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International Journal of Molecular... Jan 2022MicroRNA408 () is an ancient and highly conserved miRNA, which is involved in the regulation of plant growth, development and stress response. However, previous research... (Review)
Review
MicroRNA408 () is an ancient and highly conserved miRNA, which is involved in the regulation of plant growth, development and stress response. However, previous research results on the evolution and functional roles of and its targets are relatively scattered, and there is a lack of a systematic comparison and comprehensive summary of the detailed evolutionary pathways and regulatory mechanisms of and its targets in plants. Here, we analyzed the evolutionary pathway of in plants, and summarized the functions of and its targets in regulating plant growth and development and plant responses to various abiotic and biotic stresses. The evolutionary analysis shows that is an ancient and highly conserved microRNA, which is widely distributed in different plants. regulates the growth and development of different plants by down-regulating its targets, encoding blue copper (Cu) proteins, and by transporting Cu to plastocyanin (PC), which affects photosynthesis and ultimately promotes grain yield. In addition, improves tolerance to stress by down-regulating target genes and enhancing cellular antioxidants, thereby increasing the antioxidant capacity of plants. This review expands and promotes an in-depth understanding of the evolutionary and regulatory roles of and its targets in plants.
Topics: Biological Evolution; Gene Expression Regulation, Plant; MicroRNAs; Multigene Family; Organ Specificity; Plant Development; Plant Physiological Phenomena; RNA, Messenger; RNA, Plant; Stress, Physiological
PubMed: 35008962
DOI: 10.3390/ijms23010530 -
Biochimica Et Biophysica Acta Mar 2011The photosynthetic electron transport chain consists of photosystem II, the cytochrome b(6)f complex, photosystem I, and the free electron carriers plastoquinone and... (Review)
Review
The photosynthetic electron transport chain consists of photosystem II, the cytochrome b(6)f complex, photosystem I, and the free electron carriers plastoquinone and plastocyanin. Light-driven charge separation events occur at the level of photosystem II and photosystem I, which are associated at one end of the chain with the oxidation of water followed by electron flow along the electron transport chain and concomitant pumping of protons into the thylakoid lumen, which is used by the ATP synthase to generate ATP. At the other end of the chain reducing power is generated, which together with ATP is used for CO(2) assimilation. A remarkable feature of the photosynthetic apparatus is its ability to adapt to changes in environmental conditions by sensing light quality and quantity, CO(2) levels, temperature, and nutrient availability. These acclimation responses involve a complex signaling network in the chloroplasts comprising the thylakoid protein kinases Stt7/STN7 and Stl1/STN7 and the phosphatase PPH1/TAP38, which play important roles in state transitions and in the regulation of electron flow as well as in thylakoid membrane folding. The activity of some of these enzymes is closely connected to the redox state of the plastoquinone pool, and they appear to be involved both in short-term and long-term acclimation. This article is part of a Special Issue entitled "Regulation of Electron Transport in Chloroplasts".
