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1.
Molecules ; 25(18)2020 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-32899754

RESUMO

The emergence of the Coronavirus Disease 2019 (COVID-19) caused by the SARS-CoV-2 virus has led to an unprecedented pandemic, which demands urgent development of antiviral drugs and antibodies; as well as prophylactic approaches, namely vaccines. Algae biotechnology has much to offer in this scenario given the diversity of such organisms, which are a valuable source of antiviral and anti-inflammatory compounds that can also be used to produce vaccines and antibodies. Antivirals with possible activity against SARS-CoV-2 are summarized, based on previously reported activity against Coronaviruses or other enveloped or respiratory viruses. Moreover, the potential of algae-derived anti-inflammatory compounds to treat severe cases of COVID-19 is contemplated. The scenario of producing biopharmaceuticals in recombinant algae is presented and the cases of algae-made vaccines targeting viral diseases is highlighted as valuable references for the development of anti-SARS-CoV-2 vaccines. Successful cases in the production of functional antibodies are described. Perspectives on how specific algae species and genetic engineering techniques can be applied for the production of anti-viral compounds antibodies and vaccines against SARS-CoV-2 are provided.


Assuntos
Antivirais/farmacologia , Produtos Biológicos/farmacologia , Chlamydomonas reinhardtii/genética , Infecções por Coronavirus/tratamento farmacológico , Lectinas/farmacologia , Pneumonia Viral/tratamento farmacológico , Polifenóis/farmacologia , Polissacarídeos/farmacologia , Antivirais/química , Antivirais/isolamento & purificação , Betacoronavirus/efeitos dos fármacos , Betacoronavirus/patogenicidade , Produtos Biológicos/química , Produtos Biológicos/isolamento & purificação , Núcleo Celular/química , Núcleo Celular/genética , Núcleo Celular/metabolismo , Chlamydomonas reinhardtii/química , Chlamydomonas reinhardtii/metabolismo , Cloroplastos/química , Cloroplastos/genética , Cloroplastos/metabolismo , Infecções por Coronavirus/prevenção & controle , Engenharia Genética/métodos , Humanos , Lectinas/química , Lectinas/isolamento & purificação , Coronavírus da Síndrome Respiratória do Oriente Médio/efeitos dos fármacos , Coronavírus da Síndrome Respiratória do Oriente Médio/patogenicidade , Pandemias , Polifenóis/química , Polifenóis/isolamento & purificação , Polissacarídeos/química , Polissacarídeos/isolamento & purificação , Vírus da SARS/efeitos dos fármacos , Vírus da SARS/patogenicidade , Síndrome Respiratória Aguda Grave/tratamento farmacológico , Vacinas Virais/biossíntese , Vacinas Virais/farmacologia
2.
Ecotoxicol Environ Saf ; 202: 110955, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800229

RESUMO

The effects of cadmium (Cd) have been investigated in an aquatic plant Ottelia alismoides grown under low CO2. Under low CO2, no Cd treated O. alismoides operated three carbon dioxide-concentrating mechanisms (CCMs) efficiently, including HCO3- acquisition, C4 and CAM photosynthesis. After 4 days of treatment with 200 µM and 2000 µM Cd, O. alismoides exhibited an elevated Cd accumulation along with the increasing Cd concentration. Both Cd treatments induced appreciable phytotoxicities in O. alismoides. The leaves showed chlorosis symptoms and the anatomy as well as chloroplast ultrastructure were obviously damaged. Significant decreases in the content of pigments, chlorophyll fluorescence (Fv/Fm and Yield of PS II) and carbon isotope ratio (δ13C) were measured in leaf extracts of O. alismoides grown with both concentrations of Cd. In addition, the pH-drift technique showed that both Cd-treated O. alismoides plants could not uptake HCO3-. The maximum and minimum acidity in Cd-exposed O. alismoides were greatly decreased and the diurnal change of acidity was absent in both Cd treated plants. Furthermore, significant decreases in ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), pyruvate phosphate dikinase (PPDK) and phosphoenolpyruvate carboxylase (PEPC) activities were also found at Cd treated O. alismoides plants, indicating the disturbance within C4 cycle. The alterations in the functionality of CCMs in O. alismoides induced by Cd might be related with the inhibition of the enzymes such as carbonic anhydrase (CA) and PEPC involved in inorganic carbon fixation, and the destruction of chloroplasts, as well as the re-allocation of energy and nutrients involved in CCMs and Cd detoxification.


