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The Plant Journal : For Cell and... May 2024CpcL-phycobilisomes (CpcL-PBSs) are a reduced type of phycobilisome (PBS) found in several cyanobacteria. They lack the traditional PBS terminal energy emitters, but...
CpcL-phycobilisomes (CpcL-PBSs) are a reduced type of phycobilisome (PBS) found in several cyanobacteria. They lack the traditional PBS terminal energy emitters, but still show the characteristic red-shifted fluorescence at ~670 nm. We established a method of assembling in vitro a rod-membrane linker protein, CpcL, with phycocyanin, generating complexes with the red-shifted spectral features of CpcL-PBSs. The red-shift arises from the interaction of a conserved key glutamine, Q57 of CpcL in Synechocystis sp. PCC 6803, with a single phycocyanobilin chromophore of trimeric phycocyanin at one of the three β82-sites. This chromophore is the terminal energy acceptor of CpcL-PBSs and donor to the photosystem(s). This mechanism also operates in PBSs from Acaryochloris marina MBIC11017. We then generated multichromic complexes harvesting light over nearly the complete visible range via the replacement of phycocyanobilin chromophores at sites α84 and β153 of phycocyanins by phycoerythrobilin and/or phycourobilin. The results demonstrate the rational design of biliprotein-based light-harvesting elements by engineering CpcL and phycocyanins, which broadens the light-harvesting range and accordingly improves the light-harvesting capacity and may be potentially applied in solar energy harvesting.
Topics: Phycobilisomes; Phycocyanin; Synechocystis; Bacterial Proteins; Phycobilins; Cyanobacteria
PubMed: 38319793
DOI: 10.1111/tpj.16666 -
Biomolecules Dec 2021Increasing evidence has revealed that the enzymes of several biological pathways assemble into larger supramolecular structures called super-complexes. Indeed, those... (Review)
Review
Increasing evidence has revealed that the enzymes of several biological pathways assemble into larger supramolecular structures called super-complexes. Indeed, those such as association of the mitochondrial respiratory chain complexes play an essential role in respiratory activity and promote metabolic fitness. Dynamically assembled super-complexes are able to alternate between participating in large complexes and existing in a free state. However, the functional significance of the super-complexes is not entirely clear. It has been proposed that the organization of respiratory enzymes into super-complexes could reduce oxidative damage and increase metabolism efficiency. There are several protein complexes that have been revealed in the plant chloroplast, yet little research has been focused on the formation of super-complexes in this organelle. The photosystem I and light-harvesting complex I super-complex's structure suggests that energy absorbed by light-harvesting complex I could be efficiently transferred to the PSI core by avoiding concentration quenching. Here, we will discuss in detail core complexes of photosystem I and II, the chloroplast ATPase the chloroplast electron transport chain, the Calvin-Benson cycle and a plastid localized purinosome. In addition, we will also describe the methods to identify these complexes.
Topics: Chloroplasts; Photosynthesis; Photosynthetic Reaction Center Complex Proteins; Photosystem I Protein Complex; Photosystem II Protein Complex; Plant Proteins; Plants
PubMed: 34944483
DOI: 10.3390/biom11121839 -
Photosynthesis Research Sep 2023I provide here both my personal and scientific autobiography. After giving a background and summary of most of my research, I present information on my parents, my...
I provide here both my personal and scientific autobiography. After giving a background and summary of most of my research, I present information on my parents, my childhood, schooling, university education, and postdoctoral research, all in Australia. This is followed by a presentation of my life and research in Cambridge, UK and then at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), in Australia, since 1955, where most of my research was done, especially on photosynthesis which included the following areas: Purification of a protochlorophyllide-protein complex; separation of the photochemical systems of photosynthesis; development of photochemical activity in photosynthesis; protein synthesis in plants; comparative photosynthesis of sun and shade plants; role of chlorophyll b in photosynthesis; photochemical properties of C4 plants; molecular interaction of thylakoid membranes; electron transport and ATP formation; and solar energy conversion in photosynthesis. In addition to research on the basics and applications of photosynthesis, I also mention at the end my service as a member of the executive of CSIRO.