Topics: Electron Transport; Oxidation-Reduction; Photosynthesis; Signal Transduction
PubMed: 21118674
DOI: 10.1016/j.bbabio.2010.11.010 -
Biochimica Et Biophysica Acta Sep 2015Photosystem I, an integral membrane and multi-subunit complex, catalyzes the oxidation of plastocyanin and the reduction of ferredoxin by absorbed light energy.... (Review)
Review
Photosystem I, an integral membrane and multi-subunit complex, catalyzes the oxidation of plastocyanin and the reduction of ferredoxin by absorbed light energy. Photosystem I participates in photosynthetic acclimation processes by being involved in cyclic electron transfer and state transitions for sustaining efficient photosynthesis. The photosystem I complex is highly conserved from cyanobacteria to higher plants and contains the light-harvesting complex and the reaction center complex. The assembly of the photosystem I complex is highly complicated and involves the concerted assembly of multiple subunits and hundreds of cofactors. A suite of regulatory factors for the assembly of photosystem I subunits and cofactors have been identified that constitute an integrative network regulating PSI accumulation. This review aims to discuss recent findings in the field relating to how the photosystem I complex is assembled in oxygenic organisms. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
Topics: Evolution, Molecular; Photosystem I Protein Complex; Protein Subunits
PubMed: 25582571
DOI: 10.1016/j.bbabio.2014.12.011 -
Biochimica Et Biophysica Acta.... Nov 2020Plastocyanin and cytochrome c, abundant proteins in photosynthesis, are readouts for cellular copper status in Chlamydomonas and other algae. Their accumulation is... (Review)
Review
Plastocyanin and cytochrome c, abundant proteins in photosynthesis, are readouts for cellular copper status in Chlamydomonas and other algae. Their accumulation is controlled by a transcription factor copper response regulator (CRR1). The replacement of copper-containing plastocyanin with heme-containing cytochrome c spares copper and permits preferential copper (re)-allocation to cytochrome oxidase. Under copper-replete situations, the quota depends on abundance of various cuproproteins and is tightly regulated, except under zinc-deficiency where acidocalcisomes over-accumulate Cu(I). CRR1 has a transcriptional activation domain, a Zn-dependent DNA binding SBP-domain with a nuclear localization signal, and a C-terminal Cys-rich region that represses the zinc regulon. CRR1 activates >60 genes in Chlamydomonas through GTAC-containing CuREs; transcriptome differences are recapitulated in the proteome. The differentially-expressed genes encode assimilatory copper transporters of the CTR/SLC31 family including a novel soluble molecule, redox enzymes in the tetrapyrrole pathway that promote chlorophyll biosynthesis and photosystem 1 accumulation, and other oxygen-dependent enzymes, which may influence thylakoid membrane lipids, specifically polyunsaturated galactolipids and γ-tocopherol. CRR1 also down-regulates 2 proteins in Chlamydomonas: for plastocyanin, by activation of proteolysis, while for the di‑iron subunit of the cyclase in chlorophyll biosynthesis, through activation of an upstream promoter that generates a poorly-translated 5' extended transcript containing multiple short ORFs that inhibit translation. The functions of many CRR1-target genes are unknown, and the copper protein inventory in Chlamydomonas includes several whose functions are unexplored. The comprehensive picture of cuproproteins and copper homeostasis in this system is well-suited for reverse genetic analyses of these under-investigated components in copper biology.
Topics: Chlamydomonas; Copper; Cytochromes c6; Dihydrodipicolinate Reductase; Electron Transport Complex IV; Gene Expression Regulation, Plant; Homeostasis; Photosynthesis; Plastocyanin; Transcriptome
PubMed: 32800924
DOI: 10.1016/j.bbamcr.2020.118822 -
The Biochemical Journal Apr 2018The photosynthetic chloroplast thylakoid membrane of higher plants is a complex three-dimensional structure that is morphologically dynamic on a timescale of just a few... (Review)
Review
The photosynthetic chloroplast thylakoid membrane of higher plants is a complex three-dimensional structure that is morphologically dynamic on a timescale of just a few minutes. The membrane dynamics are driven by the phosphorylation of light-harvesting complex II (LHCII) by the STN7 kinase, which controls the size of the stacked grana region relative to the unstacked stromal lamellae region. Here, I hypothesise that the functional significance of these membrane dynamics is in controlling the partition of electrons between photosynthetic linear and cyclic electron transfer (LET and CET), which determines the ratio of NADPH/ATP produced. The STN7 kinase responds to the metabolic state of the chloroplast by sensing the stromal redox state. A high NADPH/ATP ratio leads to reduction of thioredoxin f (TRX), which reduces a CxxxC motif in the stromal domain of STN7 leading to its inactivation, whereas a low NADPH/ATP ratio leads to oxidation of TRX and STN7 activation. Phosphorylation of LHCII leads to smaller grana, which favour LET by speeding up diffusion of electron carriers plastoquinone (PQ) and plastocyanin (PC) between the domains. In contrast, dephosphorylation of LHCII leads to larger grana that slow the diffusion of PQ and PC, leaving the PQ pool in the stroma more oxidised, thus enhancing the efficiency of CET. The feedback regulation of electron transfer by the downstream metabolism is crucial to plant fitness, since perturbations in the NADPH/ATP ratio can rapidly lead to the inhibition of photosynthesis and photo-oxidative stress.