Assuntos
Organismos Aquáticos/efeitos dos fármacos , Cádmio/toxicidade , Dióxido de Carbono/metabolismo , Hydrocharitaceae/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Organismos Aquáticos/metabolismo , Anidrases Carbônicas/metabolismo , Cloroplastos/metabolismo , Hydrocharitaceae/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo
3.
PLoS One ; 15(8): e0237569, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817667

RESUMO

Several 'super-complexes' of individual hetero-oligomeric membrane protein complexes, whose function is to facilitate intra-membrane electron and proton transfer and harvesting of light energy, have been previously characterized in the mitochondrial cristae and chloroplast thylakoid membranes. We report the presence of an intra-membrane super-complex dominated by the ATP-synthase, photosystem I (PSI) reaction-center complex and the ferredoxin-NADP+ Reductase (FNR) in the thylakoid membrane. The presence of the super-complex has been documented by mass spectrometry, clear-native PAGE and Western Blot analyses. This is the first documented presence of ATP synthase in a super-complex with the PSI reaction-center located in the non-appressed stromal domain of the thylakoid membrane.


Assuntos
Cloroplastos/metabolismo , Ferredoxina-NADP Redutase/metabolismo , Óxido Nítrico Sintase/metabolismo , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , ATPases Translocadoras de Prótons/metabolismo , Tilacoides/metabolismo , Trifosfato de Adenosina/metabolismo , Transporte de Elétrons , Fotossíntese , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Spinacia oleracea/crescimento & desenvolvimento , Spinacia oleracea/metabolismo
4.
Postepy Biochem ; 66(2): 134-142, 2020 06 27.
Artigo em Polonês | MEDLINE | ID: mdl-32700507

RESUMO

The light phase of photosynthesis is a key energy process in higher plants. Its purpose is to convert light energy into chemical one stored in ATP and NADPH molecules, which are then used to assimilate CO2 and in numerous metabolic processes. Maintaining optimal photosynthesis performance requires strict regulation of thylakoid membranes organization and rapid response to changing environmental conditions. The main factor affecting photosynthesis is light, which, if applied in excessive amounts, leads to a slowdown in the process. Therefore, plants have developed many protective mechanisms regulating the light reactions of photosynthesis and operating at the level of light energy absorption, electron transport, and the distribution and use of reducing power. These include, among others: (i) non-photochemical energy quenching regulating the amount of excitation energy delivered to the photosystems; (ii) 'state transition' process redistributing excitation energy between photosystems; (iii) redundant electron transport pathways responsible for maintaining redox balance in chloroplasts. All these mechanisms, in combination with antioxidant systems, are designed to maintain the function of the photosynthetic apparatus in adverse growth conditions.


Assuntos
Fotossíntese/efeitos da radiação , Plantas/metabolismo , Plantas/efeitos da radiação , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Transporte de Elétrons/efeitos da radiação , Oxirredução/efeitos da radiação
5.
Nat Commun ; 11(1): 2882, 2020 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-32513940

RESUMO

Complex polyketides are typically associated with microbial metabolism. Here, we report that animals also make complex, microbe-like polyketides. We show there is a widespread branch of fatty acid synthase- (FAS)-like polyketide synthase (PKS) proteins, which sacoglossan animals use to synthesize complex products. The purified sacogolassan protein EcPKS1 uses only methylmalonyl-CoA as a substrate, otherwise unknown in animal lipid metabolism. Sacoglossans are sea slugs, some of which eat algae, digesting the cells but maintaining functional chloroplasts. Here, we provide evidence that polyketides support this unusual photosynthetic partnership. The FAS-like PKS family represents an uncharacterized branch of polyketide and fatty acid metabolism, encoding a large diversity of biomedically relevant animal enzymes and chemicals awaiting discovery. The biochemical characterization of an intact animal polyketide biosynthetic enzyme opens the door to understanding the immense untapped metabolic potential of metazoans.


Assuntos
Fotossíntese , Policetídeos/metabolismo , Acil Coenzima A/metabolismo , Animais , Cloroplastos/metabolismo , Escherichia coli/metabolismo , Ácido Graxo Sintases/química , Ácido Graxo Sintases/metabolismo , Gastrópodes/classificação , NADP/metabolismo , Filogenia , Policetídeo Sintases/química , Policetídeo Sintases/metabolismo , Policetídeos/química , Propionatos/química , Propionatos/metabolismo
6.
Plant Mol Biol ; 104(1-2): 39-53, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32564178

