| 1. |
- Aigner, Harald, 1973-
(författare)
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Characterization of FtsH proteases in the annual plant Arabidopsis thaliana
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background FtsH is an ATP-dependent membrane-bound metalloprotease. A. thaliana contains 12 FtsH proteases localized in membranes of chloroplasts and mitochondria where they form homo- or hetero-hexameric complexes. FtsH11 – the main subject of this thesis – is located in the chloroplast envelope. Methods Field studies with A. thaliana to determine Darwinian fitness. A growth under outdoor conditions often allows discovering of phenotypes that are unascertainable in the controlled environment of growth chambers. Proteomic methods to discover fragments of substrate proteins (limited proteolysis) and changes in the proteome of FtsH protease deficient mutants. Results ftsh11 has increased amount of: RuBisCO activase, several Calvin cycle enzymes, two enzymes involved in starch synthesis and some chaperons. Some of those enzymes have been identified as possible substrates of FtsH11. Under long photoperiods ftsh11 develops a chlorotic phenotype accompanied by decreasing NADP+/NADPH ratio and increase of ROS damaged proteins.
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| 2. |
- Aigner, Harald, 1973-, et al.
(författare)
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FtsH11 protease is required for Arabidopsis thaliana to adapt to gtowth in continuous light
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Continuous light can increase greenhouse food production; however, some of the most important greenhouse horticulture crops are not able to adapt to long photoperiods. Here, we provide evidence that knock-out of the FtsH11 protease causes molecular differences that prevent Arabidopsis thaliana to adapt to prolonged photoperiods. Previously this protease had been shown to be critical for thermotolerance (Chen et al. 2006). We demonstrate that knock-out mutants deficient of FtsH11 develop chlorosis when shifted to continuous light. When grown under normal growth conditions and short days, ftsh11 displayed changes in protein amount of chloroplast proteins involved in the photosynthetic light reaction and the Calvin cycle as well as of the FtsH12 protease. The proteomic changes are accompanied by reduced non-photochemical quenching and faster state transition. A shift to continuous light further enhanced these effects and induced morphological changes of the chloroplast and chlorosis. No changes in the mitochondrial proteome were observed between wild type and ftsh11.
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| 3. |
- Allahverdiyeva, Yagut, et al.
(författare)
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NordAqua, a Nordic Center of Excellence to develop an algae-based photosynthetic production platform
- 2021
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Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 173:2, s. 507-513
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Tidskriftsartikel (refereegranskat)abstract
- NordAqua is a multidisciplinary Nordic Center of Excellence funded by NordForsk Bioeconomy program (2017–2022). The research center promotes Blue Bioeconomy and endeavours to reform the use of natural resources in a environmentally sustainable way. In this short communication, we summarize particular outcomes of the consortium. The key research progress of NordAqua includes (1) improving of photosynthetisis, (2) developing novel photosynthetic cell factories that function in a “solar-driven direct CO2 capture to target bioproducts” mode, (3) promoting the diversity of Nordic cyanobacteria and algae as an abundant and resilient alternative for less sustainable forest biomass and for innovative production of biochemicals, and (4) improving the bio-based wastewater purification and nutrient recycling technologies to provide new tools for integrative circular economy platforms.
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| 4. |
- Alling, Teodor, et al.
(författare)
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Nordic microalgae produce biostimulant for the germination of tomato and barley seeds
- 2023
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Microalgal biomass may have biostimulating effects on plants and seeds due to its phytohormonal content, and harnessing this biostimulating effect could contribute to sustainable agriculture. Two Nordic strains of freshwater microalgae species Chlorella vulgaris and Scenedesmus obliquus were each cultivated in a photobioreactor receiving untreated municipal wastewater. The algal biomass and the supernatant after algal cultivation were tested on tomato and barley seeds for biostimulating effects. Intact algal cells, broken cells, or harvest supernatant were applied to the seeds, and germination time, percentage and germination index were evaluated. Seeds treated with C. vulgaris, in particular intact cells or supernatant, had up to 25 percentage units higher germination percentage after 2 days and an overall significantly faster germination time (germinated on average between 0.5 and 1 day sooner) than seeds treated with S. obliquus or the control (water). The germination index was higher in C. vulgaris treatments than in the control for both tomato and barley, and this was observed for both broken and intact cells as well as supernatant. The Nordic strain of C. vulgaris cultivated in municipal wastewater thus shows potential for use as biostimulant in agriculture, adding novel economic and sustainability benefits.