Topics: Arabidopsis; Arabidopsis Proteins; Electron Transport; Photosynthesis; Photosystem II Protein Complex; Thylakoids
PubMed: 29622671
DOI: 10.1042/BCJ20170526 -
Nature Plants Oct 2022Photosystem I (PSI) enables photo-electron transfer and regulates photosynthesis in the bioenergetic membranes of cyanobacteria and chloroplasts. Being a multi-subunit...
Photosystem I (PSI) enables photo-electron transfer and regulates photosynthesis in the bioenergetic membranes of cyanobacteria and chloroplasts. Being a multi-subunit complex, its macromolecular organization affects the dynamics of photosynthetic membranes. Here we reveal a chloroplast PSI from the green alga Chlamydomonas reinhardtii that is organized as a homodimer, comprising 40 protein subunits with 118 transmembrane helices that provide scaffold for 568 pigments. Cryogenic electron microscopy identified that the absence of PsaH and Lhca2 gives rise to a head-to-head relative orientation of the PSI-light-harvesting complex I monomers in a way that is essentially different from the oligomer formation in cyanobacteria. The light-harvesting protein Lhca9 is the key element for mediating this dimerization. The interface between the monomers is lacking PsaH and thus partially overlaps with the surface area that would bind one of the light-harvesting complex II complexes in state transitions. We also define the most accurate available PSI-light-harvesting complex I model at 2.3 Å resolution, including a flexibly bound electron donor plastocyanin, and assign correct identities and orientations to all the pigments, as well as 621 water molecules that affect energy transfer pathways.
Topics: Photosystem I Protein Complex; Plastocyanin; Light-Harvesting Protein Complexes; Protein Subunits; Cyanobacteria; Water; Photosystem II Protein Complex
PubMed: 36229605
DOI: 10.1038/s41477-022-01253-4 -
The FEBS Journal May 2011Electron transfer proteins transport electrons safely between large redox enzymes. The complexes formed by these proteins are among the most transient. The biological... (Review)
Review
Electron transfer proteins transport electrons safely between large redox enzymes. The complexes formed by these proteins are among the most transient. The biological function requires, on the one hand, sufficient specificity of the interaction to allow for rapid and selective electron transfer, and, on the other hand, a fast turnover of the complex. Recent progress in the characterization of the nature of these complexes has demonstrated that the encounter state plays an important role. This state of initial binding is dominated by electrostatic interactions, and consists of an ensemble of orientations. Paramagnetic relaxation enhancement NMR and chemical shift perturbation analysis provide ways for the experimental characterisation of the encounter state. Several studies that have used these techniques have shown that the surface area sample in the encounter state can be limited to the immediate environment of the final, specific complex. The encounter complex can represent a large fraction and, in some small complexes, no specific binding is detected at all. It can be concluded that, in electron transfer protein complexes, a fine balance is sought between the low-specificity encounter state and the high-specificity productive complex to meet the opposing requirements of rapid electron transfer and a high turnover rate.
Topics: Cytochromes c; Electron Transport; Electron Transport Complex IV; Models, Molecular; Nuclear Magnetic Resonance, Biomolecular; Plastocyanin; Proteins
PubMed: 21352493
DOI: 10.1111/j.1742-4658.2011.08062.x -
Biochimica Et Biophysica Acta Jan 2000The review covers the theory and practice of the determination of kinetic constants for the electron transfer reactions in chloroplast thylakoid membranes between... (Review)
Review
The review covers the theory and practice of the determination of kinetic constants for the electron transfer reactions in chloroplast thylakoid membranes between plastocyanin and cytochrome f in cytochrome bf complexes, and between plastocyanin and the reaction centre of photosystem I. Effects of ionic strength and pH are featured. The contribution of mutant studies is included. It is concluded that nearly all data from in vitro experiments can be interpreted with a reaction scheme in which an encounter complex between donor and acceptor is formed by long-range electrostatic attraction, followed by rearrangement during which metal centres become close enough for rapid intra-complex electron transfer. In vivo experiments so far cast doubt on this particular sequence, but their interpretation is not straightforward. Means of modelling the bimolecular complex between cytochrome f and plastocyanin are outlined, and two likely structures are illustrated. The complex formed by plastocyanin and photosystem I in higher plants involves the PsaF subunit, but its structure has not been fully determined.