RESUMO

Plants are exposed to various environmental cues that lead to reactive oxygen species (ROS) accumulation. ROS production and detoxification are tightly regulated to maintain balance. Although studies of glucose (Glc) are always accompanied by ROS in animals, the role of Glc in respect of ROS in plants is unclear. We isolated gsm2 (Glc-hypersensitive mutant 2), a mutant with a notably chlorotic-cotyledon phenotype. The chloroplast-localized GSM2 was characterized as a transaldolase in the pentose phosphate pathway. With 3% Glc treatment, fewer or no thylakoids were observed in gsm2 cotyledon chloroplasts than in wild-type cotyledon chloroplasts, suggesting that GSM2 is required for chloroplast protection under stress. gsm2 also showed evaluated accumulation of ROS with 3% Glc treatment and was more sensitive to exogenous H2O2 than the wild type. Gene expression analysis of the antioxidant enzymes in gsm2 revealed that chloroplast damage to gsm2 cotyledons results from the accumulation of excessive ROS in response to Glc. Moreover, the addition of diphenyleneiodonium chloride or phenylalanine can rescue Glc-induced chlorosis in gsm2 cotyledons. This work suggests that GSM2 functions to maintain ROS balance in response to Glc during early seedling growth and sheds light on the relationship between Glc, the pentose phosphate pathway and ROS.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Homeostase , RNA Helicases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transaldolase/metabolismo , Ácido Abscísico/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Clorofila/metabolismo , Cloroplastos/genética , Cloroplastos/metabolismo , Cotilédone/metabolismo , Regulação da Expressão Gênica de Plantas , Germinação , Glucuronidase/metabolismo , Peróxido de Hidrogênio/metabolismo , Via de Pentose Fosfato/genética , Via de Pentose Fosfato/fisiologia , Fenótipo , RNA Helicases/genética , RNA de Plantas/genética , RNA de Plantas/isolamento & purificação , Plântula/genética , Plântula/metabolismo , Transaldolase/genética
7.
Nat Commun ; 11(1): 3238, 2020 06 26.
Artigo em Inglês | MEDLINE | ID: mdl-32591540

RESUMO

The challenge of monitoring in planta dynamic changes of NADP(H) and NAD(H) redox states at the subcellular level is considered a major obstacle in plant bioenergetics studies. Here, we introduced two circularly permuted yellow fluorescent protein sensors, iNAP and SoNar, into Arabidopsis thaliana to monitor the dynamic changes in NADPH and the NADH/NAD+ ratio. In the light, photosynthesis and photorespiration are linked to the redox states of NAD(P)H and NAD(P) pools in several subcellular compartments connected by the malate-OAA shuttles. We show that the photosynthetic increases in stromal NADPH and NADH/NAD+ ratio, but not ATP, disappear when glycine decarboxylation is inhibited. These observations highlight the complex interplay between chloroplasts and mitochondria during photosynthesis and support the suggestions that, under normal conditions, photorespiration supplies a large amount of NADH to mitochondria, exceeding its NADH-dissipating capacity, and the surplus NADH is exported from the mitochondria to the cytosol through the malate-OAA shuttle.


Assuntos
Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Luz , Proteínas Luminescentes/metabolismo , NADP/metabolismo , NAD/metabolismo , Fotossíntese/efeitos da radiação , Respiração Celular/efeitos da radiação , Cloroplastos/metabolismo , Citosol/metabolismo , Transporte de Elétrons/efeitos da radiação , Malatos/metabolismo , Mitocôndrias/metabolismo , Modelos Biológicos , Oxirredução , Peroxissomos/metabolismo , Plântula/metabolismo , Plântula/efeitos da radiação
8.
Science ; 368(6491): 649-654, 2020 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-32381722

RESUMO

Nature integrates complex biosynthetic and energy-converting tasks within compartments such as chloroplasts and mitochondria. Chloroplasts convert light into chemical energy, driving carbon dioxide fixation. We used microfluidics to develop a chloroplast mimic by encapsulating and operating photosynthetic membranes in cell-sized droplets. These droplets can be energized by light to power enzymes or enzyme cascades and analyzed for their catalytic properties in multiplex and real time. We demonstrate how these microdroplets can be programmed and controlled by adjusting internal compositions and by using light as an external trigger. We showcase the capability of our platform by integrating the crotonyl-coenzyme A (CoA)/ethylmalonyl-CoA/hydroxybutyryl-CoA (CETCH) cycle, a synthetic network for carbon dioxide conversion, to create an artificial photosynthetic system that interfaces the natural and the synthetic biological worlds.


