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Annual Review of Plant Biology Feb 2024Photosynthesis has been using energy from sunlight to assimilate atmospheric CO for at least 3.5 billion years. Through evolution and natural selection, photosynthetic... (Review)
Review
Photosynthesis has been using energy from sunlight to assimilate atmospheric CO for at least 3.5 billion years. Through evolution and natural selection, photosynthetic organisms have flourished in almost all aquatic and terrestrial environments. This is partly due to the diversity of light-harvesting complex (LHC) proteins, which facilitate photosystem assembly, efficient excitation energy transfer, and photoprotection. Structural advances have provided Ångström-level structures of many of these proteins and have expanded our understanding of the pigments, lipids, and residues that drive LHC function. In this review, we compare and contrast recently observed cryo-electron microscopy structures across photosynthetic eukaryotes to identify structural motifs that underlie various light-harvesting strategies. We discuss subtle monomer changes that result in macroscale reorganization of LHC oligomers. Additionally, we find recurring patterns across diverse LHCs that may serve as evolutionary stepping stones for functional diversification. Advancing our understanding of LHC protein-environment interactions will improve our capacity to engineer more productive crops. Expected final online publication date for the , Volume 75 is May 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
PubMed: 38360524
DOI: 10.1146/annurev-arplant-070623-015519 -
Plant Communications Nov 2023The sessile lifestyle of plants requires an immediate response to environmental stressors that affect photosynthesis, growth, and crop yield. Here, we showed that three...
The sessile lifestyle of plants requires an immediate response to environmental stressors that affect photosynthesis, growth, and crop yield. Here, we showed that three abiotic perturbations-heat, cold, and high light-triggered considerable changes in the expression signatures of 42 epitranscriptomic factors (writers, erasers, and readers) with putative chloroplast-associated functions that formed clusters of commonly expressed genes in Arabidopsis. The expression changes under all conditions were reversible upon deacclimation, identifying epitranscriptomic players as modulators in acclimation processes. Chloroplast dysfunctions, particularly those induced by the oxidative stress-inducing norflurazon in a largely GENOME UNCOUPLED-independent manner, triggered retrograde signals to remodel chloroplast-associated epitranscriptomic expression patterns. N-methyladenosine (mA) is known as the most prevalent RNA modification and impacts numerous developmental and physiological functions in living organisms. During cold treatment, expression of components of the primary nuclear mA methyltransferase complex was upregulated, accompanied by a significant increase in cellular mA mRNA marks. In the cold, the presence of FIP37, a core component of the writer complex, played an important role in positive regulation of thylakoid structure, photosynthetic functions, and accumulation of photosystem I, the Cytbf complex, cyclic electron transport proteins, and Curvature Thylakoid1 but not that of photosystem II components and the chloroplast ATP synthase. Downregulation of FIP37 affected abundance, polysomal loading, and translation of cytosolic transcripts related to photosynthesis in the cold, suggesting mA-dependent translational regulation of chloroplast functions. In summary, we identified multifaceted roles of the cellular mA RNA methylome in coping with cold; these were predominantly associated with chloroplasts and served to stabilize photosynthesis.
Topics: RNA; Epigenome; Light; Photosynthesis; Chloroplasts; Arabidopsis
PubMed: 37287225
DOI: 10.1016/j.xplc.2023.100634 -
Methods in Molecular Biology (Clifton,... 2024This chapter compares two different techniques for monitoring photosynthetic O production; the wide-spread Clark-type O electrode and the more sophisticated membrane...
This chapter compares two different techniques for monitoring photosynthetic O production; the wide-spread Clark-type O electrode and the more sophisticated membrane inlet mass spectrometry (MIMS) technique. We describe how a simple membrane inlet for MIMS can be made out of a commercial Clark-type cell and outline the advantages and drawbacks of the two techniques to guide researchers in deciding which method to use. Protocols and examples are given for measuring O evolution rates and for determining the number of chlorophyll molecules per active photosystem II reaction center.
Topics: Photosynthesis; Oxygen; Mass Spectrometry; Photosystem II Protein Complex; Chlorophyll; Electrodes
PubMed: 38649570
DOI: 10.1007/978-1-0716-3790-6_8 -
Plants (Basel, Switzerland) Mar 2024Oxygenic photosynthetic organisms use Photosystem II (PSII) to oxidize water and reduce plastoquinone. Here, we review the mechanisms by which PSII is assembled and... (Review)
Review
Oxygenic photosynthetic organisms use Photosystem II (PSII) to oxidize water and reduce plastoquinone. Here, we review the mechanisms by which PSII is assembled and turned over in the model green alga . This species has been used to make key discoveries in PSII research due to its metabolic flexibility and amenability to genetic approaches. PSII subunits originate from both nuclear and chloroplastic gene products in . Nuclear-encoded PSII subunits are transported into the chloroplast and chloroplast-encoded PSII subunits are translated by a coordinated mechanism. Active PSII dimers are built from discrete reaction center complexes in a process facilitated by assembly factors. The phosphorylation of core subunits affects supercomplex formation and localization within the thylakoid network. Proteolysis primarily targets the D1 subunit, which when replaced, allows PSII to be reactivated and completes a repair cycle. While PSII has been extensively studied using as a model species, important questions remain about its assembly and repair which are presented here.