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| 5. |
- Angelcheva, Liudmila, et al.
(författare)
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Metabolomic analysis of extreme freezing tolerance in Siberian spruce (Picea obovata)
- 2014
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 204:3, s. 545-555
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Tidskriftsartikel (refereegranskat)abstract
- Siberian spruce (Picea obovata) is one of several boreal conifer species that can survive at extremely low temperatures (ELTs). When fully acclimated, its tissues can survive immersion in liquid nitrogen. Relatively little is known about the biochemical and biophysical strategies of ELT survival. We profiled needle metabolites using gas chromatography coupled with mass spectrometry (GC-MS) to explore the metabolic changes that occur during cold acclimation caused by natural temperature fluctuations. In total, 223 metabolites accumulated and 52 were depleted in fully acclimated needles compared with pre-acclimation needles. The metabolite profiles were found to develop in four distinct phases, which are referred to as pre-acclimation, early acclimation, late acclimation and fully acclimated. Metabolite changes associated with carbohydrate and lipid metabolism were observed, including changes associated with increased raffinose family oligosaccharide synthesis and accumulation, accumulation of sugar acids and sugar alcohols, desaturation of fatty acids, and accumulation of digalactosylglycerol. We also observed the accumulation of protein and nonprotein amino acids and polyamines that may act as compatible solutes or cryoprotectants. These results provide new insight into the mechanisms of freezing tolerance development at the metabolite level and highlight their importance in rapid acclimation to ELT in P.obovata.
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| 6. |
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| 7. |
- Chen, Que, et al.
(författare)
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Combining retinal-based and chlorophyll-based (oxygenic) photosynthesis : Proteorhodopsin expression increases growth rate and fitness of a Delta PSI strain of Synechocystis sp. PCC6803
- 2019
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Ingår i: Metabolic engineering. - : Elsevier. - 1096-7176 .- 1096-7184. ; 52, s. 68-76
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Tidskriftsartikel (refereegranskat)abstract
- To fill the "green absorption gap", a green absorbing proteorhodopsin was expressed in a PSI-deletion strain (Delta PSI) of Synechocystis sp. PCC6803. Growth-rate measurements, competition experiments and physiological characterization of the proteorhodopsin-expressing strains, relative to the Delta PSI control strain, allow us to conclude that proteorhodopsin can enhance the rate of photoheterotrophic growth of Delta PSI Synechocystis strain. The physiological characterization included measurement of the amount of residual glucose in the spent medium and analysis of oxygen uptake- and production rates. To explore the use of solar radiation beyond the PAR region, a red-shifted variant Proteorhodopsin-D212N/F234S was expressed in a retinal-deficient PSI-deletion strain (Delta PSI/Delta SynACO). Via exogenous addition of retinal analogue an infrared absorbing pigment (maximally at 740 nm) was reconstituted in vivo. However, upon illumination with 746 nm light, it did not significantly stimulate the growth (rate) of this mutant. The inability of the proteorhodopsin-expressing Delta PSI strain to grow photoautotrophically is most likely due to a kinetic rather than a thermodynamic limitation of its NADPH-dehydrogenase in NADP(+)-reduction.
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| 8. |
- Chen, Que, et al.