Assuntos
Dióxido de Carbono/metabolismo , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Acil Coenzima A , Biocatálise , Biomimética , Ciclo do Carbono , Luz , Fotossíntese/efeitos da radiação , Spinacia oleracea
9.
PLoS One ; 15(5): e0233302, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32437457

RESUMO

When exposed to fluctuating light intensity, chloroplasts move towards weak light (accumulation response), and away from strong light (avoidance response). In addition, cold treatment (5°C) induces the avoidance response even under weak-light conditions (cold-avoidance response). These three responses are mediated by the phototropin (phot), which is a blue-light photoreceptor and has also been reported to act as a thermosensory protein that perceives temperature variation. Our previous report indicated that cold-induced changes in phot biochemical activity initiate the cold-avoidance response. In this study, we further explored the induction mechanism of the cold-avoidance response in the liverwort Marchantia polymorpha and examined the relationship between changes in the amount of phot and the induction of the cold-avoidance response. The switch between the accumulation and avoidance responses occurs at a so-called 'transitional' light intensity. Our physiological experiments revealed that a cold-mediated decrease in the transitional light intensity leads to the induction of the cold-avoidance response. While artificial overexpression of phot decreased the transitional light intensity as much as cold treatment did, the amount of endogenous phot was not increased by cold treatment in wild-type M. polymorpha. Taken together, these findings show that the cold-avoidance response is initiated by a cold-mediated reduction of the transitional light intensity, independent of the amount of endogenous phot. This study provides a clue to understanding the mechanism underlying the switch in direction of chloroplast relocation in response to light and temperature.


Assuntos
Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Fototropinas/metabolismo , Cloroplastos/ultraestrutura , Temperatura Baixa , Genes de Plantas , Luz , Marchantia/genética , Marchantia/metabolismo , Marchantia/efeitos da radiação , Movimento/efeitos da radiação , Fototropinas/genética , Fototropismo , Plantas Geneticamente Modificadas , Regulação para Cima
10.
Proc Natl Acad Sci U S A ; 117(22): 12452-12463, 2020 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-32404426

RESUMO

Plastid isoprenoid-derived carotenoids serve essential roles in chloroplast development and photosynthesis. Although nearly all enzymes that participate in the biosynthesis of carotenoids in plants have been identified, the complement of auxiliary proteins that regulate synthesis, transport, sequestration, and degradation of these molecules and their isoprenoid precursors have not been fully described. To identify such proteins that are necessary for the optimal functioning of oxygenic photosynthesis, we screened a large collection of nonphotosynthetic (acetate-requiring) DNA insertional mutants of Chlamydomonas reinhardtii and isolated cpsfl1 The cpsfl1 mutant is extremely light-sensitive and susceptible to photoinhibition and photobleaching. The CPSFL1 gene encodes a CRAL-TRIO hydrophobic ligand-binding (Sec14) domain protein. Proteins containing this domain are limited to eukaryotes, but some may have been retargeted to function in organelles of endosymbiotic origin. The cpsfl1 mutant showed decreased accumulation of plastidial isoprenoid-derived pigments, especially carotenoids, and whole-cell focused ion-beam scanning-electron microscopy revealed a deficiency of carotenoid-rich chloroplast structures (e.g., eyespot and plastoglobules). The low carotenoid content resulted from impaired biosynthesis at a step prior to phytoene, the committed precursor to carotenoids. The CPSFL1 protein bound phytoene and ß-carotene when expressed in Escherichia coli and phosphatidic acid in vitro. We suggest that CPSFL1 is involved in the regulation of phytoene synthesis and carotenoid transport and thereby modulates carotenoid accumulation in the chloroplast.


Assuntos
Carotenoides/metabolismo , Chlamydomonas reinhardtii/crescimento & desenvolvimento , Cloroplastos/metabolismo , Proteínas de Plantas/metabolismo , Chlamydomonas reinhardtii/classificação , Chlamydomonas reinhardtii/genética , Chlamydomonas reinhardtii/metabolismo , Cloroplastos/química , Cloroplastos/genética , Fotossíntese , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Domínios Proteicos
11.
Proc Natl Acad Sci U S A ; 117(17): 9613-9620, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32284406

