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Environmental Research Jul 2024After the second industrial revolution, social productivity developed rapidly, and the use of fossil fuels such as coal, oil, and natural gas increased greatly in... (Review)
Review
After the second industrial revolution, social productivity developed rapidly, and the use of fossil fuels such as coal, oil, and natural gas increased greatly in industrial production. The burning of these fossil fuels releases large amounts of greenhouse gases such as CO, which has caused greenhouse effects and global warming. This has endangered the planet's ecological balance and brought many species, including animals and plants, to the brink of extinction. Thus, it is crucial to address this problem urgently. One potential solution is the use of syngas fermentation with microbial cell factories. This process can produce chemicals beneficial to humans, such as ethanol as a fuel while consuming large quantities of harmful gases, CO and CO. However, syngas-fermenting microorganisms often face a metabolic energy deficit, resulting in slow cell growth, metabolic disorders, and low product yields. This problem limits the large-scale industrial application of engineered microorganisms. Therefore, it is imperative to address the energy barriers of these microorganisms. This paper provides an overview of the current research progress in addressing energy barriers in bacteria, including the efficient capture of external energy and the regulation of internal energy metabolic flow. Capturing external energy involves summarizing studies on overexpressing natural photosystems and constructing semiartificial photosynthesis systems using photocatalysts. The regulation of internal energy metabolic flows involves two parts: regulating enzymes and metabolic pathways. Finally, the article discusses current challenges and future perspectives, with a focus on achieving both sustainability and profitability in an economical and energy-efficient manner. These advancements can provide a necessary force for the large-scale industrial application of syngas fermentation microbial cell factories.
Topics: Fermentation; Bacteria; Energy Metabolism; Biofuels
PubMed: 38574985
DOI: 10.1016/j.envres.2024.118813 -
The New Phytologist Sep 2023In natural ecosystems, plants compete for space, nutrients and light. The optically dense canopies limit the penetration of photosynthetically active radiation and light... (Review)
Review
In natural ecosystems, plants compete for space, nutrients and light. The optically dense canopies limit the penetration of photosynthetically active radiation and light often becomes a growth-limiting factor for the understory. The reduced availability of photons in the lower leaf layers is also a major constraint for yield potential in canopies of crop monocultures. Traditionally, crop breeding has selected traits related to plant architecture and nutrient assimilation rather than light use efficiency. Leaf optical density is primarily determined by tissue morphology and by the foliar concentration of photosynthetic pigments (chlorophylls and carotenoids). Most pigment molecules are bound to light-harvesting antenna proteins in the chloroplast thylakoid membranes, where they serve photon capture and excitation energy transfer toward reaction centers of photosystems. Engineering the abundance and composition of antenna proteins has been suggested as a strategy to improve light distribution within canopies and reduce the gap between theoretical and field productivity. Since the assembly of the photosynthetic antennas relies on several coordinated biological processes, many genetic targets are available for modulating cellular chlorophyll levels. In this review, we outline the rationale behind the advantages of developing pale green phenotypes and describe possible approaches toward engineering light-harvesting systems.
Topics: Chlorophyll; Light; Ecosystem; Plant Breeding; Photosynthesis; Plants; Plant Leaves
PubMed: 37282663
DOI: 10.1111/nph.19064 -
Biochemistry. Biokhimiia Oct 2023This work represents an overview of electron transport regulation in chloroplasts as considered in the context of structure-function organization of photosynthetic... (Review)
Review
This work represents an overview of electron transport regulation in chloroplasts as considered in the context of structure-function organization of photosynthetic apparatus in plants. Main focus of the article is on bifurcated oxidation of plastoquinol by the cytochrome bf complex, which represents the rate-limiting step of electron transfer between photosystems II and I. Electron transport along the chains of non-cyclic, cyclic, and pseudocyclic electron flow, their relationships to generation of the trans-thylakoid difference in electrochemical potentials of protons in chloroplasts, and pH-dependent mechanisms of regulation of the cytochrome bf complex are considered. Redox reactions with participation of molecular oxygen and ascorbate, alternative mediators of electron transport in chloroplasts, have also been discussed.
