Extreme Halophiles Synthesize Betaine from Glycine by Methylation

Glycine betaine is a compatible solute, which is able to restore and maintain osmotic balance of living cells. It is synthesized and accumulated in response to abiotic stress. Betaine acts also as a methyl group donor and has a number of important applications including its use as a feed additive. T...

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Bibliographic Details
Published in:The Journal of biological chemistry 2000-07, Vol.275 (29), p.22196-22201
Main Authors: Nyyssölä, Antti, Kerovuo, Janne, Kaukinen, Pasi, von Weymarn, Niklas, Reinikainen, Tapani
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Betaine - chemistry
Betaine - metabolism
Glycine - chemistry
Glycine - metabolism
Halobacteriales - metabolism
Methylation
Molecular Sequence Data
Sequence Alignment
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Summary:Glycine betaine is a compatible solute, which is able to restore and maintain osmotic balance of living cells. It is synthesized and accumulated in response to abiotic stress. Betaine acts also as a methyl group donor and has a number of important applications including its use as a feed additive. The known biosynthetic pathways of betaine are universal and very well characterized. A number of enzymes catalyzing the two-step oxidation of choline to betaine have been isolated. In this work we have studied a novel betaine biosynthetic pathway in two phylogenically distant extreme halophiles,Actinopolyspora halophila and Ectothiorhodospira halochloris. We have identified a three-step series of methylation reactions from glycine to betaine, which is catalyzed by two methyltransferases, glycine sarcosine methyltransferase and sarcosine dimethylglycine methyltransferase, with partially overlapping substrate specificity. The methyltransferases from the two organisms show high sequence homology. E. halochlorismethyltransferase genes were successfully expressed inEscherichia coli, and betaine accumulation and improved salt tolerance were demonstrated.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M910111199