Intersystem photosynthetic redox signal in retrograde chloroplast-to-nucleus communication
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
PROVIDER: GSE42710 | GEO | 2015/03/23
SECONDARY ACCESSION(S): PRJNA182913
REPOSITORIES: GEO
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Project description:To analyze the impact of photosynthetic redox signals, light sources with spectral qualities that preferentially excite either Photosystem I (PSI light) or Photosystem II (PSII light) were used. The light sources have been described in (Fey et al., 2005). Strong reduction and oxidation signals were induced by light shifts from PSI to PSII light (PSI-II) and the reverse light shift (PSII-I), respectivly. The acclimation responses were monitored at 0.5, 2, 8, and 48h after a light shift. Samples taken prior to changing the light quality (0h) served as control. Keywords: photosynthesis, redox regulation, light acclimation, retrograde signalling, long term response
2009-07-30 | GSE9235 | GEO
Project description:To analyze the impact of photosynthetic redox signals, light sources with spectral qualities that preferentially excite either Photosystem I (PSI light) or Photosystem II (PSII light) were used. The light sources have been described in (Fey et al., 2005). Strong reduction and oxidation signals were induced by light shifts from PSI to PSII light (PSI-II) and the reverse light shift (PSII-I), respectivly. The acclimation responses were monitored at 0.5, 2, 8, and 48h after a light shift. Samples taken prior to changing the light quality (0h) served as control. Keywords: photosynthesis, redox regulation, light acclimation, retrograde signalling, long term response Experiments were performed with plant material corresponding to pools of at least 250-500 individuals of Arabidopsis thaliana (Col-0). To abtain healthy and unstressed plants, seedlings were initially grown for 21 days under white light (short day periods, 8-h light/16-h dark) on soil. Plants were then pre-acclimated to PSI-light for 3 days and reference samples were taken. Plants were then shifted to PSII light and tissue was harvested at the described time points. Similarly, samples were harvested before and after the reverse light shift. As additional control, plants acclimated to white light were also analyzed. RNA isolation: Leaf material was harvested and frozen in liquid N2 under the respective light source. Isolation of total RNA was performed as adapted from (Westhoff et al., 1991). Array analyses using the 3292-GST nylon array were performed as described earlier (Richly et al., 2003; Fey et al., 2005). Three independent experiments with different filters and independent cDNA probes were performed (for each timepoint).
2010-06-24 | E-GEOD-9235 | biostudies-arrayexpress
Project description:In photosynthesis, light is absorbed by the thylakoid embedded light harvesting pigment protein complexes (LHCs) that surround the photosynthetic reaction centers, photosystem II (PSII) and photosystem I (PSI). The distribution of light energy between the photosystems is balanced through state transitions1,2, which refer to the phosphorylation-dependent association of the loosely bound (L) LHCII antenna trimer either to PSII or PSI 3,4. Apart from phosphorylation, other mechanisms regulating state transitions have not been reported this far. In this study we demonstrate that lysine (Lys) acetylation of chloroplast proteins is a prerequisite for state transitions in Arabidopsis thaliana. Knock-out mutants lacking a chloroplast acetyltransferase NSI (At1g32070; AtNSI, SNAT) show selective decreases in the Lys acetylation status of several photosynthetic proteins including PSI, PSII and LHCII subunits. Fluorescence measurements revealed that changes in the wavelength of illumination do not cause state transitions in the nsi mutants even though their LHCII phosphorylation status is not defected. Furthermore, biochemical analyses of thylakoid proteins and protein complexes showed that nsi plants are not able to accumulate the phosphorylation dependent PSI-LHCII megacomplex. Our results manifest that Lys acetylation by NSI has an integral role in the regulation of state transitions in Arabidopsis.
2018-07-03 | PXD007625 | Pride
Project description:In photosynthesis, light is absorbed by the thylakoid embedded light harvesting pigment protein complexes (LHCs) that surround the photosynthetic reaction centers, photosystem II (PSII) and photosystem I (PSI). The distribution of light energy between the photosystems is balanced through state transitions1,2, which refer to the phosphorylation-dependent association of the loosely bound (L) LHCII antenna trimer either to PSII or PSI 3,4. Apart from phosphorylation, other mechanisms regulating state transitions have not been reported this far. In this study we demonstrate that lysine (Lys) acetylation of chloroplast proteins is a prerequisite for state transitions in Arabidopsis thaliana. Knock-out mutants lacking a chloroplast acetyltransferase NSI (At1g32070; AtNSI, SNAT) show selective decreases in the Lys acetylation status of several photosynthetic proteins including PSI, PSII and LHCII subunits. Fluorescence measurements revealed that changes in the wavelength of illumination do not cause state transitions in the nsi mutants even though their LHCII phosphorylation status is not defected. Furthermore, biochemical analyses of thylakoid proteins and protein complexes showed that nsi plants are not able to accumulate the phosphorylation dependent PSI-LHCII megacomplex. Our results manifest that Lys acetylation by NSI has an integral role in the regulation of state transitions in Arabidopsis.