Topics: Chlorophyll; Cytochromes; Cytochromes f; Electron Transport; Hydrogen-Ion Concentration; Kinetics; Light-Harvesting Protein Complexes; Membrane Proteins; Models, Chemical; Models, Molecular; Osmolar Concentration; Photosynthetic Reaction Center Complex Proteins; Photosystem I Protein Complex; Plastocyanin; Static Electricity; Thylakoids
PubMed: 10611452
DOI: 10.1016/s0005-2728(99)00101-2 -
Biochimica Et Biophysica Acta.... Sep 2021Many cyanobacteria species can use both plastocyanin and cytochrome c as lumenal electron carriers to shuttle electrons from the cytochrome bf to either photosystem I or...
Many cyanobacteria species can use both plastocyanin and cytochrome c as lumenal electron carriers to shuttle electrons from the cytochrome bf to either photosystem I or the respiratory cytochrome c oxidase. In Synechocystis sp. PCC6803 placed in darkness, about 60% of the active PSI centres are bound to a reduced electron donor which is responsible for the fast re-reduction of Pin vivo after a single charge separation. Here, we show that both cytochrome c and plastocyanin can bind to PSI in the dark and participate to the fast phase of P reduction, but the fraction of pre-bound PSI is smaller in the case of cytochrome c than with plastocyanin. Because of the inter-connection of respiration and photosynthesis in cyanobacteria, the inhibition of the cytochrome c oxidase results in the over-reduction of the photosynthetic electron transfer chain in the dark that translates into a lag in the kinetics of P oxidation at the onset of light. We show that this is true both with plastocyanin and cytochrome c, indicating that the partitioning of electron transport between respiration and photosynthesis is regulated in the same way independently of which of the two lumenal electron carriers is present, although the mechanisms of such regulation are yet to be understood.
Topics: Chlorophyll; Cyanobacteria; Cytochromes c6; Electron Transport; Electron Transport Complex IV; Kinetics; Oxidation-Reduction; Photosynthesis; Photosystem I Protein Complex; Plastocyanin; Synechocystis; Thylakoids
PubMed: 34004195
DOI: 10.1016/j.bbabio.2021.148449 -
Frontiers in Plant Science Oct 2013It has been known for a long time that the thylakoid lumen provides the environment for oxygen evolution, plastocyanin-mediated electron transfer, and photoprotection.... (Review)
Review
It has been known for a long time that the thylakoid lumen provides the environment for oxygen evolution, plastocyanin-mediated electron transfer, and photoprotection. More recently lumenal proteins have been revealed to play roles in numerous processes, most often linked with regulating thylakoid biogenesis and the activity and turnover of photosynthetic protein complexes, especially the photosystem II and NAD(P)H dehydrogenase-like complexes. Still, the functions of the majority of lumenal proteins in Arabidopsis thaliana are unknown. Interestingly, while the thylakoid lumen proteome of at least 80 proteins contains several large protein families, individual members of many protein families have highly divergent roles. This is indicative of evolutionary pressure leading to neofunctionalization of lumenal proteins, emphasizing the important role of the thylakoid lumen for photosynthetic electron transfer and ultimately for plant fitness. Furthermore, the involvement of anterograde and retrograde signaling networks that regulate the expression and activity of lumen proteins is increasingly pertinent. Recent studies have also highlighted the importance of thiol/disulfide modulation in controlling the functions of many lumenal proteins and photosynthetic regulation pathways.
PubMed: 24198822
DOI: 10.3389/fpls.2013.00434