Isolation and molecular characterisation of Dunaliella tertiolecta with truncated light-harvesting antenna for enhanced photosynthetic efficiency.
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ABSTRACT:
ORGANISM(S): Dunaliella tertiolecta
PROVIDER: GSE129614 | GEO | 2020/06/30
REPOSITORIES: GEO
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Project description:Isolation and molecular characterisation of Dunaliella tertiolecta with truncated light-harvesting antenna for enhanced photosynthetic efficiency.
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Project description:Photoprotective non-photochemical quenching (NPQ) represents an effective way to dissipate the light energy absorbed in excess by most phototrophs. It is often claimed that NPQ formation/relaxation kinetics are determined by xanthophyll composition. We, however, found that, for the alveolate alga Chromera velia, this is not the case. In the present paper, we investigated the reasons for the constitutive high rate of quenching displayed by the alga by comparing its light harvesting strategies with those of a model phototroph, the land plant Spinacia oleracea. Experimental results and in silico studies support the idea that fast quenching is due not to xanthophylls, but to intrinsic properties of the Chromera light harvesting complex (CLH) protein, related to amino acid composition and protein folding. The pKa for CLH quenching was shifted by 0.5 units to a higher pH compared with higher plant antennas (light harvesting complex II; LHCII). We conclude that, whilst higher plant LHCIIs are better suited for light harvesting, CLHs are 'natural quenchers' ready to switch into a dissipative state. We propose that organisms with antenna proteins intrinsically more sensitive to protons, such as C. velia, carry a relatively high concentration of violaxanthin to improve their light harvesting. In contrast, higher plants need less violaxanthin per chlorophyll because LHCII proteins are more efficient light harvesters and instead require co-factors such as zeaxanthin and PsbS to accelerate and enhance quenching.
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Project description:Chlorophylls and bacteriochlorophylls, together with carotenoids, serve, noncovalently bound to specific apoproteins, as principal light-harvesting and energy-transforming pigments in photosynthetic organisms. In recent years, enormous progress has been achieved in the elucidation of structures and functions of light-harvesting (antenna) complexes, photosynthetic reaction centers and even entire photosystems. It is becoming increasingly clear that light-harvesting complexes not only serve to enlarge the absorption cross sections of the respective reaction centers but are vitally important in short- and long-term adaptation of the photosynthetic apparatus and regulation of the energy-transforming processes in response to external and internal conditions. Thus, the wide variety of structural diversity in photosynthetic antenna "designs" becomes conceivable. It is, however, common for LHCs to form trimeric (or multiples thereof) structures. We propose a simple, tentative explanation of the trimer issue, based on the 2D world created by photosynthetic membrane systems.
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Project description:Palmella stage is critical for some unicellular algae to survive in extreme environment conditions. The halotolerant algae Dunaliella salina is a good single-cell model for studying plant adaptation to high salinity. We found 35 salinity-responsive phosphoproteins were involved in multiple signaling and metabolic pathways upon palmella formation. The patterns of protein accumulation exhibited changes, including dynamics of cytoskeleton and cell membrane curvature, accumulation and transport of exopolycsccharides, photosynthesis and energy supplying (i.e. photosystem II stability and activity, cyclic electron transport, photorespiration, and C4 pathway), nuclear/chloroplastic gene expression regulation and protein processing, reactive oxygen species homeostasis, and salt signaling transduction. To our knowledge, this study of protein post-translational modifications regulation toward understanding the mechanism of algae palmella formation has not been reported before.
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Project description:This study aims at investigating the gene expression profile of thermogenic skunk cabbage (Symplocarpus renifolius). Using Super-SAGE, we compared the gene expression profile of different developmental stages of skunk cabbage spadices. To obtain the SuperSAGE libraries, we followed the original SuperSAGE protocol described by Matsumura and colleagues (Matsumura et al., 2003) with some modification. Total RNA of spadices in different developmental stage (immature, female, bisexual, and male) were isolated using RNAiso reagent. The SuperSAGE library was directly sequenced with a large-scale pyrosequencing method.
