Osmoprotectant β‐alanine betaine synthesis in the Plumbaginaceae: S‐adenosyl‐ l‐methionine dependent N‐methylation of β‐alanine to its betaine is via N‐methyl and N,N‐dimethyl β‐alanines

Abstract

Alanine betaine is an osmoprotective compound accumu-donor. Leaf extracts from -alanine betaine accumulators -Armeria maritima, L. latifolium and L. ramosissimum -had lated by most members of the plant family Plumbaginaceae. Leaf and root tissues of Limonium latifolium known to accu-detectable NMT activities while none were found in L. perezii, mulate -alanine betaine readily convert supplied -alanine to a species that does not accumulate -alanine betaine. The -alanine betaine. To identify the intermediates and the en-NMT activities were further characterized from the leaves of zymes involved in -alanine betaine synthesis, radiotracer L. latifolium. The activities had a pH optimum of 8.0, were experiments using [ 14 C] formate were employed. These studies soluble and inhibited by S-adenosyl-L-homocysteine. Extractable activities were similar from plants grown under demonstrate that -alanine betaine is synthesized from -alanine via N-methyl and N,N-dimethyl -alanines. A rapid and control and salinity stress conditions. Radiolabeling with [ 14 C] L-aspartic acid indicated that, unlike in bacteria, decarboxyla-sensitive radiometric assay was developed to measure Ntion of L-aspartic acid is not the source of -alanine in the methyltransferase (NMT) activities by using [methyl-14 C] or Plumbaginaceae.

β-Alanine N-Methyltransferase of Limonium latifolium. cDNA Cloning and Functional Expression of a Novel N-Methyltransferase Implicated in the Synthesis of the Osmoprotectant β-Alanine Betaine

“…Our previous radiotracer and enzyme measurements showed that ␤-Ala betaine synthesis was specific to ␤-Ala betaine-accumulating members of the Plumbaginaceae (Hanson et al, 1991;Rathinasabapathi et al, 2000). Consistent with this, ␤-Ala NMTase mRNA expression was present in L. latifolium and absent in L. sinuatum (Fig.…”

“…Accordingly, ␤-Ala betaine was distributed among species of the Plumbaginaceae, adapted to a wide range of adverse stress environments including saline and hypoxic conditions (Hanson et al, 1994). Although ␤-Ala betaine accumulation has been intensely studied for its role in osmoprotection (Hanson et al, 1994;Rathinasabapathi et al, 2000Rathinasabapathi et al, , 2001, early work on this compound in marine algae also suggested it to have a cholesterol-reducing effect in animal feeding experiments (Abe and Kaneda, 1973 Article, publication date, and citation information can be found at www.plantphysiol.org/cgi …”

Simultaneous determination of β-alanine betaine and trimethylamine in bacterial culture and plant samples by capillary electrophoresis

“…Of these nitrogenous compounds, considerable amounts of both TMA and β-alanine betaine were quantitatively estimated using the developed method (Table 1). Similarly, the concentration of β-alanine betaine in many plants of the family Plumbaginaceae was found in the range of 1 to 147 μg/g DW, which was estimated by either TLC and autoradiography (Rathinasabapathi et al 2000) or 1 H NMR (Baysalfurtana et al 2013). Collectively, the above findings clearly demonstrated the suitability of the developed method for the simultaneous detection and quantification of these analytes in microbial culture and plant samples.…”

“…Although glycine betaine is extensively accumulated in many plants in response to various environmental stresses, various members of the highly stresstolerant plant family Plumbaginaceae accumulate β-alanine betaine instead of glycine betaine (Hanson et al 1994). β-Alanine betaine synthesis is not controlled by choline availability, because it is derived from β-alanine by threestep methylation (Rathinasabapathi et al 2000). Distinct from glycine betaine synthesis, β-alanine betaine synthesis does not require oxygen, and therefore, it was proposed to be suitable for osmoprotection under saline and hypoxic conditions (Hanson et al 1994;Rathinasabapathi et al 2000).…”

“…β-Alanine betaine synthesis is not controlled by choline availability, because it is derived from β-alanine by threestep methylation (Rathinasabapathi et al 2000). Distinct from glycine betaine synthesis, β-alanine betaine synthesis does not require oxygen, and therefore, it was proposed to be suitable for osmoprotection under saline and hypoxic conditions (Hanson et al 1994;Rathinasabapathi et al 2000). Consequently, β-Alanine betaine appears to be effective over a broader ecological spectrum than glycine betaine (Rhodes and Hanson 1993).…”