Cadmium triggers an integrated reprogramming of the metabolism of Synechocystis PCC6803, under the control of the Slr1738 regulator

Houot, Laetitia; Floutier, Martin; Marteyn, Benoît; Michaut, Magali; Picciocchi, Antoine; Legrain, Pierre; Aude, Jean-Christophe; Cassier‐Chauvat, Corinne; Chauvat, Franck

doi:10.1186/1471-2164-8-350

Cited by 84 publications

(94 citation statements)

References 65 publications

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“…In this study, DF/PF was shown to be the best phenomenological stress parameter: after only 5 h of exposure to DCMU and MV, a 50% reduction (compared to the control) was measured in the most intoxicated areas of leaves ( Figure 6). The effect of these chemicals is even more evident after 72 h. In addition, the effects of copper and cadmium significantly decreased the value of DF/PF at this time point, which is quite expected due to the wide spectrum of toxic action of the selected metals on the photosynthetic apparatus [29] and various metabolic processes [27,30].…”

Section: Discussionmentioning

confidence: 93%

“…Cadmium interferes with the oxygen-evolving complex in PSII, the plastoquinone pool, and ribulose-1,5-bisphosphate carboxylase oxygenase (RubisCo) synthesis [28,29]. It is not a redox active-transition metal, but can indirectly expedite ROS production by substituting an essential micronutrient (e.g., disturbing Fe homeostasis; [30]) or binding non-specifically to thiol groups, thereby disturbing various metabolic processes [31].…”

Section: Introductionmentioning

confidence: 99%

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Delayed fluorescence imaging of photosynthesis inhibitor and heavy metal induced stress in potato

2012

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Early chemical-induced stress in Solanum tuberosum leaves was visualized using delayed fluorescence (DF) imaging. The ability to detect spatially heterogeneous responses of plant leaves exposed to several toxicants using delayed fluorescence was compared to prompt fluorescence (PF) imaging and the standard maximum fluorescence yield of PSII measurements (Fv/Fm). The toxicants used in the study were two photosynthesis inhibitors (herbicides), 100 µM methyl viologen (MV) and 140 µM diuron (DCMU), and two heavy metals, 100 µM cadmium and 100 µM copper. The exposure times were 5 and 72 h. Significant photosynthesis-inhibitor effects were already visualized after 5 h. In addition, a significant reduction in the DF/PF index was measured in DCMU- and MV-treated leaves after 5 h. In contrast, only DCMU-treated leaves exhibited a significant decrease in Fv/Fm after 5 h. All treatments resulted in a significant decrease in the DF/PF parameter after 72 h of exposure, when only MV and Cd treatment resulted in visible symptoms. Our study highlights the power of delayed fluorescence imaging. Abundant quantifiable spatial information was obtained with the instrumental setup. Delayed fluorescence imaging has been confirmed as a very responsive and useful technique for detecting stress induced by photosynthesis inhibitors or heavy metals.

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Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Delayed fluorescence imaging of photosynthesis inhibitor and heavy metal induced stress in potato

2012

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“…WH7803, in much the same way as what has been observed in the freshwater Synechocystis sp. PCC 6803 in response to approximately millimolar H 2 O 2 concentrations (Li et al, 2004;Houot et al, 2007). Moreover, global transcriptomic data clearly indicated that H 2 O 2 and MV induced similar transcriptomic responses in both LL and HL Synechococcus sp.…”

Section: Transcriptome Response To Oxidative Stressmentioning

confidence: 91%

“…Accordingly, ftsH_1216, the ROS-induced direct ortholog of Synechocystis sp. PCC 6803 slr0228 gene (Li et al, 2004;Houot et al, 2007), encoding the FtsH2 protease involved in the clearance of damaged D1 proteins from inactivated PSII , belongs to the cluster of genes mainly activated in response to ROS in Synechococcus sp. WH7803 (cluster B; Fig.…”

Section: Transcriptome Response To Oxidative Stressmentioning

confidence: 99%

Light History Influences the Response of the Marine CyanobacteriumSynechococcussp. WH7803 to Oxidative Stress

et al. 2011

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Marine Synechococcus undergo a wide range of environmental stressors, especially high and variable irradiance, which may induce oxidative stress through the generation of reactive oxygen species (ROS). While light and ROS could act synergistically on the impairment of photosynthesis, inducing photodamage and inhibiting photosystem II repair, acclimation to high irradiance is also thought to confer resistance to other stressors. To identify the respective roles of light and ROS in the photoinhibition process and detect a possible light-driven tolerance to oxidative stress, we compared the photophysiological and transcriptomic responses of Synechococcus sp. WH7803 acclimated to low light (LL) or high light (HL) to oxidative stress, induced by hydrogen peroxide (H 2 O 2 ) or methylviologen. While photosynthetic activity was much more affected in HL than in LL cells, only HL cells were able to recover growth and photosynthesis after the addition of 25 mM H 2 O 2 . Depending upon light conditions and H 2 O 2 concentration, the latter oxidizing agent induced photosystem II inactivation through both direct damage to the reaction centers and inhibition of its repair cycle. Although the global transcriptome response appeared similar in LL and HL cells, some processes were specifically induced in HL cells that seemingly helped them withstand oxidative stress, including enhancement of photoprotection and ROS detoxification, repair of ROS-driven damage, and regulation of redox state. Detection of putative LexA binding sites allowed the identification of the putative LexA regulon, which was downregulated in HL compared with LL cells but up-regulated by oxidative stress under both growth irradiances.