RESUMO

In plants and animals, nucleotide-binding leucine-rich repeat (NLR) proteins are intracellular immune sensors that recognize and eliminate a wide range of invading pathogens. NLR-mediated immunity is known to be modulated by environmental factors. However, how pathogen recognition by NLRs is influenced by environmental factors such as light remains unclear. Here, we show that the agronomically important NLR Rpi-vnt1.1 requires light to confer disease resistance against races of the Irish potato famine pathogen Phytophthora infestans that secrete the effector protein AVRvnt1. The activation of Rpi-vnt1.1 requires a nuclear-encoded chloroplast protein, glycerate 3-kinase (GLYK), implicated in energy production. The pathogen effector AVRvnt1 binds the full-length chloroplast-targeted GLYK isoform leading to activation of Rpi-vnt1.1. In the dark, Rpi-vnt1.1-mediated resistance is compromised because plants produce a shorter GLYK-lacking the intact chloroplast transit peptide-that is not bound by AVRvnt1. The transition between full-length and shorter plant GLYK transcripts is controlled by a light-dependent alternative promoter selection mechanism. In plants that lack Rpi-vnt1.1, the presence of AVRvnt1 reduces GLYK accumulation in chloroplasts counteracting GLYK contribution to basal immunity. Our findings revealed that pathogen manipulation of chloroplast functions has resulted in a light-dependent immune response.


Assuntos
Cloroplastos/microbiologia , Regulação da Expressão Gênica de Plantas/imunologia , Luz , Proteínas NLR/metabolismo , Phytophthora infestans/metabolismo , Proteínas de Plantas/metabolismo , Agrobacterium/metabolismo , Animais , Cloroplastos/metabolismo , Escherichia coli/metabolismo , Proteínas Fúngicas , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Inativação Gênica , Microscopia Confocal , Proteínas NLR/genética , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Proteínas de Plantas/genética , Plântula , Solanum tuberosum/metabolismo , Solanum tuberosum/microbiologia , Tabaco/metabolismo , Tabaco/microbiologia , Técnicas do Sistema de Duplo-Híbrido
12.
Nat Commun ; 11(1): 1662, 2020 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-32245955

RESUMO

The proteasome is an essential protein-degradation machinery in eukaryotic cells that controls protein turnover and thereby the biogenesis and function of cell organelles. Chloroplasts import thousands of nuclear-encoded precursor proteins from the cytosol, suggesting that the bulk of plastid proteins is transiently exposed to the cytosolic proteasome complex. Therefore, there is a cytosolic equilibrium between chloroplast precursor protein import and proteasomal degradation. We show here that a shift in this equilibrium, induced by mild genetic proteasome impairment, results in elevated precursor protein abundance in the cytosol and significantly increased accumulation of functional photosynthetic complexes in protein import-deficient chloroplasts. Importantly, a proteasome lid mutant shows improved photosynthetic performance, even in the absence of an import defect, signifying that functional precursors are continuously degraded. Hence, turnover of plastid precursors in the cytosol represents a mechanism to constrain thylakoid membrane assembly and photosynthetic electron transport.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Cloroplastos/metabolismo , Complexo de Proteínas do Centro de Reação Fotossintética/metabolismo , Complexo de Endopeptidases do Proteassoma/genética , Proteínas de Cloroplastos/metabolismo , Citosol/metabolismo , Mutação , Fotossíntese , Plantas Geneticamente Modificadas , Complexo de Endopeptidases do Proteassoma/metabolismo , Precursores de Proteínas/metabolismo , Proteólise , Estresse Fisiológico
13.
Plant Mol Biol ; 103(4-5): 457-471, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32274640

RESUMO

KEY MESSAGE: In this manuscript, we disclosed the influence of light on the accumulation of storage reserves in B. napus embryos.1.Light induced the gene expression in the developing embryos of B. napus.2.Light promoted the starch synthesis in chloroplasts of B. napus embryos.3.Light enhanced the metabolic activity of storage reserve synthesis in B. napus embryos. Light influences the accumulation of storage reserves in embryos, but the molecular mechanism was not fully understood. Here, we monitored the effects of light on reserve biosynthesis in Brassica napus by comparing embryos from siliques grown in normal light conditions to those that were shaded or masked (i.e., darkened completely). Masked embryos developed more slowly, weighed less, and contained fewer proteins and lipids than control embryos. They also had fewer and smaller oil bodies than control embryos and lacked chloroplasts, where starch grains are usually synthesized. The levels of most amino acids, carbohydrates, and fatty acids were higher in masked embryos than in control or shaded embryos, whereas the levels of these metabolites in the masked endosperms were lower than those in control and shaded endosperm. Transcriptome analysis indicated that genes involved in photosynthesis (42 genes), amino acid biosynthesis (51 genes), lipid metabolism (61 genes), and sugar transport (13 genes) were significantly repressed in masked embryos. Our results suggest that light contributes to reserve accumulation in embryos by inducing the expression of metabolic genes, thereby enhancing the biosynthesis of storage reserves.


