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Mechanisms of High Temperature Resistance of Synechocystis sp. PCC 6803: An Impact of Histidine Kinase 34.

Červený J, Sinetova MA, Zavřel T, Los DA - Life (Basel) (2015)

Bottom Line: PCC 6803 is a widely used model cyanobacterium for studying responses and acclimation to different abiotic stresses.We have shown that the majority of wild type cell population was able to recover after 24 h of cultivation at 44 °C.In addition, it appears that histidine kinase Hik34 is an essential component for the long term high temperature resistance.

View Article: PubMed Central - PubMed

Affiliation: Department of Adaptation Biotechnologies, Global Change Research Centre, Academy of Sciences of the Czech Republic, Drásov 470, CZ-66424 Drásov, Czech Republic. cerveny.j@czechglobe.cz.

ABSTRACT
Synechocystis sp. PCC 6803 is a widely used model cyanobacterium for studying responses and acclimation to different abiotic stresses. Changes in transcriptome, proteome, lipidome, and photosynthesis in response to short term heat stress are well studied in this organism, and histidine kinase 34 (Hik34) is shown to play an important role in mediating such response. Corresponding data on long term responses, however, are fragmentary and vary depending on parameters of experiments and methods of data collection, and thus are hard to compare. In order to elucidate how the early stress responses help cells to sustain long-term heat stress, as well as the role of Hik34 in prolonged acclimation, we examined the resistance to long-term heat stress of wild-type and ΔHik34 mutant of Synechocystis. In this work, we were able to precisely control the long term experimental conditions by cultivating Synechocystis in automated photobioreactors, measuring selected physiological parameters within a time range of minutes. In addition, morphological and ultrastructural changes in cells were analyzed and western blotting of individual proteins was used to study the heat stress-affected protein expression. We have shown that the majority of wild type cell population was able to recover after 24 h of cultivation at 44 °C. In contrast, while ΔHik34 mutant cells were resistant to heat stress within its first hours, they could not recover after 24 h long high temperature treatment. We demonstrated that the early induction of HspA expression and maintenance of high amount of other HSPs throughout the heat incubation is critical for successful adaptation to long-term stress. In addition, it appears that histidine kinase Hik34 is an essential component for the long term high temperature resistance.

No MeSH data available.


Related in: MedlinePlus

Pigment content dynamics in WT (a, b) and ΔHik34 mutant (c, d) cells during heat stress and recovery. a, c—Absorption spectra normalized to zero at 750 nm. b, d—cellular chlorophyll a and carotenoid content. Dashed lines mark time of heat shock treatment. The results represent a typical data of 4 independent experiments for both WT and ΔHik34 mutant. Error bars in panels b and d indicate standard deviations from 3 technical repetitions.
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life-05-00676-f003: Pigment content dynamics in WT (a, b) and ΔHik34 mutant (c, d) cells during heat stress and recovery. a, c—Absorption spectra normalized to zero at 750 nm. b, d—cellular chlorophyll a and carotenoid content. Dashed lines mark time of heat shock treatment. The results represent a typical data of 4 independent experiments for both WT and ΔHik34 mutant. Error bars in panels b and d indicate standard deviations from 3 technical repetitions.

Mentions: Changes in pigment content are shown in Figure 3. In WT cells, absorption spectra measurements (Figure 3a) showed that the content of all pigments (chlorophyll a, phycobilins, carotenoids) did not change significantly at high temperature. Pigments were even accumulated, though slowly, within 16 h of heat-stress treatment. Direct measurements of cellular chlorophyll a and carotenoid concentrations also confirmed the pigment accumulation during first 16 h of heat stress, however their contents decreased (especially of chlorophyll) between 16 h and 24 h at 44 °C (Figure 3b). A decrease in chlorophyll/carotenoids ratio from 3.9 to 2.6 was observed between 6 h and 24 h of heat stress. Pigment content was restored during recovery at 32 °C (Figure 3a,b): cellular chlorophyll and carotenoid concentrations, as well as chlorophyll/carotenoids ratio, increased significantly in 16 h and returned back to the original (control) values in 39 h.


