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Salt acclimation of cyanobacteria and their application in biotechnology.

Pade N, Hagemann M - Life (Basel) (2014)

Bottom Line: Cyanobacterial salt acclimation has been characterized in much detail using selected model cyanobacteria, but their salt sensing and regulatory mechanisms are less well understood.This knowledge is of increasing importance because the necessary mass cultivation of cyanobacteria for future use in biotechnology will be performed in sea water.In addition, cyanobacterial salt resistance genes also can be applied to improve the salt tolerance of salt sensitive organisms, such as crop plants.

View Article: PubMed Central - PubMed

Affiliation: Institut für Biowissenschaften, Abteilung Pflanzenphysiologie, Universität Rostock, Albert-Einstein-Str. 3, D-18059 Rostock, Germany. nadin.pade@uni-rostock.de.

ABSTRACT
The long evolutionary history and photo-autotrophic lifestyle of cyanobacteria has allowed them to colonize almost all photic habitats on Earth, including environments with high or fluctuating salinity. Their basal salt acclimation strategy includes two principal reactions, the active export of ions and the accumulation of compatible solutes. Cyanobacterial salt acclimation has been characterized in much detail using selected model cyanobacteria, but their salt sensing and regulatory mechanisms are less well understood. Here, we briefly review recent advances in the identification of salt acclimation processes and the essential genes/proteins involved in acclimation to high salt. This knowledge is of increasing importance because the necessary mass cultivation of cyanobacteria for future use in biotechnology will be performed in sea water. In addition, cyanobacterial salt resistance genes also can be applied to improve the salt tolerance of salt sensitive organisms, such as crop plants.

No MeSH data available.


Biochemical pathways for the synthesis of sucrose, trehalose (OtsAB pathway, used only by Crocosphaera watsonii in cyanobacteria), glucosylglycerol (GG) and glucosylglycerate (GGA).
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life-05-00025-f001: Biochemical pathways for the synthesis of sucrose, trehalose (OtsAB pathway, used only by Crocosphaera watsonii in cyanobacteria), glucosylglycerol (GG) and glucosylglycerate (GGA).

Mentions: As photoautotrophic organisms, cyanobacteria prefer the de novo synthesis of compatible solutes. The biosynthetic pathways and the genes coding for the corresponding enzymes are known for all principal compatible solutes in cyanobacteria [5]. Sucrose, GG and GGA are all synthesized by two-step pathways. In the first step, a sugar-phosphate synthase (e.g., GG-phosphate synthase (GGPS)) synthesizes a phosphorylated intermediate by condensing a sugar nucleotide (for sucrose, UDP-glucose is used; for GG and GGA, ADP-glucose is used) and the corresponding phosphorylated sugar molecule (e.g., fructose 6-phosphate, glycerol 3-phosphate, glycerate 3-phosphate). In the second step, the phosphorylated compatible solute is then hydrolyzed to the final product by a specific phosphatase (e.g., GG-phosphate phosphatase (GGPP)) (Figure 1) [26,41,42,43,44]. In enterobacteria and plants, trehalose synthesis also is performed by a two-step mechanism using the so-called OtsAB pathway [11], whereas cyanobacteria usually use the so-called TreY/TreZ pathway for trehalose synthesis. This pathway begins with glycogen as a precursor. In the first reaction the final sugar bond is changed from the α-1,4 to the α-1,1 configuration, and then the two final glucose moieties are cleaved off as trehalose from the high molecular weight precursor, as was first shown in the freshwater model strain Nostoc (Anabaena) sp. PCC 7120 [45]. Recently, the bacteria-like OtsAB pathway for trehalose synthesis was identified as restricted to the marine cyanobacterium Crocosphaera. This strain most likely received the gene via horizontal gene transfer from heterotrophic marine bacteria [29]. An additional trehalose synthesis pathway may exist in cyanobacteria because salt-induced trehalose accumulation was detected in Microcystis aeruginosa, however none of the genes for the two known trehalose synthesis pathways is present in its genome (Hagemann and Dittmann, unpublished observation). The cyanobacterial glycine betaine synthesis also differs from the mechanism used by the majority of organisms, which generate glycine betaine by the two-step oxidation of choline [11]. Cyanobacteria and some other phototrophic bacteria instead use glycine as precursor that is methylated in three subsequent reactions, which are performed by two different enzymes, as shown first in the halophilic model cyanobacterium Aphanothece halophytica [46].


