscopy to study regulation of excitation energy transfer (EET) and photoprotection in cyanobacteria and the green sulfur bacterium Chlorobaculum tepidum. Chapter 1 provides a general introduction for the rest of the thesis. Chapter 2 describes the study of EET in APC trimers, which are part of the antenna of cyanobacteria in crystal and functional forms. It is concluded that the same protein has at least two different structures in APC trimers and that the structure of APC trimers in crystal form deviates to some extent from the structure of APC in protein solution. Chapter 3 presents the study of state transitions in the cyanobacterium Synechococcus elongatus 7942. It is concluded that in state II photosystem II (PSII) is quenched and the spill-over of excitation energy from PSII to PSI is not involved in state transitions. It is also shown that in state I some of the phycobilisomes (PBSs) detach from both photosystems. Chapter 4 presents a model of photoprotection in the cyanobacterium Leptolyngbya ohadii, which is normally living in the desert. In the desiccated state, excitation energy in the PBS is severely quenched as compared to the hydrated state. It is concluded that the quenching is due to the loss of the organized structure of PC rods in the dry state. Chapter 5 present the study of EET in the green sulfur bacterium C. tepidum. It is demonstrated that the efficiency of EET does not depend significantly on the temperature and that the time scale of excitation energy trapping in the reaction centers is comparable with other much smaller photosynthetic systems such as that of cyanobacteria.",
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Studying photosynthetic antenna complexes in vivo and in vitro using time-resolved fluorescence spectroscopy. / Ranjbar Choubeh, Reza.

Wageningen : Wageningen University, 2018. 182 p.

Research output: Thesisinternal PhD, WU

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T1 - Studying photosynthetic antenna complexes in vivo and in vitro using time-resolved fluorescence spectroscopy

AU - Ranjbar Choubeh, Reza

N1 - WU thesis 7094 Includes bibliographical references. - With summary in English

PY - 2018

Y1 - 2018

N2 - In this thesis, I used time-resolved fluorescence spectroscopy to study regulation of excitation energy transfer (EET) and photoprotection in cyanobacteria and the green sulfur bacterium Chlorobaculum tepidum. Chapter 1 provides a general introduction for the rest of the thesis. Chapter 2 describes the study of EET in APC trimers, which are part of the antenna of cyanobacteria in crystal and functional forms. It is concluded that the same protein has at least two different structures in APC trimers and that the structure of APC trimers in crystal form deviates to some extent from the structure of APC in protein solution. Chapter 3 presents the study of state transitions in the cyanobacterium Synechococcus elongatus 7942. It is concluded that in state II photosystem II (PSII) is quenched and the spill-over of excitation energy from PSII to PSI is not involved in state transitions. It is also shown that in state I some of the phycobilisomes (PBSs) detach from both photosystems. Chapter 4 presents a model of photoprotection in the cyanobacterium Leptolyngbya ohadii, which is normally living in the desert. In the desiccated state, excitation energy in the PBS is severely quenched as compared to the hydrated state. It is concluded that the quenching is due to the loss of the organized structure of PC rods in the dry state. Chapter 5 present the study of EET in the green sulfur bacterium C. tepidum. It is demonstrated that the efficiency of EET does not depend significantly on the temperature and that the time scale of excitation energy trapping in the reaction centers is comparable with other much smaller photosynthetic systems such as that of cyanobacteria.

AB - In this thesis, I used time-resolved fluorescence spectroscopy to study regulation of excitation energy transfer (EET) and photoprotection in cyanobacteria and the green sulfur bacterium Chlorobaculum tepidum. Chapter 1 provides a general introduction for the rest of the thesis. Chapter 2 describes the study of EET in APC trimers, which are part of the antenna of cyanobacteria in crystal and functional forms. It is concluded that the same protein has at least two different structures in APC trimers and that the structure of APC trimers in crystal form deviates to some extent from the structure of APC in protein solution. Chapter 3 presents the study of state transitions in the cyanobacterium Synechococcus elongatus 7942. It is concluded that in state II photosystem II (PSII) is quenched and the spill-over of excitation energy from PSII to PSI is not involved in state transitions. It is also shown that in state I some of the phycobilisomes (PBSs) detach from both photosystems. Chapter 4 presents a model of photoprotection in the cyanobacterium Leptolyngbya ohadii, which is normally living in the desert. In the desiccated state, excitation energy in the PBS is severely quenched as compared to the hydrated state. It is concluded that the quenching is due to the loss of the organized structure of PC rods in the dry state. Chapter 5 present the study of EET in the green sulfur bacterium C. tepidum. It is demonstrated that the efficiency of EET does not depend significantly on the temperature and that the time scale of excitation energy trapping in the reaction centers is comparable with other much smaller photosynthetic systems such as that of cyanobacteria.

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