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Biosynthetic pathways of glycinebetaine in Thalassiosira pseudonana; functional characterization of enzyme catalyzing three-step methylation of glycine
- Source :
- Plant Physiology and Biochemistry. 127:248-255
- Publication Year :
- 2018
- Publisher :
- Elsevier BV, 2018.
-
Abstract
- Betaine (trimethylglycine) is an important compatible solute that accumulates in response to abiotic stresses such as drought and salinity. Biosynthetic pathways of betaine have been extensively studied, but it remains to be clarified on algae. A diatom Thalassiosira pseudonana CCMP1335 is an important component of marine ecosystems. Here we show that the genome sequence of Thalassiosira suggests the presence of two biosynthetic pathways for betaine, via three step methylation of glycine and via two step oxidation of choline. The choline oxidation via choline dehydrogenase was suggested and its sequential characteristics were analyzed. A candidate gene TpORF1 for glycine methylation encodes a protein consisted of 574 amino acids with two putative tandem repeat methyltransferase domains. The TpORF1 was expressed in E. coli, and the purified protein was shown to synthesize betaine via three step methylation of glycine and designated as TpGSDMT. The proteins containing C-terminal half or N-terminal half were expressed in E. coli and exhibited the methyl transferase activities with different substrate specificity for glycine, sarcosine and dimethylglycine. Upregulation of TpGSDMT transcription and betaine levels were observed at high salinity, suggesting the importance of TpGSDMT for salt tolerance in T. pseudonana cells.
- Subjects :
- 0301 basic medicine
Choline dehydrogenase
Sarcosine
Physiology
Thalassiosira pseudonana
Glycine
Plant Science
Methylation
Choline
Dimethylglycine
03 medical and health sciences
chemistry.chemical_compound
Betaine
Genetics
Diatoms
chemistry.chemical_classification
Genome
biology
High-Throughput Nucleotide Sequencing
Methyltransferases
biology.organism_classification
Amino acid
030104 developmental biology
chemistry
Biochemistry
Trimethylglycine
Subjects
Details
- ISSN :
- 09819428
- Volume :
- 127
- Database :
- OpenAIRE
- Journal :
- Plant Physiology and Biochemistry
- Accession number :
- edsair.doi.dedup.....2a23bfb2786c192609aa2ea83258320c