Topics: Humans; Child; Photosynthesis; Chlorophyll; Electron Transport; Thylakoids; Sunlight; Plants
PubMed: 37155083
DOI: 10.1007/s11120-023-01021-1 -
Photosynthesis Research May 2022
Topics: Models, Molecular; Photosystem II Protein Complex
PubMed: 35761114
DOI: 10.1007/s11120-022-00930-x -
Journal of Plant Research Jul 2022
Topics: Chlorophyll; Electron Transport; Electrons; Kinetics; Light; Oxidation-Reduction; Photosynthesis; Photosystem I Protein Complex
PubMed: 35727481
DOI: 10.1007/s10265-022-01402-y -
Molecules (Basel, Switzerland) Jun 2021Chlorophylls and bacteriochlorophylls, together with carotenoids, serve, noncovalently bound to specific apoproteins, as principal light-harvesting and... (Review)
Review
Chlorophylls and bacteriochlorophylls, together with carotenoids, serve, noncovalently bound to specific apoproteins, as principal light-harvesting and energy-transforming pigments in photosynthetic organisms. In recent years, enormous progress has been achieved in the elucidation of structures and functions of light-harvesting (antenna) complexes, photosynthetic reaction centers and even entire photosystems. It is becoming increasingly clear that light-harvesting complexes not only serve to enlarge the absorption cross sections of the respective reaction centers but are vitally important in short- and long-term adaptation of the photosynthetic apparatus and regulation of the energy-transforming processes in response to external and internal conditions. Thus, the wide variety of structural diversity in photosynthetic antenna "designs" becomes conceivable. It is, however, common for LHCs to form trimeric (or multiples thereof) structures. We propose a simple, tentative explanation of the trimer issue, based on the 2D world created by photosynthetic membrane systems.
Topics: Bacterial Proteins; Cyanobacteria; Energy Transfer; Light-Harvesting Protein Complexes; Models, Molecular; Photosynthesis; Plant Proteins; Plants; Protein Conformation; Protein Multimerization
PubMed: 34204994
DOI: 10.3390/molecules26113378 -
Nature Apr 2023In oxygenic photosynthetic organisms, light energy is captured by antenna systems and transferred to photosystem II (PSII) and photosystem I (PSI) to drive...
In oxygenic photosynthetic organisms, light energy is captured by antenna systems and transferred to photosystem II (PSII) and photosystem I (PSI) to drive photosynthesis. The antenna systems of red algae consist of soluble phycobilisomes (PBSs) and transmembrane light-harvesting complexes (LHCs). Excitation energy transfer pathways from PBS to photosystems remain unclear owing to the lack of structural information. Here we present in situ structures of PBS-PSII-PSI-LHC megacomplexes from the red alga Porphyridium purpureum at near-atomic resolution using cryogenic electron tomography and in situ single-particle analysis, providing interaction details between PBS, PSII and PSI. The structures reveal several unidentified and incomplete proteins and their roles in the assembly of the megacomplex, as well as a huge and sophisticated pigment network. This work provides a solid structural basis for unravelling the mechanisms of PBS-PSII-PSI-LHC megacomplex assembly, efficient energy transfer from PBS to the two photosystems, and regulation of energy distribution between PSII and PSI.