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“…Aliquots of 200 ml of mid-log-phase cultures (2.5 ϫ 10 7 cells ml Ϫ1 ) were rapidly harvested by vacuum filtration (less than 1 min), resuspended in 4 ml of 50 mM Tris 50 (pH 8), 5 mM EDTA, immediately frozen in an Eaton press chamber cooled in a dry ice and ethanol bath, and disrupted (250 MPa). RNA was extracted and purified with the Qiagen RNeasy kit as we have previously described (18) and then treated with 20 U of DNase I, RNase-free (Applied Biosystems) for 30 min at 37°C. RNA concentration and purity (A 260 /A 280 ratio, Ͼ1.9) were determined with a Nanodrop apparatus (Thermo Scientific) and migration on an agarose gel to verify the absence of RNA degradation.…”

Section: Methodsmentioning

confidence: 99%

The AbrB2 Autorepressor, Expressed from an Atypical Promoter, Represses the Hydrogenase Operon To Regulate Hydrogen Production in Synechocystis Strain PCC6803

et al. 2012

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eWe have thoroughly investigated the abrB2 gene (sll0822) encoding an AbrB-like regulator in the wild-type strain of the model cyanobacterium Synechocystis strain PCC6803. We report that abrB2 is expressed from an active but atypical promoter that possesses an extended ؊10 element (TGTAATAT) that compensates for the absence of a ؊35 box. Strengthening the biological significance of these data, we found that the occurrence of an extended ؊10 promoter box and the absence of a ؊35 element are two well-conserved features in abrB2 genes from other cyanobacteria. We also show that AbrB2 is an autorepressor that is dispensable to cell growth under standard laboratory conditions. Furthermore, we demonstrate that AbrB2 also represses the hox operon, which encodes the Ni-Fe hydrogenase of biotechnological interest, and that the hox operon is weakly expressed even though it possesses the two sequences resembling canonical ؊10 and ؊35 promoter boxes. In both the AbrB2-repressed promoters of the abrB2 gene and the hox operon, we found a repeated DNA motif [TT-(N 5 )-AAC], which could be involved in AbrB2 repression. Supporting this hypothesis, we found that a TT-to-GG mutation of one of these elements increased the activity of the abrB2 promoter. We think that our abrB2-deleted mutant with increased expression of the hox operon and hydrogenase activity, together with the reporter plasmids we constructed to analyze the abrB2 gene and the hox operon, will serve as useful tools to decipher the function and the regulation of hydrogen production in Synechocystis. C yanobacteria are ancient photoautotrophic prokaryotes that are regarded as the progenitors of oxygenic photosynthesis (33, 39) and the plant chloroplast (8). Over time, cyanobacteria have evolved as the largest and most diverse groups of bacteria (44) and have colonized most waters and soils of our planet. The hardiness of cyanobacteria is due to their efficient photosynthesis, which uses nature's most abundant resources, solar energy, water, CO 2 , and mineral nutrients, to produce a large part of the atmospheric oxygen and organic assimilates for the food chain (52). On a global scale, cyanobacteria fix an estimated 25 gigatons of carbon from CO 2 per year into energy-dense biomass (37, 49). To perform this huge CO 2 fixation, cyanobacteria use 0.2 to 0.3% (49) of the total solar energy, 178,000 TW, reaching the Earth's surface (22). Thus, the amount of energy passing through cyanobacteria exceeds by more than 25 times the energy demand of human society (about 15 TW), roughly 1,000 times the total nuclear energy produced on Earth.

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Cadmium triggers an integrated reprogramming of the metabolism of Synechocystis PCC6803, under the control of the Slr1738 regulator

Cited by 84 publications

References 65 publications

Delayed fluorescence imaging of photosynthesis inhibitor and heavy metal induced stress in potato

Delayed fluorescence imaging of photosynthesis inhibitor and heavy metal induced stress in potato

Light History Influences the Response of the Marine CyanobacteriumSynechococcussp. WH7803 to Oxidative Stress

The AbrB2 Autorepressor, Expressed from an Atypical Promoter, Represses the Hydrogenase Operon To Regulate Hydrogen Production in Synechocystis Strain PCC6803

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