Topics: Electron Transport; Cytochrome b6f Complex; Cytochromes b; Electrons; Chloroplasts; Photosynthesis; Oxidation-Reduction
PubMed: 38105016
DOI: 10.1134/S0006297923100036 -
International Journal of Molecular... Nov 2023Grape rain-shelter cultivation is a widely employed practice in China. At present, the most commonly used rain shelter film materials are polyvinyl chloride (PVC),...
Grape rain-shelter cultivation is a widely employed practice in China. At present, the most commonly used rain shelter film materials are polyvinyl chloride (PVC), polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), and polyolefin (PO). Coverlys TF150 is a woven fabric with an internal antifoggy PE coating that has not yet been popularized as a rain shelter film for grapes in China. To investigate the effects of Coverlys TF150 on grapes, we measured the microdomain environment, leaf development, and photosynthetic characteristics of 'Miguang' ( × ) under rain-shelter cultivation and performed transcriptome analysis. The results showed that Coverlys TF150 significantly reduced ( < 0.05) the light intensity, temperature, and humidity compared with PO film, increased the chlorophyll content and leaf thickness (particularly palisade tissue thickness), and increased stomatal density and stomatal opening from 10:00 to 14:00. Coverlys TF150 was observed to improve the maximum efficiency of photosystem II (F/F), photochemical quenching (qP), the electron transfer rate (ETR), and the actual photochemical efficiency (Φ) from 10:00 to 14:00. Moreover, the net photosynthetic rate (P), intercellular CO concentration (C), stomatal conductance (G), and transpiration rate (T) of grape leaves significantly increased ( < 0.05) from 10:00 to 14:00. RNA-Seq analysis of the grape leaves at 8:00, 10:00, and 12:00 revealed 1388, 1562, and 1436 differential genes at these points in time, respectively. KEGG enrichment analysis showed the occurrence of protein processing in the endoplasmic reticulum. Plant hormone signal transduction and plant-pathogen interaction were identified as the metabolic pathways with the highest differential gene expression enrichment. The psbA encoding D1 protein was significantly up-regulated in both CO10vsPO10 and CO12vsPO12, while the sHSPs family genes were significantly down-regulated in all time periods, and thus may play an important role in the maintenance of the photosystem II (PSII) activity in grape leaves under Coverlys TF150. Compared with PO film, the PSI-related gene psaB was up-regulated, indicating the ability of Coverlys TF150 to better maintain PSI activity. Compared with PO film, the abolic acid receptacle-associated gene PYL1 was down-regulated at all time periods under the Coverlys TF150 treatment, while PP2C47 was significantly up-regulated in CO10vsPO10 and CO12vsPO12, inducing stomatal closure. The results reveal that Coverlys TF150 alleviates the stress of high temperature and strong light compared with PO film, improves the photosynthetic capacity of grape leaves, and reduces the midday depression of photosynthesis.
Topics: Vitis; Photosystem II Protein Complex; Photosynthesis; Chlorophyll; Light; Plant Leaves
PubMed: 38068982
DOI: 10.3390/ijms242316659 -
Plant Physiology Aug 2023In thylakoid membranes, photosystem II (PSII) monomers from the stromal lamellae contain the subunits PsbS and Psb27 (PSIIm-S/27), while PSII monomers (PSIIm) from...
In thylakoid membranes, photosystem II (PSII) monomers from the stromal lamellae contain the subunits PsbS and Psb27 (PSIIm-S/27), while PSII monomers (PSIIm) from granal regions lack these subunits. Here, we have isolated and characterized these 2 types of PSII complexes in tobacco (Nicotiana tabacum). PSIIm-S/27 showed enhanced fluorescence, the near absence of oxygen evolution, and limited and slow electron transfer from QA to QB compared to the near-normal activities in the granal PSIIm. However, when bicarbonate was added to PSIIm-S/27, water splitting and QA to QB electron transfer rates were comparable to those in granal PSIIm. The findings suggest that the binding of PsbS and/or Psb27 inhibits forward electron transfer and lowers the binding affinity for bicarbonate. This can be rationalized in terms of the recently discovered photoprotection role played by bicarbonate binding via the redox tuning of the QA/QA•- couple, which controls the charge recombination route, and this limits chlorophyll triplet-mediated 1O2 formation. These findings suggest that PSIIm-S/27 is an intermediate in the assembly of PSII in which PsbS and/or Psb27 restrict PSII activity while in transit using a bicarbonate-mediated switch and protective mechanism.