Topics: Energy Transfer; Light-Harvesting Protein Complexes; Photosynthesis; Photosystem I Protein Complex; Photosystem II Protein Complex; Phycobilisomes; Porphyridium; Cryoelectron Microscopy; Single Molecule Imaging
PubMed: 36922595
DOI: 10.1038/s41586-023-05831-0 -
International Journal of Molecular... Jan 2023The emergence of chlorophyll-containing light-harvesting complexes (LHCs) was a crucial milestone in the evolution of photosynthetic eukaryotic organisms.... (Review)
Review
The emergence of chlorophyll-containing light-harvesting complexes (LHCs) was a crucial milestone in the evolution of photosynthetic eukaryotic organisms. Light-harvesting chlorophyll-binding proteins form complexes in proximity to the reaction centres of photosystems I and II and serve as an antenna, funnelling the harvested light energy towards the reaction centres, facilitating photochemical quenching, thereby optimizing photosynthesis. It is now generally accepted that the LHC proteins evolved from LHC-like proteins, a diverse family of proteins containing up to four transmembrane helices. Interestingly, LHC-like proteins do not participate in light harvesting to elevate photosynthesis activity under low light. Instead, they protect the photosystems by dissipating excess energy and taking part in non-photochemical quenching processes. Although there is evidence that LHC-like proteins are crucial factors of photoprotection, the roles of only a few of them, mainly the stress-related psbS and lhcSR, are well described. Here, we summarize the knowledge gained regarding the evolution and function of the various LHC-like proteins, with emphasis on those strongly related to photoprotection. We further suggest LHC-like proteins as candidates for improving photosynthesis in significant food crops and discuss future directions in their research.
Topics: Photosystem II Protein Complex; Photosynthesis; Chlorophyll; Light-Harvesting Protein Complexes; Eukaryota
PubMed: 36768826
DOI: 10.3390/ijms24032503 -
Microorganisms Apr 2022Photosystem II is a light-driven water-plastoquinone oxidoreductase present in cyanobacteria, algae and plants. It produces molecular oxygen and protons to drive ATP... (Review)
Review
Photosystem II is a light-driven water-plastoquinone oxidoreductase present in cyanobacteria, algae and plants. It produces molecular oxygen and protons to drive ATP synthesis, fueling life on Earth. As a multi-subunit membrane-protein-pigment complex, Photosystem II undergoes a dynamic cycle of synthesis, damage, and repair known as the Photosystem II lifecycle, to maintain a high level of photosynthetic activity at the cellular level. Cyanobacteria, oxygenic photosynthetic bacteria, are frequently used as model organisms to study oxygenic photosynthetic processes due to their ease of growth and genetic manipulation. The cyanobacterial PSII structure and function have been well-characterized, but its lifecycle is under active investigation. In this review, advances in studying the lifecycle of Photosystem II in cyanobacteria will be discussed, with a particular emphasis on new structural findings enabled by cryo-electron microscopy. These structural findings complement a rich and growing body of biochemical and molecular biology research into Photosystem II assembly and repair.
PubMed: 35630282
DOI: 10.3390/microorganisms10050836 -
Photosynthesis Research Oct 2019Biological water oxidation, performed by a single enzyme, photosystem II, is a central research topic not only in understanding the photosynthetic apparatus but also for... (Review)
Review
Biological water oxidation, performed by a single enzyme, photosystem II, is a central research topic not only in understanding the photosynthetic apparatus but also for the development of water splitting catalysts for technological applications. Great progress has been made in this endeavor following the report of a high-resolution X-ray crystallographic structure in 2011 resolving the cofactor site (Umena et al. in Nature 473:55-60, 2011), a tetra-manganese calcium complex. The electronic properties of the protein-bound water oxidizing MnOCa complex are crucial to understand its catalytic activity. These properties include: its redox state(s) which are tuned by the protein matrix, the distribution of the manganese valence and spin states and the complex interactions that exist between the four manganese ions. In this short review we describe how magnetic resonance techniques, particularly EPR, complemented by quantum chemical calculations, have played an important role in understanding the electronic structure of the cofactor. Together with isotope labeling, these techniques have also been instrumental in deciphering the binding of the two substrate water molecules to the cluster. These results are briefly described in the context of the history of biological water oxidation with special emphasis on recent work using time resolved X-ray diffraction with free electron lasers. It is shown that these data are instrumental for developing a model of the biological water oxidation cycle.
Topics: Bacterial Proteins; Crystallography, X-Ray; Cyanobacteria; Kinetics; Models, Biological; Models, Chemical; Models, Molecular; Oxidation-Reduction; Oxygen; Photosystem II Protein Complex; Protein Structure, Tertiary; Thermosynechococcus; Water
PubMed: 31187340
DOI: 10.1007/s11120-019-00648-3