Assuntos
Brassica napus/embriologia , Brassica napus/genética , Brassica napus/efeitos da radiação , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , Sementes/genética , Sementes/efeitos da radiação , Aminoácidos/metabolismo , Brassica napus/crescimento & desenvolvimento , Metabolismo dos Carboidratos , Clorofila/análise , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Endosperma/metabolismo , Endosperma/efeitos da radiação , Ácidos Graxos/metabolismo , Perfilação da Expressão Gênica , Metabolismo dos Lipídeos , Fotossíntese , Óleos Vegetais/metabolismo , Proteínas de Plantas/genética , Sementes/citologia , Sementes/crescimento & desenvolvimento , Amido/biossíntese , Transcriptoma
14.
Integr Comp Biol ; 60(1): 43-56, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32294176

RESUMO

Several species of sacoglossan sea slugs are able to sequester chloroplasts from algae and incorporate them into their cells. However, the ability to maintain functional "stolen" plastids (kleptoplasts) can vary significantly within the Sacoglossa, giving species different capacities to withstand periods of food shortage. The present study provides an insight on the comparative shifts experienced by the lipidome of two sacoglossan sea slug species, Elysia viridis (long-term retention of functional chloroplasts) and Placida dendritica (retention of non-functional chloroplasts). A hydrophilic interaction liquid chromatography-mass spectrometry approach was employed to screen the lipidome of specimens from both species feeding on the macroalga Codium tomentosum and after 1-week of starvation. The lipidome of E. viridis was generally unaffected by the absence of food, while that of P. dendritica varied significantly. The retention of functional chloroplasts by E. viridis cells allows this species to endure periods of food shortage, while in P. dendritica a significant reduction in the amount of main lipids was the consequence of the consumption of its own mass to endure starvation. The large proportion of ether phospholipids (plasmalogens) in both sea slug species suggests that these compounds may play a key role in chloroplast incorporation in sea slug cells and/or be involved in the reduction of the oxidative stress resulting from the presence of kleptoplasts.


Assuntos
Clorófitas/fisiologia , Cloroplastos/metabolismo , Privação de Alimentos , Gastrópodes/metabolismo , Lipidômica , Alga Marinha/fisiologia , Animais , Especificidade da Espécie
15.
Ecotoxicol Environ Saf ; 195: 110469, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32179235

RESUMO

To explore the mechanism of how lead (Pb) and cadmium (Cd) stress affects photosynthesis of mulberry (Morus alba L.), we looked at the effects of different concentrations of Pb and Cd stress (at 100 and 200 µmol L-1), which are two heavy metal elements, on leaf chlorophyll (Chl), photosynthesis gas exchange, Chl fluorescence, and reactive oxygen species (ROS) metabolism in mulberry leaves. The results showed that higher concentrations of Pb and Cd reduced leaf Chl content, especially in Chl a where content was more sensitive than in Chl b. Under Pb and Cd stress, the photosynthetic carbon assimilation capacity of mulberry leaves was reduced, which was a consequence of combined limitations of stomatal and non-stomatal factors. The main non-stomatal factors were decreased photosystem II (PSII) and photosystem I (PSI) activity and carboxylation efficiency (CE). Damage to the donor side of the PSII reaction center was greater than the acceptor side. After being treated with 100 µmol L-1 of Pb and Cd, mulberry leaves continued to be able to dissipate excess excitation energy by starting non-photochemical quenching (NPQ), but when Pb and Cd concentrations were increased to 200 µmol L-1, the protection mechanism that depends on NPQ was impaired. Excessive excitation energy from chloroplasts promoted a great increase of ROS, such as superoxide anion (O2•-) and H2O2. Moreover, under high Pb and Cd stress, superoxide dismutase (SOD) and ascorbate peroxidase (APX) were also inhibited to some extent, and excessive ROS also resulted in a significantly higher degree of oxidative damage. Compared with Cd, the effect of Pb stress at the same concentration level displayed a significantly lower impact on Chl content, photosynthetic carbon assimilation, and stomatal conductance. Meanwhile, Pb stress mainly damaged activity of the oxygen-evolving complex (OEC) located on PSII donor side, but it reduced the electronic pressure on the PSII acceptor side and PSI. Furthermore, under Pb stress, the NPQ, SOD, and APX activity were all significantly higher than those under Cd stress. Thus under Pb stress, the degree of photoinhibition and oxidative damage of PSII and PSI in mulberry leaves were significantly lower than under Cd stress.