Topics: Photosystem II Protein Complex; Bicarbonates; Thylakoids; Electron Transport; Oxidation-Reduction
PubMed: 37202365
DOI: 10.1093/plphys/kiad275 -
The New Phytologist Dec 2023During photosynthesis, electron transport reactions generate and shuttle reductant to allow CO reduction by the Calvin-Benson-Bassham cycle and the formation of biomass... (Review)
Review
During photosynthesis, electron transport reactions generate and shuttle reductant to allow CO reduction by the Calvin-Benson-Bassham cycle and the formation of biomass building block in the so-called linear electron flow (LEF). However, in nature, environmental parameters like light intensity or CO availability can vary and quickly change photosynthesis rates, creating an imbalance between photosynthetic energy production and metabolic needs. In addition to LEF, alternative photosynthetic electron flows are central to allow photosynthetic energy to match metabolic demand in response to environmental variations. Microalgae arguably harbour one of the most diverse set of alternative electron flows (AEFs), including cyclic (CEF), pseudocyclic (PCEF) and chloroplast-to-mitochondria (CMEF) electron flow. While CEF, PCEF and CMEF have large functional overlaps, they differ in the conditions they are active and in their role for photosynthetic energy balance. Here, I review the molecular mechanisms of CEF, PCEF and CMEF in microalgae. I further propose a quantitative framework to compare their key physiological roles and quantify how the photosynthetic energy is partitioned to maintain a balanced energetic status of the cell. Key differences in AEF within the green lineage and the potential of rewiring photosynthetic electrons to enhance plant robustness will be discussed.
Topics: Electrons; Carbon Dioxide; Photosynthesis; Electron Transport; Light; Photosystem I Protein Complex
PubMed: 37872749
DOI: 10.1111/nph.19328 -
Nature Plants Aug 2023The heart of oxygenic photosynthesis is the water-splitting photosystem II (PSII), which forms supercomplexes with a variable amount of peripheral trimeric...
The heart of oxygenic photosynthesis is the water-splitting photosystem II (PSII), which forms supercomplexes with a variable amount of peripheral trimeric light-harvesting complexes (LHCII). Our knowledge of the structure of green plant PSII supercomplex is based on findings obtained from several representatives of green algae and flowering plants; however, data from a non-flowering plant are currently missing. Here we report a cryo-electron microscopy structure of PSII supercomplex from spruce, a representative of non-flowering land plants, at 2.8 Å resolution. Compared with flowering plants, PSII supercomplex in spruce contains an additional Ycf12 subunit, Lhcb4 protein is replaced by Lhcb8, and trimeric LHCII is present as a homotrimer of Lhcb1. Unexpectedly, we have found α-tocopherol (α-Toc)/α-tocopherolquinone (α-TQ) at the boundary between the LHCII trimer and the inner antenna CP43. The molecule of α-Toc/α-TQ is located close to chlorophyll a614 of one of the Lhcb1 proteins and its chromanol/quinone head is exposed to the thylakoid lumen. The position of α-Toc in PSII supercomplex makes it an ideal candidate for the sensor of excessive light, as α-Toc can be oxidized to α-TQ by high-light-induced singlet oxygen at low lumenal pH. The molecule of α-TQ appears to shift slightly into the PSII supercomplex, which could trigger important structure-functional modifications in PSII supercomplex. Inspection of the previously reported cryo-electron microscopy maps of PSII supercomplexes indicates that α-Toc/α-TQ can be present at the same site also in PSII supercomplexes from flowering plants, but its identification in the previous studies has been hindered by insufficient resolution.
Topics: Photosystem II Protein Complex; Cryoelectron Microscopy; alpha-Tocopherol; Thylakoids; Photosynthesis; Plants
PubMed: 37550369
DOI: 10.1038/s41477-023-01483-0 -
The Plant Cell Mar 2024The growth of plants, algae and cyanobacteria relies on the catalytic activity of the oxygen-evolving photosystem two (PSII) complex which uses solar energy to extract...