Mechanisms of High Temperature Resistance of Synechocystis sp. PCC 6803: An Impact of Histidine Kinase 34.

Červený J, Sinetova MA, Zavřel T, Los DA - Life (Basel) (2015)

Pigment content dynamics in WT (a, b) and ΔHik34 mutant (c, d) cells during heat stress and recovery. a, c—Absorption spectra normalized to zero at 750 nm. b, d—cellular chlorophyll a and carotenoid content. Dashed lines mark time of heat shock treatment. The results represent a typical data of 4 independent experiments for both WT and ΔHik34 mutant. Error bars in panels b and d indicate standard deviations from 3 technical repetitions.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390874&req=5

life-05-00676-f003: Pigment content dynamics in WT (a, b) and ΔHik34 mutant (c, d) cells during heat stress and recovery. a, c—Absorption spectra normalized to zero at 750 nm. b, d—cellular chlorophyll a and carotenoid content. Dashed lines mark time of heat shock treatment. The results represent a typical data of 4 independent experiments for both WT and ΔHik34 mutant. Error bars in panels b and d indicate standard deviations from 3 technical repetitions.
Mentions: Changes in pigment content are shown in Figure 3. In WT cells, absorption spectra measurements (Figure 3a) showed that the content of all pigments (chlorophyll a, phycobilins, carotenoids) did not change significantly at high temperature. Pigments were even accumulated, though slowly, within 16 h of heat-stress treatment. Direct measurements of cellular chlorophyll a and carotenoid concentrations also confirmed the pigment accumulation during first 16 h of heat stress, however their contents decreased (especially of chlorophyll) between 16 h and 24 h at 44 °C (Figure 3b). A decrease in chlorophyll/carotenoids ratio from 3.9 to 2.6 was observed between 6 h and 24 h of heat stress. Pigment content was restored during recovery at 32 °C (Figure 3a,b): cellular chlorophyll and carotenoid concentrations, as well as chlorophyll/carotenoids ratio, increased significantly in 16 h and returned back to the original (control) values in 39 h.

Bottom Line: PCC 6803 is a widely used model cyanobacterium for studying responses and acclimation to different abiotic stresses.We have shown that the majority of wild type cell population was able to recover after 24 h of cultivation at 44 °C.In addition, it appears that histidine kinase Hik34 is an essential component for the long term high temperature resistance.

View Article: PubMed Central - PubMed

Affiliation: Department of Adaptation Biotechnologies, Global Change Research Centre, Academy of Sciences of the Czech Republic, Drásov 470, CZ-66424 Drásov, Czech Republic. cerveny.j@czechglobe.cz.

ABSTRACT
Synechocystis sp. PCC 6803 is a widely used model cyanobacterium for studying responses and acclimation to different abiotic stresses. Changes in transcriptome, proteome, lipidome, and photosynthesis in response to short term heat stress are well studied in this organism, and histidine kinase 34 (Hik34) is shown to play an important role in mediating such response. Corresponding data on long term responses, however, are fragmentary and vary depending on parameters of experiments and methods of data collection, and thus are hard to compare. In order to elucidate how the early stress responses help cells to sustain long-term heat stress, as well as the role of Hik34 in prolonged acclimation, we examined the resistance to long-term heat stress of wild-type and ΔHik34 mutant of Synechocystis. In this work, we were able to precisely control the long term experimental conditions by cultivating Synechocystis in automated photobioreactors, measuring selected physiological parameters within a time range of minutes. In addition, morphological and ultrastructural changes in cells were analyzed and western blotting of individual proteins was used to study the heat stress-affected protein expression. We have shown that the majority of wild type cell population was able to recover after 24 h of cultivation at 44 °C. In contrast, while ΔHik34 mutant cells were resistant to heat stress within its first hours, they could not recover after 24 h long high temperature treatment. We demonstrated that the early induction of HspA expression and maintenance of high amount of other HSPs throughout the heat incubation is critical for successful adaptation to long-term stress. In addition, it appears that histidine kinase Hik34 is an essential component for the long term high temperature resistance.

No MeSH data available.


Related in: MedlinePlus