Assuntos
Cádmio/toxicidade , Chumbo/toxicidade , Morus/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Ascorbato Peroxidases/metabolismo , Clorofila/metabolismo , Cloroplastos/efeitos dos fármacos , Cloroplastos/metabolismo , Peróxido de Hidrogênio/metabolismo , Morus/enzimologia , Morus/metabolismo , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Plântula/efeitos dos fármacos , Plântula/metabolismo , Superóxido Dismutase/metabolismo
16.
Nat Commun ; 11(1): 1254, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32198392

RESUMO

Chlorophyll is indispensable for life on Earth. Dynamic control of chlorophyll level, determined by the relative rates of chlorophyll anabolism and catabolism, ensures optimal photosynthesis and plant fitness. How plants post-translationally coordinate these two antagonistic pathways during their lifespan remains enigmatic. Here, we show that two Arabidopsis paralogs of BALANCE of CHLOROPHYLL METABOLISM (BCM) act as functionally conserved scaffold proteins to regulate the trade-off between chlorophyll synthesis and breakdown. During early leaf development, BCM1 interacts with GENOMES UNCOUPLED 4 to stimulate Mg-chelatase activity, thus optimizing chlorophyll synthesis. Meanwhile, BCM1's interaction with Mg-dechelatase promotes degradation of the latter, thereby preventing chlorophyll degradation. At the onset of leaf senescence, BCM2 is up-regulated relative to BCM1, and plays a conserved role in attenuating chlorophyll degradation. These results support a model in which post-translational regulators promote chlorophyll homeostasis by adjusting the balance between chlorophyll biosynthesis and breakdown during leaf development.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Clorofila/biossíntese , Cisteína Endopeptidases/metabolismo , Homeostase , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Biossíntese de Proteínas , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Sequência Conservada , Cisteína Endopeptidases/genética , Enzimas/metabolismo , Epistasia Genética , Regulação da Expressão Gênica de Plantas , Peptídeos e Proteínas de Sinalização Intracelular/genética , Modelos Biológicos , Folhas de Planta/genética , Estabilidade Proteica , Plântula/genética , Plântula/crescimento & desenvolvimento
17.
Cell ; 180(6): 1144-1159.e20, 2020 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-32169217

RESUMO

In eukaryotic cells, organelle biogenesis is pivotal for cellular function and cell survival. Chloroplasts are unique organelles with a complex internal membrane network. The mechanisms of the migration of imported nuclear-encoded chloroplast proteins across the crowded stroma to thylakoid membranes are less understood. Here, we identified two Arabidopsis ankyrin-repeat proteins, STT1 and STT2, that specifically mediate sorting of chloroplast twin arginine translocation (cpTat) pathway proteins to thylakoid membranes. STT1 and STT2 form a unique hetero-dimer through interaction of their C-terminal ankyrin domains. Binding of cpTat substrate by N-terminal intrinsically disordered regions of STT complex induces liquid-liquid phase separation. The multivalent nature of STT oligomer is critical for phase separation. STT-Hcf106 interactions reverse phase separation and facilitate cargo targeting and translocation across thylakoid membranes. Thus, the formation of phase-separated droplets emerges as a novel mechanism of intra-chloroplast cargo sorting. Our findings highlight a conserved mechanism of phase separation in regulating organelle biogenesis.


Assuntos
Arabidopsis/metabolismo , Transporte Proteico/fisiologia , Sistema de Translocação de Argininas Geminadas/metabolismo , Proteínas de Cloroplastos/metabolismo , Cloroplastos/metabolismo , Membranas Intracelulares/metabolismo , Proteínas de Membrana/metabolismo , Biogênese de Organelas , Organelas/metabolismo , Transição de Fase , Proteínas de Plantas/metabolismo , Tilacoides/metabolismo , Sistema de Translocação de Argininas Geminadas/fisiologia
18.
Proc Natl Acad Sci U S A ; 117(12): 6918-6927, 2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32161131