(författare)
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Functional Expression of Gloeobacter Rhodopsin in PSI-Less Synechocystis sp. PCC6803
- 2019
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Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media S.A.. - 2296-4185. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- The approach of providing an oxygenic photosynthetic organism with a cyclic electron transfer system, i.e., a far-red light-driven proton pump, is widely proposed to maximize photosynthetic efficiency via expanding the absorption spectrum of photosynthetically active radiation. As a first step in this approach, Gloeobacter rhodopsin was expressed in a PSI-deletion strain of Synechocystis sp. PCC6803. Functional expression of Gloeobacter rhodopsin, in contrast to Proteorhodopsin, did not stimulate the rate of photoheterotrophic growth of this Synechocystis strain, analyzed with growth rate measurements and competition experiments. Nevertheless, analysis of oxygen uptake and-production rates of the Gloeobacter rhodopsin-expressing strains, relative to the 1 PSI control strain, confirm that the proton-pumping Gloeobacter rhodopsin provides the cells with additional capacity to generate proton motive force. Significantly, expression of the Gloeobacter rhodopsin did modulate levels of pigment formation in the transgenic strain.
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| 9. |
- Cheregi, Otilia, et al.
(författare)
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Antibiotic Disc Assay for Measuring Cell Wall Function in Synechocystis sp. PCC6803
- 2016
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Ingår i: Bio-protocol. - 2331-8325. ; 6:24
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Tidskriftsartikel (refereegranskat)abstract
- This protocol describes how to investigate the integrity of the outer cell wall in thecyanobacterium Synechocystis sp. PCC6803 using antibiotics. It is adapted to the agar diffusion test(Bauer et al., 1966), in which filter paper discs impregnated with specified concentrations of antibioticswere placed on agar plates inoculated with bacteria. The antibiotics we tested, interfering with thebiosynthesis/function of bacterial cell walls, will diffuse into the agar and produce a zone ofcyanobacterial growth inhibition around the disc(s). The size of the inhibition zone reflects the sensitivityof the strain to the action of antibiotics, e.g., a mutation in a protein functioning within the cell wall or itsconstruction would render the mutant strain more sensitive to the respective antibiotic. The method hasproven to be useful for phenotyping a mutant of Synechocystis sp. PCC6803 lacking all three genesencoding Deg proteases. Deletion of these ATP-independent serine proteases was shown to haveimpact on the outer cell layers of Synechocystis cells.
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| 10. |
- Cheregi, Otilia, et al.
(författare)
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Inactivation of the Deg protease family in the cyanobacterium Synechocystis sp. PCC 6803 has impact on the outer cell layers
- 2015
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Ingår i: Journal of Photochemistry and Photobiology. B. - : Elsevier. - 1011-1344 .- 1873-2682. ; , s. 383-394
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Tidskriftsartikel (refereegranskat)abstract
- The serine type Deg/HtrA proteases are distributed in a wide range of organisms from Escherichia coli to humans. The cyanobacterium Synechocystis sp. PCC 6803 possesses three Deg protease orthologues: HtrA, HhoA and HhoB. Previously we compared Synechocystis 6803 wild type cells exposed to mild or severe stress conditions with a mutant lacking all three Deg proteases and demonstrated that stress had strong impact on the proteomes and metabolomes [1]. To identify the biochemical processes, which this protease family is involved in, here we compared Synechocystis sp. PCC 6803 wild type cells with a mutant lacking all three Deg proteases grown under normal growth conditions (30 °C and 40 μmol photons m−2 s−1). Deletion of the Deg proteases lead to the down-regulation of proteins related to the biosynthesis of outer cell layers (e.g. the GDP mannose 4,6-dehydratase) and affected protein secretion. During the late growth phase of the culture Deg proteases were found to be secreted to the extracellular medium of the Synechocystis sp. PCC 6803 wild type strain. While cyanobacterial Deg proteases seem to act mainly in the periplasmic space, deletion of the three proteases influences the proteome and metabolome of the whole cell. Impairments in the outer cell layers of the triple mutant might explain the higher sensitivity toward light and oxidative stress, which was observed earlier by Barker and coworkers [2].
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