2011-12-22 | E-GEOD-29852 | biostudies-arrayexpress
Project description:This study aims at investigating the gene expression profile of Arabidopsis ppi2-1 mutant. Using Super-SAGE, we compared the gene expression profile of ppi2-1 mutant with that of wild-type Arabidopsis. To obtain the SuperSAGE libraries, we followed the original SuperSAGE protocol described by Matsumura and colleagues (Matsumura et al., 2003) with some modification. Total RNA was isolated from the 3rd to 6th leaves of Ws and the ppi2-1 mutant using RNAiso reagent. The SuperSAGE library was directly sequenced with a large-scale pyrosequencing method.
2008-08-08 | E-GEOD-12325 | biostudies-arrayexpress
Project description:Algae of the genus Dunaliella are known to be able to grow in a wide range of salinities. To investigate which genes may be important for growth under extremely low or high salinities, a survey of the Dunaliella sp. transcriptome was performed by microarray analysis. For the cDNA microarray 778 expressed sequence tags (ESTs) were generated from a cDNA library of Dunaliella sp. The cDNA microarray was used to compare the transcription profile of cells that were acclimated to extreme saline conditions (0.08 M and 4.5 M NaCl) with the transcription profile of cells acclimated to an intermediate salinity at 1.5 M NaCl. The comparative microarray analysis indicated that 211 out of the 778 ESTs differed in their expression levels more than two-fold in cells grown at extreme different salinity when compared to cells grown at intermediate salinity (1.5M NaCl). The sequences of these 211 cDNAs were classified into 169 non-redundant gene clusters. Of these genes, the expression of 36 genes was increased and 69 genes were suppressed in cells grown at low salinity. The expression of 49 genes was increased and 85 genes were suppressed in cells grown at high salinity. One-hundred thirty four genes have been revealed to show up- and down-regulation by high salinity (4.5M NaCl). Of the high salinity-regulated genes 52% were also influenced by low salinity (0.08M NaCl), revealing a dense overlap between low and high salt responses. Only 35 genes are regulated independently by low salt condition. Strong relationships, however, were observed in the expression of these extreme salinity-responsive genes based on Venn diagram analysis, which found 70 genes that responded to these two salinity conditions. Refined expression analysis using gene-specific primers and real-time PCR for selected transcripts was in agreement with microarray results for most genes tested. This study provides the first large-scale survey of the transcriptome in the microalga Dunaliella sp. and it provides a platform for further functional investigation of differentially expressed genes in Dunaliella. Keywords: Low salt(0.08M NaCl) or high salt(4.5M NaCl)-acclimated cells
2010-01-01 | GSE10271 | GEO
Project description:How light energy is harvested in a natural photosynthetic membrane through energy transfer is closely related to the stoichiometry and arrangement of light harvesting antenna proteins in the membrane. The specific photosynthetic architecture facilitates a rapid and efficient energy transfer among the light harvesting proteins (LH2 and LH1) and to the reaction center. Here we report the identification of linear aggregates of light harvesting proteins, LH2, in the photosynthetic membranes under ambient conditions by using atomic force microscopy (AFM) imaging and spectroscopic analysis. Our results suggest that the light harvesting protein, LH2, can exist as linear aggregates of 4 +/- 2 proteins in the photosynthetic membranes and that the protein distributions are highly heterogeneous. In the photosynthetic membranes examined in our measurements, the ratio of the aggregated to the nonaggregated LH2 proteins is about 3:1 to 5:1 depending on the intensity of the illumination used during sample incubation and on the bacterial species. AFM images further identify that the LH2 proteins in the linear aggregates are monotonically tilted at an angle 4 +/- 2 degrees from the plane of the photosynthetic membranes. The aggregates result in red-shifted absorption and emission spectra that are measured using various mutant membranes, including an LH2 knockout, LH1 knockout, and LH2 at different population densities. Measuring the fluorescence lifetimes of purified LH2 and LH2 in membranes, we have observed that the LH2 proteins in membranes exhibit biexponential lifetime decays whereas the purified LH2 proteins gave single exponential lifetime decays. We attribute that the two lifetime components originate from the existence of both aggregated and nonaggregated LH2 proteins in the photosynthetic membranes.
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Project description:Illumina HiseqTM2000 RNA-sequencing of Dunaliella salina under nitrogen deprivation condition was performed.
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