RESUMO

Singlet oxygen (1O2), the major reactive oxygen species (ROS) produced in chloroplasts, has been demonstrated recently to be a highly versatile signal that induces various stress responses. In the fluorescent (flu) mutant, its release causes seedling lethality and inhibits mature plant growth. However, these drastic phenotypes are suppressed when EXECUTER1 (EX1) is absent in the flu ex1 double mutant. We identified SAFEGUARD1 (SAFE1) in a screen of ethyl methanesulfonate (EMS) mutagenized flu ex1 plants for suppressor mutants with a flu-like phenotype. In flu ex1 safe1, all 1O2-induced responses, including transcriptional rewiring of nuclear gene expression, return to levels, such as, or even higher than, those in flu Without SAFE1, grana margins (GMs) of chloroplast thylakoids (Thys) are specifically damaged upon 1O2 generation and associate with plastoglobules (PGs). SAFE1 is localized in the chloroplast stroma, and release of 1O2 induces SAFE1 degradation via chloroplast-originated vesicles. Our paper demonstrates that flu-produced 1O2 triggers an EX1-independent signaling pathway and proves that SAFE1 suppresses this signaling pathway by protecting GMs.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Estresse Oxidativo , Substâncias Protetoras/metabolismo , Plântula/crescimento & desenvolvimento , Oxigênio Singlete/toxicidade , Tilacoides/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Cloroplastos/efeitos dos fármacos , Cloroplastos/metabolismo , Cloroplastos/patologia , Regulação da Expressão Gênica de Plantas , Luz , Mutação , Espécies Reativas de Oxigênio/metabolismo , Plântula/genética , Plântula/metabolismo , Tilacoides/efeitos dos fármacos , Tilacoides/patologia
19.
Artigo em Inglês | MEDLINE | ID: mdl-32213379

RESUMO

Cold stress is one of the most common unfavorable environmental factors affecting the growth, development, and survival of plants. The DEAD-box RNA helicases play important roles in all types of processes of RNA metabolism. However, the function of DEAD-box RNA helicase under cold stress is poorly explored in plants, especially in rice. This study reported the identification of a novel rice thermo-sensitive chlorophyll-deficient mutant, tcd33, which displayed an albino phenotype before the four-leaf stage, then withered and eventually died at 20 °C, while wild-type plants exhibited normal green coloration at 32 °C. The tcd33 seedlings also exhibited less chlorophyll contents and severe defects of chloroplast structure under 20 °C condition. Map-based cloning and complementation experiments suggested that TCD33 encodes a chloroplast-located DEAD-box RNA helicase protein. The transcript expression level of TCD33 indicated that the genes related to chlorophyll (Chl) biosynthesis, photosynthesis, and chloroplast development in tcd33 mutants were down-regulated at 20 °C, while the down-regulated genes were nearly recovered to or slightly higher than the WT level at 32 °C. Together, our results suggest that the cold-inducible TCD33 is essential for early chloroplast development and is important for cold-responsive gene regulation and cold tolerance in rice.


Assuntos
Cloroplastos/metabolismo , Resposta ao Choque Frio/genética , RNA Helicases DEAD-box/genética , Oryza/fisiologia , Proteínas de Plantas/genética , Sequência de Aminoácidos , RNA Helicases DEAD-box/química , RNA Helicases DEAD-box/metabolismo , Regulação da Expressão Gênica de Plantas , Oryza/genética , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Filogenia , Proteínas de Plantas/metabolismo , Plântula/metabolismo , Alinhamento de Sequência
20.
PLoS One ; 15(2): e0229408, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32092117

RESUMO

The chloroplast is a central part of plant cells, as this is the organelle where the photosynthesis, fixation of inorganic carbon, and other key functions related to fatty acid synthesis and amino acid synthesis occur. Since this organelle should be an integral part of any genome-scale metabolic model for a microalgae or a higher plant, it is of great interest to generate a detailed and standardized chloroplast model. Additionally, we see the need for a novel type of sub-model template, or organelle model, which could be incorporated into a larger, less specific genome-scale metabolic model, while allowing for minor differences between chloroplast-containing organisms. The result of this work is the very first standardized chloroplast model, iGR774, consisting of 788 reactions, 764 metabolites, and 774 genes. The model is currently able to run in three different modes, mimicking the chloroplast metabolism of three photosynthetic microalgae-Nannochloropsis gaditana, Chlamydomonas reinhardtii and Phaeodactylum tricornutum. In addition to developing the chloroplast metabolic network reconstruction, we have developed multiple software tools for working with this novel type of sub-model in the COBRA Toolbox for MATLAB, including tools for connecting the chloroplast model to a genome-scale metabolic reconstruction in need of a chloroplast, for switching the model between running in different organism modes, and for expanding it by introducing more reactions either related to one of the current organisms included in the model, or to a new organism.


Assuntos
Cloroplastos/genética , Biologia Computacional/métodos , Redes e Vias Metabólicas/genética , Microalgas/genética , Modelos Biológicos , Software , Chlamydomonas reinhardtii/genética , Chlamydomonas reinhardtii/metabolismo , Cloroplastos/metabolismo , Diatomáceas/genética , Diatomáceas/metabolismo , Genoma/fisiologia , Microalgas/ultraestrutura , Fotossíntese/genética
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