2018-07-03 | PXD007630 | Pride
Project description:Photosystem I (PSI) is a critical component of the photosynthetic machinery in plants. Under conditions of environmental stress, PSI becomes photoinhibited, leading to redox imbalance in the chloroplast. PSI photoinhibition is caused by an increase in electron pressure within PSI, which damages the iron-sulfur centers. In this study, we investigated the effect of PSI electron acceptors on the susceptibility of PSI to photoinhibition at different CO2 concentrations in the plant environment. We also analyzed the global gene expression in plants exposed to PSI photoinhibition. PSI was photoinhibited using a specific illumination technique that inhibited PSI with minimal effect on PSII. CO2 levels neither increased nor decreased the likelihood of PSI photodamage. PSI photoinhibition, independent of CO2 levels, upregulated the genes involved in the response to iron excess in plants and downregulated the genes involved in iron deficiency. It also induced the genes of photosynthetic proteins that act as electron acceptors for PSI. We propose that PSI photoinhibition causes a release of iron from iron-sulfur centers, which initiates a retrograde signal from the chloroplast to the nucleus to modify gene expression. In addition, deprivation of CO2 from the air initiated a signal that induced flavonoid biosynthesis genes, probably via jasmonate production.
2023-11-29 | GSE242125 | GEO
Project description:Understanding how microorganisms adjust their metabolism to maintain their ability to survive to short-term environmental variations constitutes one of the major current challenges in microbial ecology. Here WH7803, the best physiologically characterized marine Synechococcus strain was submitted to modulated light/dark cycles or acclimated to continuous high-light (HL) or low-light (LL), then shifted to various stress conditions, including low (LT) or high temperature (HT), HL and ultraviolet (UV) radiations. Physiological responses were analyzed by measuring time courses of photosystem II (PSII) quantum yield, PSII repair rate, pigment and lipid content as well as whole transcriptomes. This notably revealed that cells previously acclimated to HL seem to be better prepared than LL-acclimated cells to sustain an additional light or UV stress, but not a LT stress. Indeed, LT seems to induce a synergic effect with the HL treatment, as previously observed with oxidative stress. While all tested shift conditions induced the downregulation of many photosynthetic genes, notably those encoding PSI, cytochrome b6/f and phycobilisomes, UV stress proved to be more deleterious for PSII than the other treatments, and full recovery of damaged PSII from UV stress seemed to involve the neo-synthesis of a fairly large number of PSII subunits and not just the reassembly of pre-existing subunits after D1 replacement. In contrast, genes involved in glycogen degradation and carotenoid biosynthesis pathways were more particularly upregulated in response to LT. Altogether, these experiments allowed us to identify responses common to all stresses and those more specific to a given stress, thus highlighting genes potentially involved in niche acclimation of this key component of marine ecosystems. Our data also highlighted important specificities of the stress responses compared to model freshwater cyanobacteria.
2020-06-17 | GSE146246 | GEO
Project description:Photosystem II (PSII) is the most thermally sensitive component of photosynthesis. Thermal acclimation of this complex activity is likely to be critically important to the ability of photosynthetic organisms to tolerate temperature changes in the environment. We have analysed gene expression using whole-genome microarrays and monitored alterations in physiology during acclimation of PSII to elevated growth temperature in Synechocystis sp. PCC 6803. PSII acclimation is complete within 480 minutes of exposure to elevated temperature and is associated with a highly dynamic transcriptional response. 176 genes were identified and classified into seven distinct response profile groups. Response profiles suggest the existence of an early transient phase and a sustained phase to the acclimation response. The early phase was characterised by induction of general stress response genes, including heat shock proteins, which are likely to influence PSII thermal stability. The sustained phase consisted of acclimation-specific alterations that are involved in other cellular processes. Sustained responses included genes involved in phycobillisome structure and modification, photosynthesis, respiration, lipid metabolism and motility. Approximately 60% of genes with sustained altered expression levels have no known function. The potential role of differentially expressed genes in thermotolerance and acclimation is discussed. We have characterised the acclimation physiology of selected gene ‘knockouts’ to elucidate possible gene function in the response. All mutants show lower PSII rates under normal growth conditions. Basal PSII thermotolerance was affected by mutations in clpB1, cpcC2, hspA, htpG and slr1674. Final PSII thermotolerance was affected by mutations in cpcC2, hik34, hspA and hypA1, suggesting that these gene products play roles in long-term thermal acclimation of PSII.