Salt acclimation of cyanobacteria and their application in biotechnology.

Pade N, Hagemann M - Life (Basel) (2014)

Biochemical pathways for the synthesis of sucrose, trehalose (OtsAB pathway, used only by Crocosphaera watsonii in cyanobacteria), glucosylglycerol (GG) and glucosylglycerate (GGA).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390839&req=5

life-05-00025-f001: Biochemical pathways for the synthesis of sucrose, trehalose (OtsAB pathway, used only by Crocosphaera watsonii in cyanobacteria), glucosylglycerol (GG) and glucosylglycerate (GGA).
Mentions: As photoautotrophic organisms, cyanobacteria prefer the de novo synthesis of compatible solutes. The biosynthetic pathways and the genes coding for the corresponding enzymes are known for all principal compatible solutes in cyanobacteria [5]. Sucrose, GG and GGA are all synthesized by two-step pathways. In the first step, a sugar-phosphate synthase (e.g., GG-phosphate synthase (GGPS)) synthesizes a phosphorylated intermediate by condensing a sugar nucleotide (for sucrose, UDP-glucose is used; for GG and GGA, ADP-glucose is used) and the corresponding phosphorylated sugar molecule (e.g., fructose 6-phosphate, glycerol 3-phosphate, glycerate 3-phosphate). In the second step, the phosphorylated compatible solute is then hydrolyzed to the final product by a specific phosphatase (e.g., GG-phosphate phosphatase (GGPP)) (Figure 1) [26,41,42,43,44]. In enterobacteria and plants, trehalose synthesis also is performed by a two-step mechanism using the so-called OtsAB pathway [11], whereas cyanobacteria usually use the so-called TreY/TreZ pathway for trehalose synthesis. This pathway begins with glycogen as a precursor. In the first reaction the final sugar bond is changed from the α-1,4 to the α-1,1 configuration, and then the two final glucose moieties are cleaved off as trehalose from the high molecular weight precursor, as was first shown in the freshwater model strain Nostoc (Anabaena) sp. PCC 7120 [45]. Recently, the bacteria-like OtsAB pathway for trehalose synthesis was identified as restricted to the marine cyanobacterium Crocosphaera. This strain most likely received the gene via horizontal gene transfer from heterotrophic marine bacteria [29]. An additional trehalose synthesis pathway may exist in cyanobacteria because salt-induced trehalose accumulation was detected in Microcystis aeruginosa, however none of the genes for the two known trehalose synthesis pathways is present in its genome (Hagemann and Dittmann, unpublished observation). The cyanobacterial glycine betaine synthesis also differs from the mechanism used by the majority of organisms, which generate glycine betaine by the two-step oxidation of choline [11]. Cyanobacteria and some other phototrophic bacteria instead use glycine as precursor that is methylated in three subsequent reactions, which are performed by two different enzymes, as shown first in the halophilic model cyanobacterium Aphanothece halophytica [46].

Bottom Line: Cyanobacterial salt acclimation has been characterized in much detail using selected model cyanobacteria, but their salt sensing and regulatory mechanisms are less well understood.This knowledge is of increasing importance because the necessary mass cultivation of cyanobacteria for future use in biotechnology will be performed in sea water.In addition, cyanobacterial salt resistance genes also can be applied to improve the salt tolerance of salt sensitive organisms, such as crop plants.

View Article: PubMed Central - PubMed

Affiliation: Institut für Biowissenschaften, Abteilung Pflanzenphysiologie, Universität Rostock, Albert-Einstein-Str. 3, D-18059 Rostock, Germany. nadin.pade@uni-rostock.de.

ABSTRACT
The long evolutionary history and photo-autotrophic lifestyle of cyanobacteria has allowed them to colonize almost all photic habitats on Earth, including environments with high or fluctuating salinity. Their basal salt acclimation strategy includes two principal reactions, the active export of ions and the accumulation of compatible solutes. Cyanobacterial salt acclimation has been characterized in much detail using selected model cyanobacteria, but their salt sensing and regulatory mechanisms are less well understood. Here, we briefly review recent advances in the identification of salt acclimation processes and the essential genes/proteins involved in acclimation to high salt. This knowledge is of increasing importance because the necessary mass cultivation of cyanobacteria for future use in biotechnology will be performed in sea water. In addition, cyanobacterial salt resistance genes also can be applied to improve the salt tolerance of salt sensitive organisms, such as crop plants.

No MeSH data available.