PubMed: 38592843
DOI: 10.3390/plants13060811 -
Frontiers in Plant Science 2023The need to acclimate to different environmental conditions is central to the evolution of cyanobacteria. Far-red light (FRL) photoacclimation, or FaRLiP, is an...
The need to acclimate to different environmental conditions is central to the evolution of cyanobacteria. Far-red light (FRL) photoacclimation, or FaRLiP, is an acclimation mechanism that enables certain cyanobacteria to use FRL to drive photosynthesis. During this process, a well-defined gene cluster is upregulated, resulting in changes to the photosystems that allow them to absorb FRL to perform photochemistry. Because FaRLiP is widespread, and because it exemplifies cyanobacterial adaptation mechanisms in nature, it is of interest to understand its molecular evolution. Here, we performed a phylogenetic analysis of the photosystem I subunits encoded in the FaRLiP gene cluster and analyzed the available structural data to predict ancestral characteristics of FRL-absorbing photosystem I. The analysis suggests that FRL-specific photosystem I subunits arose relatively late during the evolution of cyanobacteria when compared with some of the FRL-specific subunits of photosystem II, and that the order Nodosilineales, which include strains like and sp. PCC 7335, could have obtained FaRLiP via horizontal gene transfer. We show that the ancestral form of FRL-absorbing photosystem I contained three chlorophyll -binding sites in the PsaB2 subunit, and a rotated chlorophyll molecule in the A site of the electron transfer chain. Along with our previous study of photosystem II expressed during FaRLiP, these studies describe the molecular evolution of the photosystem complexes encoded by the FaRLiP gene cluster.
PubMed: 38053766
DOI: 10.3389/fpls.2023.1289199 -
Biochemistry. Biokhimiia Oct 2023In the bioenergetics studies, the direct electrometric method played an important role. This method is based on measuring the electrical potential difference (Δψ)... (Review)
Review
In the bioenergetics studies, the direct electrometric method played an important role. This method is based on measuring the electrical potential difference (Δψ) between two compartments of the experimental cell generated by some membrane proteins. These proteins are incorporated into closed lipid-protein membrane vesicles associated with an artificial lipid membrane that separates the compartments. The very existence of such proteins able to generate Δψ was one of the consequences of Peter Mitchell's chemiosmotic concept. The discovery and investigation of their functioning contributed to the recognition of this concept and, eventually the well-deserved awarding of the Nobel Prize to P. Mitchell. Lel A. Drachev (1926-2022) was one of the main authors of the direct electrometrical method. With his participation, key studies were carried out on the electrogenesis of photosynthetic and respiratory membrane proteins, including bacteriorhodopsin, visual rhodopsin, photosynthetic bacterial reaction centers, cytochrome oxidase and others.
Topics: Photosynthetic Reaction Center Complex Proteins; Bacteria; Electron Transport Complex IV; Lipids
PubMed: 38105014
DOI: 10.1134/S0006297923100012 -
Nature Communications Apr 2024Dinoflagellates are ecologically important and essential to corals and other cnidarians as phytosymbionts, but their photosystems had been underexplored. Recently,...
Dinoflagellates are ecologically important and essential to corals and other cnidarians as phytosymbionts, but their photosystems had been underexplored. Recently, photosystem I (PSI) of dinoflagellate sp. was structurally characterized using cryo-Electron Microscopy (cryo-EM). These analyses revealed a distinct organization of the PSI supercomplex, including two previously unidentified subunits, PsaT and PsaU, and shed light on interactions between light harvesting antenna proteins and the PSI core. These results have implications with respect to the evolution of dinoflagellates and their association with cnidarians.
Topics: Photosystem I Protein Complex; Photosynthesis; Chlorophyll; Dinoflagellida; Photosystem II Protein Complex; Light; Light-Harvesting Protein Complexes
PubMed: 38637576
DOI: 10.1038/s41467-024-47797-1 -
The New Phytologist Oct 2023Drought is a major abiotic stress that impairs plant growth and development. Despite this, a comprehensive understanding of drought effects on the photosynthetic...
