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Comparative analysis on the key enzymes of the glycerol cycle metabolic pathway in Dunaliella salina under osmotic stresses.

Chen H, Lu Y, Jiang JG - PLoS ONE (2012)

Bottom Line: The glycerol metabolic pathway is a special cycle way; glycerol-3-phosphate dehydrogenase (G3pdh), glycerol-3-phosphate phosphatase (G3pp), dihydroxyacetone reductase (Dhar), and dihydroxyacetone kinase (Dhak) are the key enzymes around the pathway.Dhar played a role of balancing the cycle metabolic pathway by its forward and backward reactions.Through synergy, the four enzymes worked together for the effective flow of the cycle metabolic pathways to maintain the glycerol requirements of cells in order to adapt to osmotic stress environments.

View Article: PubMed Central - PubMed

Affiliation: College of Food Bioengineering, South China University of Technology, Guangzhou, China.

ABSTRACT
The glycerol metabolic pathway is a special cycle way; glycerol-3-phosphate dehydrogenase (G3pdh), glycerol-3-phosphate phosphatase (G3pp), dihydroxyacetone reductase (Dhar), and dihydroxyacetone kinase (Dhak) are the key enzymes around the pathway. Glycerol is an important osmolyte for Dunaliella salina to resist osmotic stress. In this study, comparative activities of the four enzymes in D. salina and their activity changes under various salt stresses were investigated, from which glycerol metabolic flow direction in the glycerol metabolic pathway was estimated. Results showed that the salinity changes had different effects on the enzymes activities. NaCl could stimulate the activities of all the four enzymes in various degrees when D. salina was grown under continuous salt stress. When treated by hyperosmotic or hypoosmotic shock, only the activity of G3pdh in D. salina was significantly stimulated. It was speculated that, under osmotic stresses, the emergency response of the cycle pathway in D. salina was driven by G3pdh via its response to the osmotic stress. Subsequently, with the changes of salinity, other three enzymes started to respond to osmotic stress. Dhar played a role of balancing the cycle metabolic pathway by its forward and backward reactions. Through synergy, the four enzymes worked together for the effective flow of the cycle metabolic pathways to maintain the glycerol requirements of cells in order to adapt to osmotic stress environments.

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Dhak activity in D. salina cells under different salinity stresses.Columns represent the means of three replicated studies in each sample, with the SD of the means (T test, P<0.05). The significance of the differences between the control (2.0) and test values were tested by using one-way ANOVA. *, P<0.05 vs control.
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pone-0037578-g005: Dhak activity in D. salina cells under different salinity stresses.Columns represent the means of three replicated studies in each sample, with the SD of the means (T test, P<0.05). The significance of the differences between the control (2.0) and test values were tested by using one-way ANOVA. *, P<0.05 vs control.

Mentions: Dhak had nearly no activity changes under continuous cultivation from 0.5 to 3.0 M NaCl (<5 U/mg), but the activities increased significantly with further increased salinities and achieved the maximum (42.19±9.14 U/mg) under 4.5 M NaCl. Under 5.0 M NaCl, Dhak was also showed a high activity of 22.85±9.05 U/mg. However, when D. salina treated by hypoosmotic or hyperosmotic shock, there were no significant correlation between Dhak activities and salinities, and its activities in all treatments were similar to that of cells grown continuously under 0.5–3.0 M NaCl (Figure 5).


Comparative analysis on the key enzymes of the glycerol cycle metabolic pathway in Dunaliella salina under osmotic stresses.

Chen H, Lu Y, Jiang JG - PLoS ONE (2012)

Dhak activity in D. salina cells under different salinity stresses.Columns represent the means of three replicated studies in each sample, with the SD of the means (T test, P<0.05). The significance of the differences between the control (2.0) and test values were tested by using one-way ANOVA. *, P<0.05 vs control.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3366960&req=5

pone-0037578-g005: Dhak activity in D. salina cells under different salinity stresses.Columns represent the means of three replicated studies in each sample, with the SD of the means (T test, P<0.05). The significance of the differences between the control (2.0) and test values were tested by using one-way ANOVA. *, P<0.05 vs control.
Mentions: Dhak had nearly no activity changes under continuous cultivation from 0.5 to 3.0 M NaCl (<5 U/mg), but the activities increased significantly with further increased salinities and achieved the maximum (42.19±9.14 U/mg) under 4.5 M NaCl. Under 5.0 M NaCl, Dhak was also showed a high activity of 22.85±9.05 U/mg. However, when D. salina treated by hypoosmotic or hyperosmotic shock, there were no significant correlation between Dhak activities and salinities, and its activities in all treatments were similar to that of cells grown continuously under 0.5–3.0 M NaCl (Figure 5).

Bottom Line: The glycerol metabolic pathway is a special cycle way; glycerol-3-phosphate dehydrogenase (G3pdh), glycerol-3-phosphate phosphatase (G3pp), dihydroxyacetone reductase (Dhar), and dihydroxyacetone kinase (Dhak) are the key enzymes around the pathway.Dhar played a role of balancing the cycle metabolic pathway by its forward and backward reactions.Through synergy, the four enzymes worked together for the effective flow of the cycle metabolic pathways to maintain the glycerol requirements of cells in order to adapt to osmotic stress environments.

View Article: PubMed Central - PubMed

Affiliation: College of Food Bioengineering, South China University of Technology, Guangzhou, China.

ABSTRACT
The glycerol metabolic pathway is a special cycle way; glycerol-3-phosphate dehydrogenase (G3pdh), glycerol-3-phosphate phosphatase (G3pp), dihydroxyacetone reductase (Dhar), and dihydroxyacetone kinase (Dhak) are the key enzymes around the pathway. Glycerol is an important osmolyte for Dunaliella salina to resist osmotic stress. In this study, comparative activities of the four enzymes in D. salina and their activity changes under various salt stresses were investigated, from which glycerol metabolic flow direction in the glycerol metabolic pathway was estimated. Results showed that the salinity changes had different effects on the enzymes activities. NaCl could stimulate the activities of all the four enzymes in various degrees when D. salina was grown under continuous salt stress. When treated by hyperosmotic or hypoosmotic shock, only the activity of G3pdh in D. salina was significantly stimulated. It was speculated that, under osmotic stresses, the emergency response of the cycle pathway in D. salina was driven by G3pdh via its response to the osmotic stress. Subsequently, with the changes of salinity, other three enzymes started to respond to osmotic stress. Dhar played a role of balancing the cycle metabolic pathway by its forward and backward reactions. Through synergy, the four enzymes worked together for the effective flow of the cycle metabolic pathways to maintain the glycerol requirements of cells in order to adapt to osmotic stress environments.

Show MeSH
Related in: MedlinePlus