2010-04-09 | GSE21133 | GEO
Project description:Photosystem (PS) I and PSII enclose the reaction center subunits and cofactors responsible for the conversion of sunlight into chemical energy. In the thylakoid membrane of oxygenic photosynthetic organisms, PSII splits the water molecules and donates electrons to the electron transfer chain, and further via PSI to form NADPH. Proteins of the light-harvesting complexes (LHC) I and II are mainly associated with PSI and PSII, respectively, but also provide dynamics for the adjustments of the absorption cross-section of PSII and PSI upon changing light conditions. LHCII proteins N-terminal phosphorylation affects their interaction either with PSI or with PSII, and is a molecular mechanism present from green algae and early land plants to higher plants. The kinase STN7 is responsible for N-terminal phosphorylation of the LHCII proteins in algae and flowering plants model species, but the specific targets and role of STN7-dependent reversible phosphorylation in formation of various PS-LHC complexes in evolutionarily early land plants like mosses is poorly studied. The aim of this project was to identify the phosphorylated residues of the LHCII subunits of the moss Physcomitrium (Physcomitrella) patens (hereafter: P. patens), i.e. the LHCBM proteins, and to determine which of the phosphosites are phosphorylated by the STN7 kinase. Subsequently, the goal has been to identify which of the LHCBM subunits that are part of PSI-LHCI-LHCII complex (state complex), and of the moss-specific PSI-Large complex, are N-terminally phosphorylated in the STN7-dependent fashion.
2022-06-24 | PXD026183 | Pride
Project description:Photosystem II (PSII) is the most thermally sensitive component of photosynthesis. Thermal acclimation of this complex activity is likely to be critically important to the ability of photosynthetic organisms to tolerate temperature changes in the environment. We have analysed gene expression using whole-genome microarrays and monitored alterations in physiology during acclimation of PSII to elevated growth temperature in Synechocystis sp. PCC 6803. PSII acclimation is complete within 480 minutes of exposure to elevated temperature and is associated with a highly dynamic transcriptional response. 176 genes were identified and classified into seven distinct response profile groups. Response profiles suggest the existence of an early transient phase and a sustained phase to the acclimation response. The early phase was characterised by induction of general stress response genes, including heat shock proteins, which are likely to influence PSII thermal stability. The sustained phase consisted of acclimation-specific alterations that are involved in other cellular processes. Sustained responses included genes involved in phycobillisome structure and modification, photosynthesis, respiration, lipid metabolism and motility. Approximately 60% of genes with sustained altered expression levels have no known function. The potential role of differentially expressed genes in thermotolerance and acclimation is discussed. We have characterised the acclimation physiology of selected gene ‘knockouts’ to elucidate possible gene function in the response. All mutants show lower PSII rates under normal growth conditions. Basal PSII thermotolerance was affected by mutations in clpB1, cpcC2, hspA, htpG and slr1674. Final PSII thermotolerance was affected by mutations in cpcC2, hik34, hspA and hypA1, suggesting that these gene products play roles in long-term thermal acclimation of PSII. Gene expression levels were compared during a time-course (up to 8 hours) of thermal acclimation (from 25C to 38C) of a wild-type strain grown under continuous illumination and bubbled with CO2 -enriched air. Up to four independent biological replicates were generated and analysed. Each array: replicate matched time-point vs. 0hr control.
2010-04-09 | E-GEOD-21133 | biostudies-arrayexpress
Project description:Series of 6 repetitions of hybridization of treatment (PSII) and control (PSI) each. Comparison of plants grown under PSII-specific light versus plants grown under PSI-specific light. E. Richly et al., EMBO Rep. 4 (2003), pp. 491–498 Keywords: repeat sample
2005-01-01 | GSE1169 | GEO