Drought is a major abiotic stress that impairs plant growth and development. Despite this, a comprehensive understanding of drought effects on the photosynthetic apparatus is lacking. In this work, we studied the consequences of 14-d drought treatment on Arabidopsis thaliana. We used biochemical and spectroscopic methods to examine photosynthetic membrane composition and functionality. Drought led to the disassembly of PSII supercomplexes and the degradation of PSII core. The light-harvesting complexes (LHCII) instead remain in the membrane but cannot act as an antenna for active PSII, thus representing a potential source of photodamage. This effect can also be observed during nonphotochemical quenching (NPQ) induction when even short pulses of saturating light can lead to photoinhibition. At a later stage, under severe drought stress, the PSI antenna size is also reduced and the PSI-LHCI supercomplexes disassemble. Surprisingly, although we did not observe changes in the PSI core protein content, the functionality of PSI is severely affected, suggesting the accumulation of nonfunctional PSI complexes. We conclude that drought affects both photosystems, although at a different stage, and that the operative quantum efficiency of PSII (Φ ) is very sensitive to drought and can thus be used as a parameter for early detection of drought stress.
Topics: Arabidopsis; Photosystem I Protein Complex; Droughts; Photosystem II Protein Complex; Photosynthesis; Light-Harvesting Protein Complexes; Chlorophyll
PubMed: 37530066
DOI: 10.1111/nph.19171 -
Journal of Biochemistry Oct 2023In biomembranes, lipids form bilayer structures that serve as the fluid matrix for membrane proteins and other hydrophobic compounds. Additionally, lipid molecules... (Review)
Review
In biomembranes, lipids form bilayer structures that serve as the fluid matrix for membrane proteins and other hydrophobic compounds. Additionally, lipid molecules associate with membrane proteins and impact their structures and functions. In both cyanobacteria and the chloroplasts of plants and algae, the lipid bilayer of the thylakoid membrane consists of four distinct glycerolipid classes: monogalactosyldiacylglycerol, digalactosyldiacylglycerol, sulfoquinovosyldiacylglycerol, and phosphatidylglycerol. These lipids are also integral components of photosynthetic complexes such as photosystem II and photosystem I. The lipid-binding sites within the photosystems, as well as the lipid composition in the thylakoid membrane, are highly conserved between cyanobacteria and photosynthetic eukaryotes, and each lipid class has specific roles in oxygenic photosynthesis. This review aims to shed light on the potential evolutionary implications of lipid utilization in membrane lipid bilayers and photosynthetic complexes in oxygenic photosynthetic organisms.
Topics: Chloroplasts; Thylakoids; Photosynthesis; Photosystem II Protein Complex; Cyanobacteria
PubMed: 37500078
DOI: 10.1093/jb/mvad058 -
Photosynthesis Research Nov 2023One of the reasons for the high efficiency and selectivity of biological catalysts arise from their ability to control the pathways of substrates and products using... (Review)
Review
One of the reasons for the high efficiency and selectivity of biological catalysts arise from their ability to control the pathways of substrates and products using protein channels, and by modulating the transport in the channels using the interaction with the protein residues and the water/hydrogen-bonding network. This process is clearly demonstrated in Photosystem II (PS II), where its light-driven water oxidation reaction catalyzed by the MnCaO cluster occurs deep inside the protein complex and thus requires the transport of two water molecules to and four protons from the metal center to the bulk water. Based on the recent advances in structural studies of PS II from X-ray crystallography and cryo-electron microscopy, in this review we compare the channels that have been proposed to facilitate this mass transport in cyanobacteria, red and green algae, diatoms, and higher plants. The three major channels (O1, O4, and Cl1 channels) are present in all species investigated; however, some differences exist in the reported structures that arise from the different composition and arrangement of membrane extrinsic subunits between the species. Among the three channels, the Cl1 channel, including the proton gate, is the most conserved among all photosynthetic species. We also found at least one branch for the O1 channel in all organisms, extending all the way from Ca/O1 via the 'water wheel' to the lumen. However, the extending path after the water wheel varies between most species. The O4 channel is, like the Cl1 channel, highly conserved among all species while having different orientations at the end of the path near the bulk. The comparison suggests that the previously proposed functionality of the channels in T. vestitus (Ibrahim et al., Proc Natl Acad Sci USA 117:12624-12635, 2020; Hussein et al., Nat Commun 12:6531, 2021) is conserved through the species, i.e. the O1-like channel is used for substrate water intake, and the tighter Cl1 and O4 channels for proton release. The comparison does not eliminate the potential role of O4 channel as a water intake channel. However, the highly ordered hydrogen-bonded water wire connected to the MnCaO cluster via the O4 may strongly suggest that it functions in proton release, especially during the S → S transition (Saito et al., Nat Commun 6:8488, 2015; Kern et al., Nature 563:421-425, 2018; Ibrahim et al., Proc Natl Acad Sci USA 117:12624-12635, 2020; Sakashita et al., Phys Chem Chem Phys 22:15831-15841, 2020; Hussein et al., Nat Commun 12:6531, 2021).
Topics: Protons; Photosystem II Protein Complex; Water; Cryoelectron Microscopy; Oxidation-Reduction
PubMed: 37266800
DOI: 10.1007/s11120-023-01018-w