Rhizobium leguminosarum bv. viciae 3841 contains six putative quaternary ammonium transporters (Qat), of the ABC family. Qat6 was strongly induced by hyperosmosis although the solute transported was not identified. All six systems were induced by the quaternary amines choline and glycine betaine. It was confirmed by microarray analysis of the genome that pRL100079-83 (qat6) is the most strongly...

Glycine betaine is accumulated in cells living in high salt concentrations to balance the osmotic pressure. Glycine sarcosine N-methyltransferase (GSMT) and sarcosine dimethylglycine N-methyltransferase (SDMT) of Ectothiorhodospira halochloris catalyze the threefold methylation of glycine to betaine, with S-adenosylmethionine acting as the methyl group donor. These methyltransferases were expre...

Introduction Betaine (trimethylglycine), the trimethylated compound of the amino acid glycine, is an essential biochemical component of the methionine/homocysteine cycle. Betaine acts as a donor of methyl (CH 3 ) groups and, as such, is often used as a nutritional supplement to lower plasma homocysteine levels, and as a lipotropic; i.e., a substance that improves liver function. Betaine also he...

After having shown that ectoine (a tetrahydropyrimidine) displays osmoprotective properties towards Escherichia coli (M. Jebbar, R. Talibart, K. Gloux, T. Bernard, and Blanco, J. Bacteriol. 174:5027-5035, 1992), we have investigated the involvement of this molecule in the osmotic adaptation of Rhizobium meliloti. Ectoine appeared almost as effective as glycine betaine in improving the growth of...

The halophilic methanoarchaeon Methanohalophilus portucalensis FDF1T possesses the ability to synthesize the osmolyte betaine from its precursor, glycine, in response to extracellular salt stress through a three-step transmethylation process. Analysis of recombinant glycine sarcosine N-methyltransferase (rGSMT) and recombinant sarcosine dimethylglycine N-methyltransferase (rSDMT) from Escherich...

The presence of betaine, a quaternary ammonium compound, at a concentration (0.5 molar) reported to accumulate inside Aphanothece halophytica in response to increasing external salinity, slightly promoted ribulose-1,5-bisphosphate (RuBP) carboxylase activity. KCl at 0.25 molar inhibited RuBP carboxylase about 55%. Betaine relieved the inhibition by 0.25 m KCl and the original uninhibited activi...

Salinity stress restricts growth of soybean plant [Glycine max (L.) Merr.]. Glycine betaine (GB) is among osmoprotectant compounds that are produced in tolerant plant species in response to environmental stresses. Soybean is sensitive to soil salinity and is classified as a low-ccumulator of glycine betaine. Therefore, this study was performed to evaluate the salinity tolerance of two contrasti...

The plant pathogen Pseudomonas syringae may cope with osmotic stress on plants, in part, by importing osmoprotective compounds. In this study, we found that P. syringae pv. tomato strain DC3000 was distinct from most bacterial species in deriving greater osmoprotection from exogenous choline than from glycine betaine. This superior osmoprotection was correlated with a higher capacity for uptake...

The plant pathogen Pseudomonas syringae may cope with osmotic stress on plants, in part, by importing osmoprotective compounds. In this study, we found that P. syringae pv. tomato strain DC3000 was distinct from most bacterial species in deriving greater osmoprotection from exogenous choline than from glycine betaine. This superior osmoprotection was correlated with a higher capacity for uptake...