The growth of plants, algae and cyanobacteria relies on the catalytic activity of the oxygen-evolving photosystem two (PSII) complex which uses solar energy to extract electrons from water to feed into the photosynthetic electron transport chain. PSII is proving to be an excellent system to study how large multi-subunit membrane-protein complexes are assembled in the thylakoid membrane and subsequently repaired in response to photooxidative damage. Here we summarize recent developments in understanding the biogenesis of PSII, with an emphasis on recent insights obtained from biochemical and structural analysis of cyanobacterial PSII assembly/repair intermediates. We also discuss how chlorophyll synthesis is synchronized with protein synthesis and suggest a possible role for photosystem I in PSII assembly. Special attention is paid to unresolved and controversial issues that could be addressed in future research.
PubMed: 38484127
DOI: 10.1093/plcell/koae082 -
Journal of Molecular Biology Mar 2024Light is required for photosynthesis, but plants are often exposed to excess light, which can lead to photodamage and eventually cell death. To prevent this, they... (Review)
Review
Light is required for photosynthesis, but plants are often exposed to excess light, which can lead to photodamage and eventually cell death. To prevent this, they evolved photoprotective feedback mechanisms that regulate photosynthesis and trigger processes that dissipate light energy as heat, called non-photochemical quenching (NPQ). In excess light conditions, the light reaction and activity of Photosystem II (PSII) generates acidification of the thylakoid lumen, which is sensed by special pH-sensitive proteins called Photosystem II Subunit S (PsbS), actuating a photoprotective "switch" in the light-harvesting antenna. Despite its central role in regulating photosynthetic energy conversion, the molecular mechanism of PsbS as well as its interaction with partner proteins are not well understood. This review summarizes the current knowledge on the molecular structure and mechanistic aspects of the light-stress sensor PsbS and addresses open questions and challenges in the field regarding a full understanding of its functional mechanism and role in NPQ.
Topics: Light; Light-Harvesting Protein Complexes; Photosynthesis; Photosystem II Protein Complex; Plants; Protein Conformation
PubMed: 38109993
DOI: 10.1016/j.jmb.2023.168407 -
Ecotoxicology and Environmental Safety Sep 2023Polybrominated diphenyl ether (PBDE) contamination is common in aquatic environments and can severely damage aquatic organisms. However, there is a lack of information...
Polybrominated diphenyl ether (PBDE) contamination is common in aquatic environments and can severely damage aquatic organisms. However, there is a lack of information on the response and self-adaptation mechanisms of these organisms. Chlorella pyrenoidosa was treated with 2,2',4,4'-tetrabromodiphenyl ether (BDE47), causing significant growth inhibition, pigment reduction, oxidative stress, and chloroplast atrophy. Photosynthetic damage contributed to inhibition, as indicated by Fv/Fm, Chl a fluorescence induction, photosynthetic oxygen evolution activity, and photosystem subunit stoichiometry. Here, Chl a fluorescence induction and quinone electron acceptor (Q) reoxidation kinetics showed that the PSII donor and acceptor sides were insensitive to BDE47. Quantitative analyses of D1 and PsaD proteins illustrated that PSII and PSI complexes were the main primary targets of photosynthesis inhibition by BDE47. Significant modulation of PSII complex might have been caused by the potential binding of BDE47 on D1 protein, and molecular docking was performed to investigate this. Increased activation of antioxidant defense systems and photosystem repair as a function of exposure time indicated a positive resistance to BDE47. After a 5-day exposure, 23 % of BDE47 was metabolized. Our findings suggest that C. pyrenoidosa has potential as a bioremediator for wastewater-borne PBDEs and can improve our understanding of ecological risks to microalgae.
Topics: Halogenated Diphenyl Ethers; Chlorella; Molecular Docking Simulation; Photosynthesis; Electron Transport; Photosystem II Protein Complex
PubMed: 37451097
DOI: 10.1016/j.ecoenv.2023.115245